Month: November 2024

12.6.24 Dr. Sotiris E. Pratsinis – ETH Zürich

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From aerosol synthesis of materials and devices to a new kinetic theory of gases?

Date: December 6, 2024; Time: 2:00 PM Location: PWEB 175

Abstract: Recent advances in understanding of combustion and aerosol formation and growth through multiscale process design, allow now inexpensive synthesis of nanoparticles with sophisticated composition, size and morphology by spray combustion at kg/h even at academic institutions with such units now all over the world (UK, Spain, India etc.). These have led to synthesis of single noble atom heterogeneous catalysts, biomaterials and highly porous sensing films. These advances and community’s keen interest on nanoscale phenomena have motivated a closer look to the fundamentals of aerosol particles in the free molecule regime.

For eons, the kinetic theory of gases has been assuming elastic collisions between spherical gas molecules [1]. However, is this so with what we know about molecular shape and force fields today? Having reached a state of maturity now, molecular dynamics (MD) simulations can elucidate the fundamentals of basic aerosol phenomena that lead to better understanding of natural phenomena and accelerate process design and scale-up [2].

Here the mechanics of gas collisions are elucidated for plain air at room temperature by thoroughly-validated atomistic MD treating O2 and N2 as true diatomic molecules accounting for their shape and force field, for the first time to our knowledge. So it is revealed that their trajectories are no longer just straight (or ballistic) while collision frequencies are much higher due to the attractive component of the force field and the diatomic shape of N2 and O2 as will be shown by the respective videos. Frequently, colliding molecules were split from each other but soon return to collide again and again without interacting with any other molecule in between resulting in orbiting collisions as had been envisioned 60 years ago [3].

A direct result of the enhanced interactions between air molecules when treated as true diatomic ones is that their mean free path (MFP) comes out to be considerably smaller than that from the classic kinetic theory. The new MFP for air is 38.5 nm, almost 43% smaller than that in textbooks of 67.3 nm at ambient conditions [4]. Such a result is significant in aerosol synthesis of tiny (< 5 nm) nanoparticles where asymptotic (self-preserving) particle size distributions and (fractal-like) structures have not been attained yet to simplify the corresponding process design as with carbon blacks and fumed oxides today.

Most importantly, this motivates a renewed examination of aerosol dynamics in the free molecular regime. If time permits, it will be shown that accounting for the gas molecule shape and force field (in addition to that of particles) drastically decreases the diffusivity of tiny aerosol nanoparticles, up to an order of magnitude lower than that given by Epstein’s equation in all aerosol textbooks as their size approaches that of surrounding gas molecules.

  1. Maxwell JCMA, The London, Edinburgh, Dublin Philos. Mag. J. Sci., 19-32 (1860).
  2. Mavrantzas VG & Pratsinis SE, Curr. Opinion Chem. Eng., 23 174 – 183 (2019).
  3. Hirschfelder, JO, Curtiss, CF, Bird, RB, Molecular Theory of Gases & Liquids, Wiley, 1964.
  4. Tsalikis D, Mavrantzas VG, Pratsinis SE, Aerosol Sci. Technol. 58, 930 – 941 (2024).

Biographical Sketch: Dr. Pratsinis has a 1977 Diploma in Chemical Engineering from Aristotle Univ. of Thessaloniki, Greece and a 1985 PhD from Univ. of California, Los Angeles. He was in the faculty and head of ChE at the Univ. of Cincinnati, USA until 1998 when he was elected Professor of Process Engineering & Materials Science at ETH Zurich, Switzerland. He has graduated 46 PhDs, published 400+ refereed articles, filed 20+ patent families that are licensed to industry and have contributed to creation of four spinoffs. One of them (HeiQ Materials AG) was the first ever from ETH Zurich to enter the London Stock Exchange in December 2020. Another one (Alivion AG) was launched in 2022 and has sold already its devices for detection of adulterated alcohol and methanol poisoning in 26 countries. For more details on him you may glance at https://ptl.ethz.ch/people/person-detail.html?persid=79969

New Models Help Predict Protein Dynamic Signatures

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by Ira Morrison

This breakthrough in accurately predicting protein crystallization propensity is vital for developing drugs and understanding diseases

A new computational model and tool developed at UConn uses advanced techniques to analyze protein dynamics and predict their crystallization propensity accurately. (Christopher LaRosa/UConn Photo)

To the average person, knowing how a protein wiggles might not seem that exciting or pertinent, but then again, most people aren’t fascinated by the natural movements and fluctuations of proteins and their functional properties. If, however, you were interested in designing new drugs, better understanding how diseases can be eradicated or enhancing biotechnology for industrial and therapeutic applications, you might be on the edge of your seat waiting to see what a new study on protein sequencing and crystallization has to offer.

