On Professor Roop Mahajan's 80th Birthday

Roop Mahajan was born on Mar. 5, 1944, in Jassar, a small town near Sialkot (now in Pakistan). His family was reportedly affluent, owning vast tracts of agricultural land and small businesses that his father had inherited. However, the partition of India in 1947 upended this cozy living, forcing his family to relocate to Gurdaspur, a district town in postpartition India, near the border. Like many families affected by partition, the family was forced to rebuild their lives amidst the turmoil of partition. Recognizing that education was the key to future opportunities, his parents impressed upon their children the importance of academic excellence. Guided by this ethos, Roop dedicated himself wholeheartedly to academics, to the exclusion of extracurricular activities, and that single-minded devotion allowed him to achieve notable academic milestones, such as skipping grades in primary school and ranking fourth among hundreds of thousands of students in a state-wide high school examination at the age of 14. His siblings also excelled in academics; his elder brother would go on to become a professor at the prestigious Indian Institute of Technology, Kanpur.

Driven by a natural aptitude for mathematics, Roop pursued an intermediate degree in pre-engineering, laying the foundation for his future engineering profession. He established a record of academic performance in the district and earned a top four state-wide ranking. He attended the Punjab Engineering College in Chandigarh, a premier legacy college renowned for its strong engineering programs since its establishment in Lahore, Pakistan in 1921, from where he graduated in 1964 with a Bachelor of Engineering degree in mechanical engineering with distinction and a top university ranking (Fig. 1).

After graduation, Roop joined the American Refrigerator Company in Calcutta (now Kolkata), India as a management trainee, before transitioning in 1965 to a teaching role as an assistant professor in mechanical engineering at his alma mater, Punjab Engineering College. Over the next seven years, he dedicated himself to teaching and research while concurrently pursuing a master's degree in Rotodynamics, graduating with distinction in 1969 and setting a university record that has stood unchallenged to this day.

Driven by a thirst for knowledge and spurred by familial influences, Roop desired to emigrate to the U.S. for doctoral studies. Fortunate to have received multiple offers, he joined the Sibley School of Mechanical and Aerospace Engineering at Cornell University in 1972, where he worked under the guidance of Professor Benjamin Gebhart, a giant in the field of buoyancy-induced flows and transport. His doctoral thesis was a combination of experimental and analytical work focused on understanding the phenomena of transition from laminar to turbulence in buoyancy induced flows adjacent to a vertical surface. Major contributions included a new physics-based criterion for the onset of transition in gases that departed from the conventional wisdom of using Grashof number as an indicator of transition. It was argued that Grashof number, as indicated by the linear instability theory, cannot accurately be a predictor of turbulence, which is essentially characterized by nonlinear growth of high amplitude disturbances. A new parameter, a modified Grashof number related to the kinetic energy of the flow, was proposed. It was shown that the wide range of transition Grashof numbers reported in past studies collapsed around a single value of the new parameter with remarkable consistency. Other contributions include the first-ever experimental study of laminar film condensation for fluids with Stefan or Jakob numbers greater than 1, and an elegant analysis for terrestrial flows that showed the viscous dissipation effect is always smaller than the pressure effect for all values of Prandtl number.

Professor Yogesh Jaluria, a stalwart in the domain of Heat Transfer and Roop's lab-mate, apartment mate from Ph.D. days (Fig. 2) recalls their long association and friendship of over 40 years. “I have known Roop for over four decades as a fellow student under the same Ph.D. advisor, apartment mate, coauthor, and, above all, as a close and trusted friend. We overlapped in our research on many topics. Our doctoral theses were also in the same area. We were coauthors on an extensive treatise on buoyancy-induced flows with our mentor, Professor Benjamin Gebhart, (Fig. 3) and worked closely over several years. So, clearly, we have a lot of great memories and enjoyable moments. We share a love of Indian culture, philosophy, music, movies, and literature. To me, Roop is a warm, friendly, kind, and generous person, who can make friends with anyone in a moment. I remember hours spent in discussions on a wide variety of topics and we could have gone on forever. He has accomplished a lot professionally and is well known in the engineering community for his work. But even greater than his achievements, his empathy, generosity, decency, and kindness make him a wonderful person.”

