Dr. Morgana Trexler of the Johns Hopkins Applied Physics Lab Joins HEMI

Please join us in welcoming the newest HEMI Fellow, Morgana Trexler! Dr. Trexler is a Materials Engineer with the Johns Hopkins Applied Physics Laboratory whose interests include high rate impact mechanics, armor, biomechanics, multifunctional and expeditionary materials. She received her doctorate in Materials Science and Engineering at the Georgia Institute of Technology. In 2014, she won the Outstanding Young Engineer award from the Maryland Academy of Sciences.

Welcome to HEMI, Dr. Trexler!


HEMI PhD Candidate Suhas Prameela Accepts MEDE-MSA Fellowship

Congratulations to Suhas Eswarappa Prameela on receiving the MEDE-MSA Research Fellowship! This fellowship enables current graduate students or postdocs working within the MEDE program the opportunity to participate in research activities at a MSA-affiliated university in the United Kingdom. With this fellowship, Prameela plans to explore the microstructure evolution of binary Magnesium alloys during thermo-mechanical processing. Prameela is a PhD candidate working in the Metals CMRG with Prof. Timothy Weihs. During the fellowship period, Prameela will work with Prof. Joseph Robson in the Department of Materials Engineering at the University of Manchester.

The MEDE-MSA fellowship is only open to graduate students or postdocs funded on MEDE whose principal faculty advisor is a current MEDE principal investigator (PI). The fellowship provides $6,000 (US) to support travel, housing and incidental costs. It is expected that the fellowship will be approximately eight weeks in duration which can be conducted throughout the year.

HEMI Fellow Muyinatu Bell to Receive Maryland Outstanding Young Engineer Award

HEMI Fellow Muyinatu Bell, an assistant professor in the Department of Electrical and Computer Engineering and the Department of Biomedical Engineering, has been chosen by the Maryland Academy of Sciences to receive the Maryland Outstanding Young Engineer Award.

Conferred by the Maryland Science Center, this award recognizes and encourages the important work being done by Maryland’s young professional engineers.
 As director of the Photoacoustic and Ultrasonic Systems Engineering (PULSE) Laboratory, Bell and her team integrate optics, acoustics, robotics, electronics, and mechanics, as well as signal processing and medical device design, to engineer and deploy innovative biomedical imaging systems that not only address unmet clinical needs, but also significantly improve patient care.

Congratulations, Prof. Bell!

2019 Mach Conference Showcases Fundamental Research for Materials and Structures in Extreme Environments

The 2019 Mach Conference, held last week in Annapolis, MD, brought together representatives from academia, government and industry to share their work in the field of materials, with an emphasis on advancing the fundamental science and engineering of materials and structures in extreme environments.. The conference’s plenary speakers included Dr. Benji Maruyama (Air Force Research Laboratory), Dr. Jonathan Almer (Argonne National Laboratory), Prof. Gilbert “Rip” Collins (University of Rochester), Prof. William A. Curtin (EPFL), and Dr. Dennis Dimiduk (BlueQuartz Software, LLC and The Ohio State University.)  Conference-goers attended lectures, presented on research, and socialized with their peers in the discipline.

Next year’s conference will be held on April 1-3, 2020. For more information, visit www.machconference.org.

HEMI Fellow Prof. Sung Hoon Kang Receives WSE Research Award for Lab Excellence

Congratulations to HEMI Fellow Prof. Sung Hoon Kang, for receiving the Whiting School of Engineering Research Award for Lab Excellence at the 2019 Department of Medicine/Whiting School of Engineering Research Retreat, held Friday, March 1, 2019 at Turner Auditorium.

Kang, an assistant professor in the Department of Mechanical Engineering, was invited to present on his lab’s research, which is focused on developing next-generation materials and mechanical systems inspired by nature. During his presentation, Kang discussed his group’s NIH-funded project to formulate a new soft material to use in 3D printed, self-adaptable cardiovascular devices for infants with congenital heart defects. The team hopes to harness the physiological changes that occur during growth to create an implant that can adapt and grow with the child. The larger goal is to reduce the number of open heart surgeries and complications for these young patients.

Award submissions were judged by a committee on the overall significance of the research and potential extension to broad themes of Engineering-Medicine collaborations.


HEMI Fellow Susanna Thon Receives NSF Career Award

Congratulations to HEMI Fellow Susanna Thon, who has been chosen by the National Science Foundation for its prestigious CAREER Award, which recognizes early-stage scholars with high levels of promise and excellence. Thon is an assistant professor in the Department of Electrical and Computer Engineering. Prof. Thon’s research is in the field of nanomaterials engineering for optoelectronic devices, with a specific focus on renewable energy conversion and storage. Her work applies techniques from nanophotonics and scalable fabrication to produce devices and materials with novel optical and electrical functionality.

Her CAREER project, “Finite-Absorption-Bandwidth Nanomaterials for Multijunction Photovoltaics and Narrow-Band Photodetectors,” has the potential to lead to a more efficient, usable, and cost-effective way of generating solar energy.

“The basic thrust of the project is, we came up with a new way to control the color of materials,” Thon said. “We drill periodic arrays of air holes into the absorbing materials called ‘photonic crystals’, and that changes how the materials absorb light. This is a way to perform ‘color tuning,’ so it is essentially a new strategy for controlling the color in these materials.”

Thon believes that these solar cells and light sensors could eventually help create a more efficient, usable, and cost-effective way of generating solar energy. She envisions a day when the cells and sensors could be made into paints that could be used on the exteriors of homes and other buildings to capture the sun’s energy, providing heating and cooling and powering appliances inside.

She predicts that much of the work on this project will focus on achieving the level of color tuning control needed to obtain optimal results—a challenge that she feels certain that she and her excellent team at Johns Hopkins can meet.