An article about that study, authored by Anna Tarakanova, assistant professor in the School of Mechanical, Aerospace, and Manufacturing Engineering at UConn’s College of Engineering, has just appeared in a prominent monthly scientific journal, Matter, which focuses on the general field of materials science. The study examines how the natural movements and fluctuations of proteins – the protein’s “wiggles” – can help predict their functional properties. Tarakanova was assisted by Mohammad Madani, a Mechanical Engineering graduate student and first author of the study.

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Dr. Stephanie Santos, an MAM alumna, named to the Vergnano Endowed Chair for Inclusion

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by Ira Morrison

Stephany Santos, named to the newly established Vergnano Endowed Chair for Inclusion, sees her role as helping students build successful engineering futures, no matter the challenges

Professor Stephany Santos at the Vergnano Showcase in April 2024. (Matthew Hodgkins/UConn Photo)

Stephany Santos, the new Vergnano Endowed Chair for Inclusion at UConn’s College of Engineering, feels like she’s been preparing for this role since she set foot on UConn’s campus in 2008, as an undergraduate preparing to study mechanical engineering.

Prior to her first summer at UConn, she was a participant in the BRIDGE program, which is a transitionary preparation program designed to support the success of incoming first-year students that are underrepresented in engineering.

The BRIDGE program, then run out of the Engineering Diversity Program led by Kevin McLaughlin, became a hallmark of her identity and purpose as an engineering student and leader at UConn, says Santos ’12 (ENG) ’20 Ph.D. She volunteered for every program offered by the Engineering Diversity Program, from Multiply Your Options, a program designed to inspire 8th-grade girls to think about STEM, to the Northeast Regional Science Bowl, the largest regional competition in the country for high school students competing quiz-bowl-style in STEM questions.

During this period Santos also helped found UConn’s student organization Engineering Ambassadors. This is an organization that supports K-12 teachers and education systems by broadening understanding and access to engineering, and by exploring how engineers can change the world for good. These programs, Santos explains, are foundational in creating confidence academically, connections psychosocially and inspiration professionally.

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Mission Complete: Lee Spends 45 Days in NASA Simulated Journey to Mars

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by Olivia Drake – UConn College of Engineering

By participating in the mission, College of Engineering’s Jason Lee contributed to NASA’s efforts to study how future astronauts may react to isolation and confinement during deep-space journey.

College of Engineering Associate Professor-in-Residence Jason Lee, pictured third from left, recently participated in a 45-day simulated space mission at the Johnson Space Center in Houston, Texas. Also pictured are his crew mates, Piyumi Wijesekara, Shareef Al Romaithi, and Stephanie Navarro. (James Blair/NASA)

Jason Lee’s lifelong aspiration to explore outer space became a reality—without ever needing to leave planet Earth.

For 45 days, Lee, associate professor-in-residence in the School of Mechanical, Aerospace, and Manufacturing Engineering, lived in NASA’s Human Exploration Research Analog (HERA) habitat at Johnson Space Center, participating in a simulated journey to Mars.

There, he and three other crew members operated in a constrained environment, completing mission-critical tasks, conducting repairs, viewing Martian landscapes through virtual reality, and making communication attempts with Mission Control.

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Professor Jiong Tang receives the ASME Myklestad Award

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Jiong TangProfessor Jiong Tang, a distinguished figure in the field of mechanical engineering, has recently been honored with the prestigious ASME Myklestad Award in 2024. This award, established by the American Society of Mechanical Engineers (ASME), recognizes individuals who have made significant contributions to vibration engineering, particularly in areas related to analytical methods, experimental approaches, and practical applications in mechanical and aerospace systems. Prof. Tang’s work exemplifies the high standards of innovation, rigor, and impact that the Myklestad Award celebrates, showcasing his commitment to advancing the field of vibration engineering through both fundamental research and practical advancements.

Throughout his career, Prof. Tang has led pioneering research that has transformed understanding and approaches within dynamics and vibration. His contributions span a broad array of applications, including structural health monitoring, smart materials, and robust control systems. His research has not only pushed theoretical boundaries but also driven technological advancements that enhance the resilience, functionality, and safety of mechanical systems in various industries. His work has been particularly influential in aerospace and civil engineering, where precise vibration control is critical for ensuring the structural integrity and performance of complex systems.

This honor not only acknowledges his past accomplishments but also underscores his ongoing contributions to the advancement of engineering knowledge and practice.