Upon completion of his doctoral studies from Cornell in 1976, Roop joined AT&T Bell Labs Engineering Research Center in Princeton, NJ, where he served as a Member of Technical Staff from 1976 to 1979 and later as an MTS-Research Leader from 1979 to 1991. He established himself as an outstanding technology leader in the domain of semiconductor packaging, manufacturing, and system integration, conducting compelling research on transport processes in semiconductor manufacturing, such as silicon crystal growth, chemical vapor deposition, two-phase flows, convective instability, and electronic cooling. His major contributions included the development of closed single vapor- and in-line vapor phase heating technology for mass solder reflow applications, original work in silicon epitaxy, Czochralaski crystal growth and thermal management in electronic switching systems.

In 1989, Roop was elevated to the rank of Bell Labs Fellow, the highest technical ranking, in recognition of his enduring contributions to the field. Perhaps even dearer to his heart was the AT&T Technical Journal Great Boss Award that he received in 1988, which was based on the employee nominations, reflecting a leader's capabilities to motivate, lead, care, and accomplish.

The eventual divestiture of AT&T, coupled with his longing for academia, led Roop to return to academia. In 1991, he joined the University of Colorado, Boulder, CO (CU Boulder) as a Professor of Mechanical Engineering, with a mission to conduct and spearhead interdisciplinary research at the cutting edge of technology and to inspire the next generation of engineers with a fervent dedication to excellence and societal impact. This transition marked a new chapter in his career, one defined by a commitment to advancing knowledge and innovation within the academic realm (Fig. 4).

Over the next 15 years (1991–2006) at CU Boulder, Roop established himself as an outstanding teacher and academic researcher shaping the careers of many students and junior colleagues. He conducted ground breaking research in diverse areas spanning across thermal sciences, artificial neural networks (long before artificial intelligence became the buzzword), nanotechnology, bio-micro-electro-mechanical systems or bio-micro-electromechanical systems (MEMS) and humanistic engineering; a set of diverse fields underlining his versatility and ability to make solid contributions in a new field in a relatively short period of time.

In 1992, he founded the interdisciplinary research Center for Advanced Manufacturing and Packaging of microwave, optical, and digital electronics (CAMPmode) involving faculty and students from mechanical, electrical, materials, and aerospace disciplines that went on to become an NSF-Industry/University Cooperative Research Center in 1995 with an annual budget of USD 2 million. The center slowly evolved into a leading center of research on MEMS, which later expanded to include an initiative on nanotechnology for engineering and life sciences. This was followed by the Center for Micro-Electronic Devices in Cardiovascular Applications, an interdisciplinary center between CU-Health Sciences Center and the College of Engineering and Applied Sciences, CU Boulder that he cofounded in 1999. Its mission was to foster excellence and scientific advancement in the study and application of MEMS in cardiovascular applications. Besides seeding a spinoff company, Cardiac Assist, the center developed smart stents and heart valves, and self-deploying memory polymer neuronal electrodes.

Both CAMPmode and Micro-Electronic Devices in Cardiovascular Applications left indelible marks in the research landscape of CU Boulder resulting in significant contributions in semiconductor packaging technologies, MEMS and sensors, pediatric cardiology in addition to fundamental advancements in science and technology. Apart from leading these research centers, Roop's own research group flourished resulting in 14 doctoral and 12 masters theses supervisions. His work on transport phenomena on high porosity media led to several seminal publications in leading journals that have been extensively cited. Five of these papers have garnered close to 4500 citations till date. Recognitions followed and flowed with elevation to ASME Fellow (1997), Boulder Faculty Assembly Award for Excellence in Research, Scholarship and Creative Work (1998–1999), Subaru Educator of the Year Award (2002), ASME Heat Transfer Memorial Award (2002), and ASME Charles Russ Richards Memorial Award for outstanding achievement in mechanical engineering (2003).

