Upcoming Seminars

Week of February 27Week of March 6Week of March 13Week of March 20

Chemical Engineering

Life in Suspense: Particle dynamics in suspensions of swimming bacteria

Tuesday, February 28, 2017; 9:15-10:15 am
108 Henderson
Speaker: Alison Patteson from University of Pennsylvania

Cells and microorganisms move in diverse environments that range from pond and ocean water to biological fluids, such as mucus. These environments frequently contain passive particles, such as macromolecules, flexible polymers, or colloids, which can influence cell motility and function. Interactions between cells and particles underlie many aspects of medicine, biology, and engineering, including the spread of bacterial infections, the formation of biofilms, and the design of swimming micro-robots. I use particles (1-10 micron) and polymer molecules (<1 micron) to experimentally investigate particle-bacteria interactions in suspensions of swimming Escherichia coli. By varying the size of passive spherical particles, I find an anomalous diffusive regime in E. coli suspensions, in which larger particles diffuse faster than smaller particles. This feature arises due to an interplay between the particle’s Brownian diffusion and convection through bacterial interactions. When flexible polymers are added to the suspending fluid, the E. coli drastically change their swimming behavior: cells swim faster and tumble less often, drastically enhancing their translational diffusion. By varying polymer molecular weight, I find that fluid viscosity suppresses cell tumbling while fluid elasticity increases swimming speed. I demonstrate that E. coli produce elastic stresses in the fluid by visualizing fluorescently-labeled DNA polymers, which deform and stretch under the applied flows generated by a single E. coli. Together these results uncover new avenues of transport in active fluids, which can be used to control the spread of bacteria or the dispersion of particles in microbial environments. I discuss applications to particle sedimentation in bacterial suspensions and explore how crawling cells move through and interact with small tissue-like pores.

Hosted by: Lisa Petrine,  Chemical Engineering  (lap31@psu.edu)

Reaction Mechanisms and Structure Sensitivity for Materials Discovery from first-principles in Heterogeneous Catalysis

Thursday, March 2, 2017; 9:30 - 10:30 am
102 Chemistry
Speaker: Manos Mavrikakis from University of Wisconsin

Reaction Mechanisms and Structure Sensitivity for Materials Discovery from first-principles in Heterogeneous Catalysis

Hosted by: Lisa Haines,  Chemical Engineering  (lhaines@engr.psu.edu)

Civil and Environmental Engineering

“Traffic Estimation and Control in the Era of Mixed Human Piloted and Autonomous Vehicles”

Wednesday, March 1, 2017; 9:30 am - 10:30 am
125 Reber Building
Speaker: Daniel Work from University of Illinois at Urbana-Champaign

Abstract: This talk will explore some new directions in estimation and control when the traffic stream is composed of a mix of human piloted and autonomous vehicles. First, we investigate the problem of modeling and estimating traffic flows in this mixed setting. A connection between the generalized Aw Rascle Zhang (ARZ) model and two-class traffic motivates the choice to describe the flow via a system of conservation laws. With the system dynamics defined, the traffic state is estimated via a fully nonlinear particle filtering approach, and results are compared to estimates obtained from a particle filter applied to a classical scalar conservation law description of traffic. Numerical experiments indicate that when the penetration rate of automated vehicles in the traffic stream is highly variable, the ARZ based estimator offers improved accuracy. Next, we explore the problem of controlling the human piloted traffic with only a small number of autonomous vehicles. We modify the experimental setting of Sugiyama et al. (2008) to measure the influence of a carefully controlled autonomous vehicle on human piloted vehicles.  Even when the penetration rate of automated vehicles is as low as 5%, we show it is possible to reduce the presence of stop-and-go waves that can appear without the presence of a bottleneck. Our experiments imply that significant improvements in traffic fuel efficiency and safety may be achieved by means of very few mobile actuators in the traffic stream. Biography: Daniel Work is an assistant professor in the Department of Civil and Environmental Engineering, the Department of Electrical and Computer Engineering (courtesy), and the Coordinated Science Laboratory at the University of Illinois at Urbana-Champaign. Prof. Work earned his bachelor of science degree (2006) from the Ohio State University, and a master of science (2007) and Ph.D. (2010) from the University of California, Berkeley, each in civil engineering. Prior to joining the faculty at Illinois, Work was a research intern at Nokia Research Center, Palo Alto from 2008-2009, and a guest researcher at Microsoft Research Redmond in 2010. Prof. Work has research interests in transportation cyber physical systems, traffic modeling, and infrastructure data analytics. Prof. Work’s honors include participation in the National Academy of Engineering’s 2017 China US Frontiers of Engineering Symposium and the 2016 EU US Frontiers of Engineering Symposium, the UIUC CEE Excellence Faculty Fellow award (2016), the UIUC ASCE Outstanding Professor award (2015), and the NSF CAREER award (2014).