Congratulations, Prof. Thon!

Prof. Shoji Hall from the Department of Materials Science and Engineering Joins HEMI

Please join us in welcoming the newest HEMI Fellow, Prof. Shoji Hall! Prof. Hall is an assistant professor in the Department of Materials Science and Engineering. He studies chemical reactions catalyzed by solid surfaces to address problems in renewable energy storage and utilization. Dr. Anthony Shoji Hall joined the Whiting School of Engineering at Johns Hopkins University as an assistant professor in the Department of Materials Science and Engineering on July 1, 2016. Hall received his BS in chemistry from UCLA in 2010 and his PhD in chemistry from Penn State in 2014. Prior to joining Johns Hopkins, he was a postdoctoral research fellow at MIT in the Department of Chemistry. Welcome to HEMI, Prof. Hall!

Breaking Up is Hard to Do: Asteroids Are Stronger, Harder to Destroy Than Previously Thought

A frame-by-frame showing how gravity causes asteroid fragments to reaccumulate in the hours following impact.

A frame-by-frame showing how gravity causes asteroid fragments to reaccumulate in the hours following impact. (Credit: Charles El Mir / Johns Hopkins University)

A popular theme in the movies is that of an incoming asteroid that could extinguish life on the planet, and our heroes are launched into space to blow it up. But incoming asteroids may be harder to break than scientists previously thought, finds a Johns Hopkins study that used a new understanding of rock fracture and a new computer modeling method to simulate asteroid collisions.

The findings, to be published in the March 15 print issue of Icarus, can aid in the creation of asteroid impact and deflection strategies, increase understanding of solar system formation, and help design asteroid mining efforts.

“We used to believe that the larger the object, the more easily it would break, because bigger objects are more likely to have flaws. Our findings, however, show that asteroids are stronger than we used to think and require more energy to be completely shattered,” says Charles El Mir, a recent PhD graduate from the Johns Hopkins University’s Department of Mechanical Engineering and the paper’s first author.

Researchers understand physical materials like rocks at a laboratory scale (about the size of your fist), but it has been difficult to translate this understanding to city-size objects like asteroids. In the early 2000s, a different research team created a computer model into which they input various factors such as mass, temperature, and material brittleness, and simulated an asteroid about a kilometer in diameter striking head-on into a 25-kilometer diameter target asteroid at an impact velocity of five kilometers per second. Their results suggested that the target asteroid would be completely destroyed by the impact.

In the new study, El Mir and his colleagues, K.T. Ramesh, director of the Hopkins Extreme Materials Institute and Derek Richardson, professor of astronomy at the University of Maryland, entered the same scenario into a new computer model called the Tonge-Ramesh model, which accounts for the more detailed, smaller-scale processes that occur during an asteroid collision. Previous models did not properly account for the limited speed of cracks in the asteroids.

“Our question was, how much energy does it take to actually destroy an asteroid and break it into pieces?” says El Mir.

The simulation was separated into two phases: a short-timescale fragmentation phase and a long-timescale gravitational reaccumulation phase. The first phase considered the processes that begin immediately after an asteroid is hit, processes that occur within fractions of a second. The second, long-timescale phase considers the effect of gravity on the pieces that fly off the asteroid’s surface after the impact, with gravitational reaccumulation occurring over many hours after impact.

In the first phase, after the asteroid was hit, millions of cracks formed and rippled throughout the asteroid, parts of the asteroid flowed like sand, and a crater was created. This phase of the model examined the individual cracks and predicted overall patterns of how those cracks propagate. The new model showed that the entire asteroid is not broken by the impact, unlike what was previously thought. Instead, the impacted asteroid had a large damaged core that then exerted a strong gravitational pull on the fragments in the second phase of the simulation.


The research team found that the end result of the impact was not just a “rubble pile” – a collection of weak fragments loosely held together by gravity. Instead, the impacted asteroid retained significant strength because it had not cracked completely, indicating that more energy would be needed to destroy asteroids. Meanwhile, the damaged fragments were now redistributed over the large core, providing guidance to those who might want to mine asteroids during future space ventures.

“It may sound like science fiction but a great deal of research considers asteroid collisions. For example, if there’s an asteroid coming at earth, are we better off breaking it into small pieces, or nudging it to go a different direction? And if the latter, how much force should we hit it with to move it away without causing it to break? These are actual questions under consideration,” adds El Mir.

“We are impacted fairly often by small asteroids, such as in the Chelyabinsk event a few years ago,” says Ramesh. “It is only a matter of time before these questions go from being academic to defining our response to a major threat. We need to have a good idea of what we should do when that time comes – and scientific efforts like this one are critical to help us make those decisions.”

HEMI Fellow Muyinatu Bell Named Alfred P. Sloan Research Fellow

HEMI Fellow Muyinatu ‘Bisi’ Bell has been selected as a 2019 Alfred P. Sloan Research Fellow in Physics. Professor Bell is an assistant professor in the Department of Electrical and Computer Engineering and the Department of Biomedical Engineering. Prof. Bell leads a highly interdisciplinary research program that integrates optics, acoustics, robotics, and electronics to engineer and deploy innovative biomedical imaging systems that address unmet clinical needs. She is the director of the Photoacoustic and Ultrasonic Systems Engineering (PULSE) Lab, and the technologies developed in her lab have applications in neurosurgical navigation, cardiovascular disease, women’s health, and cancer detection and treatment. Dr. Bell is additionally interested in utilizing these novel technologies to investigate fundamental science questions surrounding the limits of laser-tissue interactions and their effect on tissue mechanical properties derived from acoustic measurements.

The Alfred P. Sloan Research Fellowship is awarded annually to young researchers based on their potential to make substantial contributions to their fields and their distinguished performance.

Congratulations to Prof. Bell on her achievement!