Professor Y. C. Lee was Roop's mentee at Bell Labs. He joined CU Boulder in 1989 and soon played a pivotal role in recruiting his mentor. Over the next 15 years the Roop-YC duo did wonders at CU-Boulder. “Roop has been my mentor since the beginning of my professional career in Bell Labs in 1984. After I moved to the CU Boulder in 1989, I recruited Roop to join us as my boss and established the NSF CAMPmode in 1992. Roop knew how to talk with a vision, and I knew how to recruit industrial sponsors. CAMPmode was recognized as a leading packaging research center in the U.S. Our groups collaborated on a number of research projects including metal foam heat sinks and use of artificial intelligence tools for process control. In 1998, we expanded the scope of CAMPmode to cover MEMS. Roop left CU for Virginia Tech in 2006. In that year, I worked with other faculty and established the DARPA Center for Integrated Micro/Nano-Electromechanical Transducers (iMINT). How did I run this center? No problem. I followed my mentor's footsteps and applied his management procedures established for CAMPmode to run iMINT. I am blessed to have Roop as my mentor, and I am fortunate to witness and support Roop's truly outstanding research, teaching, and service.”

During this phase, Roop also served as Interim Dean of the College of Engineering and Applied Science during 2001–2002 (Fig. 5) where he started several initiatives toward improvement in research, instruction, diversity, and service to the community by a factor of two in 6 years, some of which are still followed today.

While most people would like to have a restful life after 60 and after having achieved so much, the organization builder in Roop Mahajan was still not done. The incessant thirst to build world class organizations coupled with his uncanny ability to recruit the best and brightest around him, drove him to Virginia Tech in 2006 as the founding Executive Director of the Institute for Critical Technology and Applied Science (ICTAS), an organization that he led for a decade till 2016 (Fig. 6).

Under his leadership, ICTAS grew to be a premier institute for transformative research intersecting engineering, the sciences—physical, life, and social, and humanities for a sustainable future. Researchers from across the campus with expertise in their underlying disciplines but with a passion for interdisciplinary research and a vigilant eye for new, unprecedented discoveries were pulled together to make advances, develop and implement path-finding solutions for discovery analytics, cyber security, energy harvesting materials and systems, sustainable nanotechnology, sustainable water, autonomous systems, and macromolecules and interfaces. From its modest beginnings in 2006 with a skeleton staff and a few rented offices at the Virginia Tech Corporate Research Center, ICTAS grew to almost 200,000 square feet of footprint spread over three buildings on the main campus in Blacksburg, VT Research Center in Arlington, VA, and an Innovation Center in Chennai, India. At the time of his stepping down, ICTAS was home to more than 20 interdisciplinary research centers spanning across diverse areas. In fiscal year 2015 alone, 335 ICTAS supported faculty from across the campus, secured over $112M in research grants that included support for 182 doctoral students.

Professor Richard Benson, former Dean, College of Engineering at Virginia Tech and now President, UT-Dallas, who was instrumental in hiring Professor Mahajan in VT recalls his long and memorable association in the following words. “One of the greatest hires that I have made at any point in my now-long career—was to employ Roop Mahajan in 2006 to serve as the first permanent director of ICTAS at Virginia Tech. What Roop was able to achieve in the next 10 years is almost beyond comprehension. Apart from the infrastructure, he established every protocol for advancing Virginia Tech's research portfolio, with a special emphasis on multidisciplinary research. I think often and with admiration about his practice of always having an ‘embedded humanist’ on his own research team. Further adding to the joy of being Roop Mahajan's colleague is sharing the breath of his curiosity. We celebrate his engineering successes of course, but know too, that you will not find a person of broader intellect, nor a person of greater kindness.”