Hosted by: Serena Sidwell,  Engineering Dean's Office  (sps5072@engr.psu.edu)

Computer Science and Engineering

“Overcoming Fundamental Inefficiencies in the Representation of Data in Conventional Architectures”

Monday, February 27, 2017; 10 a.m.
222 IST Building
Speaker: Joshua San Miguel from University of Toronto

Society has become so dependent on computing power that any inefficiencies in the way that we process information can considerably impede productivity and quality of life. Three emerging trends pose challenges to the design of more efficient computer systems. First, energy constraints are becoming more strict amidst the rising interest in IoT and mobile computing. Yet traditional architectures waste a great deal of energy ensuring exactness for the naturally approximate applications that run on these systems (e.g., noisy sensor input, user-subjective output). Second, data sets are growing to enormous proportions due to the rapid gathering of information in modern devices. We can no longer rely on data being readily available in on-chip storage. Third, active chip area is diminishing at smaller technology nodes due to thermal and power density limitations in process technology scaling. We can no longer fully utilize all on-chip hardware resources simultaneously. In this talk, I present new architectural techniques that tackle these challenges by recognizing that they stem from fundamental gaps in the way that data is contextualized in hardware. The goal of a processor is to process real-world information; yet in modern architectures, hardware perceives data as nothing more than bits. First, I show that awareness of the type of information encoded in the bits enables approximation of data values for greater efficiency under strict energy constraints. Second, I show that awareness of the location of information enables more concise caching of massive data sets. Third, I show that awareness of the significance of information enables better scheduling of computations based on their impact to the quality of the final result, improving utilization of precious on-chip resources. These ideas aim to mitigate fundamental inefficiencies in the data movement, storage and compute of today's systems.

Hosted by: Sharon Elder,  Electrical Engineering  (sle9@psu.edu)

Electrical Engineering

“Living with Idiots: What scientists must know to co-exist with non-scientists.”

Thursday, March 2, 2017; 4:35 p.m.
062 Willard
Speaker: John W. Hanold, Office of Sponsored Programs from Penn State

Abstract: “Fortunately or unfortunately, scientists do not control all the levers of power. Government officials answer to many constituencies, many of whom are not informed by scientific data or motivated by scientific interests. Two recent examples illustrate how scientists can run afoul of political realities. Dr. J. Reece Roth, Professor Emeritus at the University of Tennessee and author of Industrial Plasma Engineering, was sentenced to 48 months in prison for his involvement of Chinese and Iranian nationals on an Air Force funded research project. Dr. Michael Mann, Professor of Meteorology at Penn State and a leading global warming scientist, is the target of ongoing investigations by the Attorney General of the Commonwealth of Virginia. (Dr. Mann is a former faculty member of the University of Virginia.) Each of these cases highlight challenges facing scientists and engineers today. Specifically, we will review how government contracting officers impose publication restrictions, foreign national restrictions, and other export control requirements on academic research. We also will review how scientists should react to government oversight (whether it be politically motivated or otherwise). We may not welcome such interference in our academic affairs, but we cannot afford to ignore these realities.”

Hosted by: Vishal Monga,  Electrical Engineering  (vmonga@engr.psu.edu)

Engineering Dean's Office

“Integrated Science of Nanocarbon Materials: Towards Physics Enabled Meta-optics and BioEng Applications”

Tuesday, February 28, 2017; 2:00 - 3:00 p.m.
125 Reber Building
Speaker: Slava V. Rotkin from Lehigh University

