Department of Chemistry

A Career Worth Celebrating: Dr. Challa V. Kumar

Colleagues, collaborators, family, friends, and former students gathered to celebrate the career of Dr. Challa V. Kumar
Colleagues, collaborators, family, friends, and former students gathered to celebrate the career of Dr. Challa V. Kumar

By the time registration closed for the Symposium Celebrating the Research and Education Legacy of Professor Challa V. Kumar, more than 60 delegates from around the world had registered.  The event, which also celebrated Dr. Kumar’s retirement as well as his 70th birthday, brought together colleagues, collaborators, friends, and former students of Professor Kumar eager to pay homage to him and to present research on the topic for the day, Chemical Approaches to Biological Materials and Beyond.

The full-day event opened on September 9, 2023, with continental breakfast and a welcome message from Dr. Yao Lin, professor of chemistry and Institute of Materials Science (IMS) resident faculty member. Lin also served as chair for the morning session.  IMS Director Dr. Steven L. Suib opened the symposium with remarks that set the tone for the day’s events.

The morning session commenced with Dr. Kumar’s introduction of his longtime friend, Professor and Chief Editor of Science magazine, Holden Thorp. Dr. Thorp emphasized the importance of scientists getting involved in the discussion of societal issues and policies through evidence-based facts. The discussion included science outreach to children, an important topic for all attendees.

Each presentation was preceded by a short introduction from Dr. Kumar, to which he brought a personal connection between himself and each of the presenters. Speakers for the morning session included Professor D. Ramaiah from Birla Institute of Technology, Hyderabad, India. Dr. Kumar and Dr. Ramaiah overlapped at the Indian Institute of Technology Kanpur before Dr. Kumar left for the United States.

Morning session speakers
Morning session presenters (l to r) Drs. Yao Lin (session chair); Dr. D. Ramaiah, Michael Purugganan, Leah Croucher, and J.K. Barton

Professor Michael Purugganan from New York University described his collaboration with Professor Kumar on DNA-mediated electron transfer at Columbia University. He presented research on the ways in which rice genes have co-evolved with humans over thousands of years, with 13,000 varieties identified so far.

Professor Leah Croucher from the National Institutes of Health (NIH), a former Ph.D. student of Professor Kumar, described her path from the Kumar lab to NIH in reverse chronological order, sharing highlights of her days at UConn along the way.

The last speaker of the morning session was Professor J.K. Barton of California Institute of Technology. Dr. Barton, a recipient of the prestigious Priestly Medal, spoke on electron transfer through DNA. Dr. Barton was also a postdoctoral mentor to Professor Kumar. Her talk led to interesting discussions on the electron transport mechanism and how DNA-mediated electron transport plays an important role in DNA damage, repair, and cancer.

Afternoon session symposium speakers
Afternoon Session Speakers (l to r) Drs. Steven L. Suib, James Rusling, Ashis Basu, Rajeswari Kasi, Akhilesh Bhambhani, Ajith Pattammattel, and Anna Pyle

Following lunch, session chair Dr. Rajeswari Kasi, professor of chemistry and IMS resident faculty member, commenced the afternoon session with an introduction of IMS Director and Professor of Chemistry Dr. Steven L. Suib. Professor Suib analyzed the research trajectory of Dr. Kumar over four decades and recounted how the Kumar research group switched gears and meandered through increasingly interesting research topics, building one over the other.

Professor of Chemistry James Rusling spoke about his interactions with Professor Kumar, elaborating on joint and related projects that they often chatted about. Professor of Chemistry Ashis Basu described his research projects on DNA damage, DNA-covalent adducts of carcinogens, and the mechanisms of carcinogenesis. Professor Kasi described some of her most recent work on protein-conjugated cellulose nanocrystals, demonstrating how her work was inspired by her collaborations with Dr. Kumar.  Professor Akhilesh Bhambhani, a former Ph.D. student of Dr. Kumar, outlined the key factors for successful design, manufacturing, and deployment of biologics with humorous comparison of Dr. Kumar to the Bodha tree, which gave enlightenment to those who rested beneath it. Dr. Ajith Pattammattel, another former Ph.D. student of Dr. Kumar, elaborated on his research at the Brookhaven National Laboratory. He invited students and faculty to visit the lab to conduct collaborative advanced scattering experiments with a personal story of the instrumental role Dr. Kumar played in his success.

The penultimate talk of the symposium was given by Professor Anna Pyle, a contemporary of Dr. Kumar during her days as a graduate student at Columbia

University. Dr. Pyle described how her group is deciphering the exquisite structures of multiple states of RNA using Cryoelectron microscopy.

Dr. Challa Kumar was surrounded by family for the event. (l to r) Dr. Kumar’s wife Anupam, Dr. Kumar, his brother Srinivas, sister-in-law Manjula, nephew Sriram, and his wife Keerti

With the last word, Professor Kumar began his plenary talk by thanking his mentors, hosts, and graduate students. He elaborated on the tortuous path taken by his research group, and lessons learned, along the same lines as Professor Suib’s analysis at the beginning of the afternoon session.

The symposium concluded with a standing ovation from the audience, after Dr. Kumar explained how he came to the United States with only $21 and a Ph.D., with no friends or relatives here, and succeeded in achieving his American dream.  Truly a career worth celebrating!

Watch video of the symposium here.

IMS Faculty Members Working to Solve the Nation’s Energy Problems

from UConn Today

Yang Cao
Dr. Yang Cao

Three new grants totaling $7.5 million from ARPA-E and the U.S. Department of Energy (DOE) are enabling UConn researchers to conduct ground-breaking work on some of the nation’s most pressing energy problems. 