Professor Ishwar Puri, Senior VP of research and innovation and professor of Aerospace and Mechanical Engineering at University of Southern California, fondly remembers his association with Roop during their VT days. “It is a profound honor to celebrate Professor Roop Mahajan's 60 years of pioneering scholarship. In 2006, I was privileged to play a role in recruiting Professor Mahajan to Virginia Tech as Director of ICTAS and Lewis A. Hester Chair Professor. His visionary approach and interdisciplinary research spanning nanotechnology, biomedical engineering, and sustainability have earned him numerous accolades, foremost among them the ASME Heat Transfer Memorial Award and the Ralph Coats Roe Medal. Professor Mahajan's contributions have profoundly impacted engineering research and education, making him a revered figure in the scientific community and role model for unwavering dedication and exceptional achievements.”

After stepping down as Executive Director of ICTAS in 2016, Roop has continued to serve as its global ambassador forging collaborative relationships with international institutions engaged in interdisciplinary and transformative research. One of the most significant outcomes of his efforts have been the Virginia Tech India Research and Education Forum, also known as Virginia Tech India, with its headquarters in Chennai, India. This global outreach center houses a state-of-the-art research laboratory dedicated to leading edge research in a few areas of synergistic relevance to both U.S. and India. He has guided the laboratory's development from planning and design to the selection of research projects, where he personally leads a cutting-edge research program on graphene and its derivatives. In addition, he has also been instrumental in setting up partnerships in China, Japan, and Egypt.

Professor Shashank Priya, Roop's former colleague at VT and now Vice President for Research at University of Minnesota was one of Roop's direct mentees. “I am fortunate to have Professor Mahajan as my life-long mentor. I can cite many lessons that I have learned from him over time but here are the three that guide me everyday: (i) new knowledge originates when researchers from different disciplines are provided an environment to explore a new space together. Incentives have to be aligned in a manner that compels the researchers to take the risk. (ii) Each researcher should dedicate some percent of their time (e.g., 20%) to continuously explore a new domain, something that qualifies for a high risk high reward. (iii) Invest in people and their vision. It takes time to realize a transformative vision; so be patient and not get bound by annual deliverables.”

Roop was named as the Inaugural Thapar Chair Professor for Emerging Materials at Thapar Institute of Engineering and Technology, a well-known private university in India focusing on engineering and technology in 2016. Here also, he left his mark as a “builder,” successfully establishing a ground-breaking interdisciplinary research “Center of Excellence on Emerging Materials” that today boasts a team of over 75 faculty members and 32 research scholars working on different research projects, strategically designed to leverage the superior properties of advanced materials.

In the words of Professor Rajeev Mehta, Professor of Chemical Engineering at Thapar Institute of Engineering and Technology, “I have had the privilege of closely associating with Professor Mahajan, a truly phenomenal figure in both research and innovation, as well as a kind and gentle human being. His extensive knowledge across multiple fields is incredibly impressive. From Professor Mahajan, I have learned invaluable lessons, including the importance of striving for excellence, thoroughness, and dedication to one's work. His ability to make friends easily is a testament to his warmth and genuineness.”

In addition to his professional accomplishments, Roop is deeply committed to both his family and community.

He has served as a role model and inspirational leader for students and faculty alike, encouraging them to extend their expertise beyond the confines of classrooms and laboratories to serve both local and global underserved communities. At Virginia Tech, his infectious optimism and inspiring leadership were instrumental in the establishment and advancement of Service Without Borders, an interdisciplinary, student-led organization that provides students with real world design, project management, technical writing, construction, marketing, and fund-raising, locally and globally. In the words of Abigail Smith, the Founding Student President, “We are so grateful to have you as a mentor and someone who always leaves our minds spinning with ideas for the future of Service Without Border!”

During his time, Roop served as a faculty advisor for the Association for India's Development-Blacksburg Chapter, in its endeavor to support grassroots organizations in India throughout education, livelihood, natural resources management, agriculture, health, women's empowerment, and social justice sectors. He demonstrated active leadership and personal commitment in guiding students to expand Association for India's Developments impact by forging collaborations with local nonprofit organizations and educational institutions in India. A noteworthy initiative has been his sustained efforts to assist the Agariyas, a community of salt workers struggling for survival in the desert region of The Little Rann of Kutch in Gujarat, India. Another notable initiative involved replacing diesel-powered pumps that pump underground seawater, with environmentally friendly, economical solar-powered pumps.