Abstract: Many applications of nanotechnology were enabled by novel physics phenomena demonstrated in new materials. Among those, discovery of nanocarbon materials that include 0-dimensional fullerene spheres, 1d cylindrical nanotubes and 2d graphene sheets, stands out due to their unique mechanical, electronic, optical and thermal properties, each of which could be a subject of a separate talk. We will focus on a few applications that already matured, such as carbon electronics, and some that are just rising but have already showed a great potential. In each case, the returns will be shown to rely on using an integrated multi-faceted approach, crossing the boundaries of traditional disciplines. Recently nanotube-based field-effect transistors, integrated circuits and even a tiny “computer” have been demonstrated. Potential industrial nanotube fab would require a high-throughput nondestructive characterization technique, not available yet. The talk will explain how a microwave microscopy which uses the electro¬magnetic field with the wavelength 100,000,000 times larger than the tube diameter can not only perform imaging of individual tubes but also be used for metrology of their quantum properties. Second example will deal with the 2d materials and their surface optical modes: amazingly thin layers – just one atom thick – can efficiently carry photonics signals. Engineering of such modes is possible in 2d heterostructures, and matching 2d layered materials with metamaterials could give this study a new spin. Large success in separation and purification of nanotubes functionalized with ssDNA has allowed widespread use of these complexes in biomedical studies. Although still in its childhood, the biosensing and bioimaging with nanocarbon materials already shows first exciting results. Finally an outlook of future research in nanocarbons and related materials will be given. Biography: Slava V. Rotkin is Professor of Physics, and Professor of Materials Science & Engineering at Lehigh University, Bethlehem, PA. He received his M.Sc. (Summa Cum Laude) in Optoelectronics in 1994 from the Electrical Engineering University and his Ph.D. in Physics & Mathematics in 1997 from Ioffe Institute (both in St. Petersburg, Russia). Prof. Rotkin is a recipient of several scientific awards, including: Class of '68 Fellowship (2009), Libsch Early Career Research Award (2007), Feigl Junior Faculty Scholar (2004), Beckman Fellowship (2000), Royal Swedish Academy of Sciences Fellowship (1995), as well as Hillman Award for Excellence in Undergraduate Student Advising (2012). He is the Chair of the Nanocarbons Division at the ECS, IEEE Senior Member, and Member of the Editorial Board at Physics Research International.

Hosted by: Serena Sidwell,  Engineering Dean's Office  (sps5072@engr.psu.edu)

Engineering Science and Mechanics

Multiphase Flows: Thermomechanical Theory, Algorithms, and Simulations

Monday, February 27, 2017; 11:45am - 1:15pm
216 EES Building
Speaker: Ju Liu from Stanford University

Multiphase ?ow is a familiar phenomenon from daily life and occupies an important role in phys¬ics, engineering, and medicine. However, due to its disparity of spatiotemporal scales and elusive nature of many sub-processes, a complete theory of multiphase ?ows is still lacking. Phase-?eld models are con¬sidered well-suited for describing interfacial physics. The current study on phase-?eld modeling in ?uid mechanics mainly focuses on bubble dynamics and free surface problems. The full capability of phase-?eld models has not been fully realized by the multiphase ?ow com-munity. In this work, we ?rst sys¬tematically derive a new modeling framework for multiphase and mul¬ticomponent ?ows, using the celebrated microforce theory developed by Gurtin in solid phase transitions [2]. This modeling frame-work guarantees entropy production intrinsically. We will show that the thermomechanical theory de¬rived by Dunn and Serrin [1] is a special case in this framework by choosing an appropriate thermody¬namic potential. In addition to the modeling, novel numerical technologies are developed for the aforementioned theory [3]. The spatial discreti¬zation is designed based on the notion of functional en¬tropy variables; the temporal scheme is constructed based on a family of new quadrature rules. The re¬sulting fully discrete scheme is prov¬ably entropy dissipative and second-order accurate in time. A gen¬eral-purpose parallel isogeomet¬ric analysis code, PERIGEE, is developed to provide an ef?cient im-plementation platform. The boiling problem, which is a typical buoyancy-driven ?ow, is numerically investigated by making proper assumptions on transport parameters and boundary conditions. Com¬pared with traditional multiphase solvers, the dependency on empirical data is signi?cantly reduced for boiling simula¬tions. It will be demonstrated that this modeling approach provides a uni?ed predictive tool for both nucleate and ?lm boiling. The numerical results indicate the promising potential of the pro¬posed methodology for a wide range of multiphase ?ow problems.