Advanced Research Projects Agency-Energy (ARPA-E) grants provide funding for the development of transformational technologies that provide new ways of generating, storing, and using energy.  

Shrinking Substations for Green Energy Integration 

Yang Cao, a professor in the School of Engineering, is working on a three-year ARPA-E project to create a new technology that will help stabilize the power grid and integrate renewable energy sources into the existing energy infrastructure. 

Substations are sprawling networks of wires, towers, and transformers. Substations change the high voltage that comes directly from energy generation stations into low voltage that can safely be delivered to homes or businesses. 

The century-old energy infrastructure in the United States is prone to power outages, especially during increasingly common severe weather. 

This infrastructure is also poorly suited to renewable energy sources as they were designed for fossil fuels. 

With something like wind or solar energy, the energy sources are spread out across a huge expanse rather than coming from a neatly packaged oil barrel. Solar panels or wind turbines also tend to be in remote areas far from major cities that have massive electrical needs. This means we need more efficient technologies that can link distributed energy generators to urban areas. 

Cao will work with Virginia Tech on the project, titled Substation in a Cable for Adaptable, Low-cost Electrical Distribution (SCALED), to develop high-voltage cables to replace bulky substations. 

“We need a more versatile and compact conversion and integration solution for distributed renewable energies,” Cao says. “This overall project is targeting that.” 

Making something this compact will be highly advantageous as they can be placed almost anywhere, whereas current substations require a tremendous amount of open space. 

The goal of the project is to greatly reduce the footprint of substation technologies without compromising its effectiveness. 

“We could really have a very compact substation that helps to convert and integrate the distributed energy generation into a grid instead of having really large, bulky substations,” Cao says.  

A Better Path for New Materials 

James N. Hohman
Dr. J. Nathan Hohman

Nate Hohman, assistant professor of chemistry, is working on a new DOE grant to develop artificial intelligence (AI) tools to improve the synthesis of new materials. 

While scientists are constantly innovating new materials for energy, biotechnology, and many other applications, currently, the best tool they have at their disposal for this process is trial and error.  

“Engineering a new hypothetical material today requires guesswork at every step,” Hohman says. “We guess what compounds might crystallize into a structure that may have a property of interest, hope we get the material we expected, and pray it has the properties we imagined. This is inefficient, labor intensive, and has a low likelihood of success.”  

Hohman will combine nano-crystallographic characterization with Euclidean neural networks to develop a better technique for real-time characterization of materials using a continuously variable model material system.  

Crystal characterization allows scientists to see how the atoms that make up a molecule are arranged. This information is critical for designing new materials as this structure is what determines what the material can do.  

Hohman recently found a way to study crystal structure using an X-ray beam. This allowed his team to capture a crystal’s single diffraction pattern and merged them into a data set they can use to determine the atomic structure. This speeds up the process of characterizing new materials from months or even years to just hours.  

Euclidean neural networks are artificial neural networks inspired by the human brain. A set of artificial neurons transmits signals to other neurons in the system in order to classify objects. Hohman’s collaborator Tess Smidt at MIT developed Euclidean neural networks that can handle 3-D geometries, like those of molecules.  

Hohman in collaboration with other synthetic materials scientists, computational crystallographers, and deep learning researchers will use these networks to train machine learning algorithms to predict new phases of materials. This will help eliminate guesswork from materials development.  

Hohman will have the neural networks will help scientists design and generate novel atomic geometries with desirable properties based on what the scientists want the material to do.  

Designing for High Heat 

Julian Norato
Dr. Julián Norato

Julián Norato, associate professor of mechanical engineering, is working on an ARPA-E grant to develop computational techniques to design highly efficient and compact heat exchangers. 

Heat exchangers are mechanical devices that transfer heat from a hot to a cold fluid. They are found in everything from air conditioners to space heaters to chemical plants to airplanes. 

The heat exchangers Norato’s group will focus on operate at temperatures above 1100 degrees Celsius (approximately 2000 degrees Fahrenheit). These high-temperature heat exchangers are used in many applications, including gas turbine engines, waste heat recovery and hydrogen production. 

The grant will focus on plate-and-frame heat exchangers, which consist of stacks of plates bolted together to a frame. The hot and cold fluids flow between alternate plates. Each plate has a pattern of obstacles to the flow embossed on one side. This helps increase the amount of heat transferred from the hot fluid to the plates, and to the cold fluid flowing through the adjacent plates. 

“The fluid is forced to go through the flow structures inside the plates,” Norato says. “Essentially, you’re putting obstacles to the fluid to force it to mix and spend more time going from the inlet to the outlet of the plate.” 

What these obstacles look like will determine how efficient the heat transfer is. The computational techniques that Norato’s group will formulate will determine the optimal shape and pattern of these obstacles to maximize the heat transfer. At the same time, the design must ensure the pressure drop the fluid experiences as it flows through a plate is kept to a minimum, and that the plates can sustain the pressure the fluid exerts at the high operating temperatures. 

The researchers are also interested in making the device as small and light as possible, which is especially important in aerospace applications that have space and weight restrictions. 

The project will be conducted in collaboration with Altair Engineering, whose computational fluid dynamics software the researchers will use to simulate the heat transfer and the mechanical behavior of the heat exchanger. 

Norato will also collaborate with researchers from Michigan State University, who have developed an additive manufacturing technique to efficiently 3D print the heat exchanger plates out of a metal alloy that can operate at high temperatures. They will 3D print the plate designs obtained by the computational techniques developed by Norato and test the performance and integrity of the heat exchanger in an experimental setup.