Since the 1980s, Roop and his family have also devoted themselves in the Bal Vihar (Sunday school) program, tailored for American children of Indian descent. Meaning “joy for children,” Bal Vihar is a cornerstone of cultural education and community cohesion. The Mahajans initially spearheaded this initiative in Princeton, NJ, and continued upon their relocation to Boulder, CO, in 1991 with support from members of the local community.

In addition to being a devoted husband and father of three remarkably talented children (Fig. 7), Roop finds solace and enrichment in pursuits such as hiking, reading, and meditation. His multifaceted interests and active engagement in various national and international endeavors underscore his well-rounded personality and dedication to both personal and professional growth.

For former students and junior colleagues, Professor Roop Mahajan has not only been a dear supervisor or collaborator but also a lifelong mentor. Many of his students, who are all well-established today in their own ways, remember the profound influence of their mentor in their lives and careers.

Dr. Vara Calmidi, one of his early Ph.D. students in CU-Boulder and now Senior Director at Microsoft USA based in Seattle, paid his tribute. “It is my honor and pleasure to celebrate Professor Mahajan on his 80th birthday. I am filled with gratitude for what I learnt as his Ph.D. student at the University of Colorado. Starting with the basics of heat transfer to tackling the intricacies of transport phenomena in metal foams, he made sure that I was focusing on the problem at hand, but also that I had all the right experiences needed for a successful career. Above all, his advice and wise counsel on how to approach scientific problems and how to think holistically has inspired me throughout my career as a mechanical engineer, a thermal engineer, and a reliability engineer. May his wisdom and mentorship touch many more students and scholars.”

Dr. Ming Yi, a former Ph.D. student and postdoctoral scholar, and now Policy Director with Intel China, remembers his mentor “I am extremely honored to have been a Ph.D. student and postdoctoral researcher under Professor Roop Mahajan. During this period, I was deeply moved by the professor's extensive knowledge and his enduring spirit of exploration. His guidance inspired me not only in the traditional field of heat transfer but also in the scientific research of medical applications, artificial neural networks, and nanotechnology, motivating me to continuously learn and explore cutting-edge science. I will always remember the meticulous revisions he made to every word and sentence for my research papers. My first research paper went through more than 30 revisions by him, which taught me firsthand how to think critically in research and how to communicate effectively in academia.”

Professor Gurpreet Singh, former Ph.D. student and postdoctoral scholar, and now Chair professor at Kansas State University (Fig. 8), still calls upon his mentor regularly. “Professor Mahajan's legacy is not just in his vast knowledge of the heat transfer but also numerous technical and administrative contributions to the field of nanotechnology. He has an amazing ability to anticipate emerging technologies and how to be there first. During those nascent stages of nanotechnology, we developed innovative methods for separation of individual carbon nanotubes and studied vapor or gas bubble formation on their surfaces among many other things. Nanotechnology was prohibitively expensive back then and experiments failed frequently. I was fortunate that Professor had a big heart for experiments that did not work; he encouraged me to learn from those failures and be better.

Later as his postdoc at Virginia Tech, I became acquainted with the profound human and spiritual side to Professor Mahajan. He was not hesitant to take significant chances with those who were less favored; routinely offering opportunities to underprivileged or disadvantaged individuals. He was generous with his time to those who needed that additional assistance. As a faculty member, I have learned to promote a culture of diversity and openness where mixed experiences are valued. Professor Mahajan taught me to recognize strengths in others rather than dwelling on shortcomings. Just as Professor Mahajan would say ‘The more, the merrier,’ I have understood the power of collaborative proposal writing and joint publications.”