Hosted by: Diane Bierly,  Engineering Science and Mechanics  (dbierly@engr.psu.edu)

Electrofluidics And Optofluidics: Bringing Moore's Law To Biomedical In Vitro Diagnostics And Life Sciences

Wednesday, March 1, 2017; 3:35pm - 4:25pm
160 Willard Building
Speaker: Weihan Guan from Department of Electrical Engineering, Penn State University

Whereas the complex computation problems have been efficiently tackled by the exponentially growing number of transistors integrated into a single chip, solving the incredible biomedical problems (especially at the molecular level) still faces many challenges. As the driving forces for Moore’s law in microelectronics, micro- and nano-scale technologies also hold great promise for unraveling the mystery in life sciences and developing the next generation of high throughput, easy-to-use, and reliable biomedical diagnostic devices and systems. In this talk, I will discuss how microfluidic, microelectronic and optic technologies can be mingled together (electrofluidics and optofluidics) to develop lab-on-a-chip devices for highly sensitive, specific and reliable biosensing applications. Specifically, I will present three representative examples: (1) silicon-bio interfaces (electrofluidics), (2) ‘sample-in-answer-out’ point-of-care molecular diagnosis (electro-opto-fluidics), and (3) digital microfluidics for single molecule detection (opto-fluidics). Micro/nanotechnology-enabled devices and systems serve as a fascinating starting point to increase the bio-analytical power in an exponential fashion and to bring the Moore's law into biomedical diagnostics and life sciences. My vision is that the landscape for life science industry and biomedical in-vitro diagnostics is set to be transformed by continuing fundamental and translational electrofluidic and optofluidics research.

Hosted by: Akhlesh Lakhtakia,  Engineering Science and Mechanics  (mff3@psu.edu)

Mechanical Engineering

Mechanoregulation of Collective Cell Migration

Monday, February 27, 2017; 4:00 - 5:00 PM
26 Hosler Building
Speaker: Pak Kin Wong from The Pennsylvania State University

Collective cell migration is a fundamental multicellular activity that plays essential roles in numerous physiological and pathological processes, such as tissue development, regeneration, and cancer metastasis.  Proper coordination of cells, for instance, is required to repair damaged tissues in which cells crawl collectively atop exposed extracellular matrix following injury.  The collective migration mechanisms responsible for tissue development are also utilized in the invasion and metastasis of malignant tumors.  Despite its significance, the fundamental processes that drive collective cell migration, such as leader cell formation and multicellular cooperativity, remain poorly understood.  To elucidate the molecular and cellular mechanisms governing collective cell migration, my laboratory is developing a single molecule biosensor for dynamic multigene analysis in complex tissue environments.  By integrating the single molecule biosensor with microengineered 3D tissue models, single cell photothermal ablation, biomechanical analysis, and agent-based computational modeling, we establish a mechanoregulation framework for probing collective cell migration.  Using the framework, we reveal that the formation of leader cells during collective migration is dynamically regulated by Dll4 signaling through both Notch1 and intercellular tension.  Our finding provides a molecular basis for the stochastic emergence of leader cells, which may enable novel approaches in regenerative medicine, wound healing and anti-metastasis therapy in the future.

Hosted by: Mary Frecker/M. Newby,  Mechanical Engineering  (mln7@psu.edu/3-6272)

Nuclear Engineering

Plutonium in the Environment: Can we Predict its Subsurface Behavior?

Thursday, March 2, 2017; 4:00 - 5:00 PM
22 Deike Building
Speaker: Annie B. Kersting from Lawrence Livermore National Laboratory

There is an acute need to expedite progress toward a permanent storage facility that can safely isolate long-lived actinides and fission products from the biosphere. Significant uncertainty remains on how to safely store long-lived radionuclides that will make up the majority of the dose after a few hundred years. Plutonium (Pu) is of particular interest because of its high toxicity and long half-life (t1/2 239Pu 2.4 x104 yrs). The chemical interactions of Pu are dependent on its oxidation state, which in turn control its stability and solubility. Understanding the interplay (the bio-geo-chemistry) between Pu and the repository environment is necessary to predict the conditions for which Pu will either migrate or remain immobile. A mechanistic understanding of the surface structure and reactivity of coupled Pu–mineral, Pu–organic ligand, and Pu–microbe, interfacial processes is needed to advance our understanding. To elucidate the mechanisms controlling Pu transport, we have investigated Pu sorption and desorption rates from mineral, organic and microbe surfaces over a range of concentrations found in the environment.  Field and laboratory experiments show that the both inorganic and organic matter play an important role in stabilizing Pu in solution and on mineral surfaces.  I will present an overview of our present understanding of the behaviour of Pu in an effort to develop a conceptual model of Pu subsurface behavior.

Hosted by: Dr. Kenan Unlu,  Mechanical Engineering  (mln7@psu.edu/3-6272)

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