In the words of another former Ph.D. student, Dr. Hrishikesh Panchawagh, now Principal Engineer/Manager with Qualcomm USA, “It has been an honor and privilege to have Professor Roop L. Mahajan as my Guru, not only during my graduate studies at University of Colorado in Mechanical Engineering but throughout my life ever since. Professor Mahajan exemplifies a coach and mentor in every aspect including top-notch academic excellence and rigor, constant drive to push to new limits, highest ethical standards, compassion, and spirituality. Professor Mahajan's numerous accolades in the fields of heat transfer and transport phenomenon, as well as electronics packaging and manufacturing are well known. In addition, one of his most admirable qualities is his eternal optimism and ability to make an impact in new frontiers of science and engineering. I had the fortune to be part of one such initiative by Professor Mahajan, Cellular Engineering Microsystems which focused on microdevices that can investigate single biological cells. His research in diverse fields has inspired researchers around the world and has made an everlasting impact. Most importantly, Professor Mahajan strives to apply engineering advances for the benefit of humanity.”

Chetan Malhotra did his MS under Professor Mahajan during 1996–1998 before returning to India. While leaving he had said to his lab-mates that if he ever came back to USA for a Ph.D., he would only do it under Professor Mahajan. Chetan kept his word and returned 4 years later to CU Boulder for his doctoral studies. Now a Principal Scientist with TCS Research in Pune, India, he recalls his association in the following words. “It was a day in March 1996 when I received a letter from Professor Mahajan offering me an assistantship at the University of Colorado. That day changed my life. From being an ordinary engineering student in Pune, India, I went on to pursue a Masters and a Ph.D. with a decorated ASME Fellow. This instilled in me a lifelong passion for learning, critical thinking, applying scientific method, and mentoring. The last passion is a direct result of me observing Professor Mahajan over the years. Simply put, he took everyone along. He gave you pointers on what would be a good problem and a good approach to tackle it but left it to you to figure out the details. But at every stage, he was always there to guide you, to mentor you and most importantly, to support you even during failures. I cherish every moment, I have spent with Professor Mahajan and thank the universe for making him take me under his wings.”

Professor Prashant Singh, now faculty at University of Tennessee at Knoxville, TN was associated with Professor Mahajan in VT as his postdoctoral scholar. “My past and ongoing research is inspired from his vast experience and in-depth knowledge in thermal-fluid science. He has been a great mentor to me and has guided me on research, life in academia and otherwise. I cherish our association as collaborators, and it is my privilege to have him as a mentor. Professor Mahajan's energy and excitement about research in diverse areas, and his unique mentorship and nurturing nature toward young scientists is a source of inspiration for me.”

Professor Mantha S. Phanikumar, Professor of Civil and Environmental Engineering at Michigan State University, who collaborated with Professor Mahajan, notes: “I am grateful for my collaboration with Professor Mahajan. His enthusiasm and dedication to research are nothing short of infectious. His friendly smile and demeanor create an inviting atmosphere that encourages dialogue and collaboration. Professor Mahajan leads by example, demonstrating that success in academia is not just about research excellence but also about fostering a supportive and collaborative environment.”

The above testimonials underline Roop Mahajan, not only as an outstanding and versatile researcher and technology leader but also underlines his qualities as a remarkable human being. His ability to mentor, to bring out the strengths in everyone and above all, stand behind as a pillar of support even during failures, has been a life lesson for all (Fig. 9).

Professor Roop Mahajan's remarkable professional journey has spanned close to six decades in which he has made seminal contributions to multiple and diverse research areas such as convective flows, transport phenomena in semiconductor manufacturing, electronic packaging, artificial neural networks, humanistic engineering, bio-MEMS, nanotechnology, and advanced materials. In recognition of his outstanding contributions, he has been bestowed with prestigious awards and recognitions.

Above all, however, he will be remembered as a remarkable technology leader who understood the true calling of his profession to “harness the basic principles of science and engineering to do something useful for society.” Through his own research, he has demonstrated the abiding power of this principle by seamlessly integrating his laboratory innovations to the society. He fundamentally believes in the interconnectedness of world communities to address the grand challenges facing humanity, from meeting basic needs to ensuring a sustainable future.

The essence of his research philosophy is best captured in his own favorite opening line for many of his talks: “Research is global, education is global, and without any doubt, our future is global.”

This guest editorial is a tribute to his rich legacy. May Almighty bestow him with many more years of happy and healthy life ahead!