Tag: Physics

Published in Tech Today

by Marcia Goodrich, senior writer

Electronic gadgetry gets tinier and more powerful all the time, but at some point, the transistors and myriad other component parts will get so little they won’t work. That’s because when things get really small, the regular rules of Newtonian physics quit and the weird rules of quantum mechanics kick in. When that happens, as physics professor and chair Ravindra Pandey puts it, “everything goes haywire.”

Theorists in the field of molecular electronics hope to get around the problem by designing components out of a single molecule. Pandey’s group has done just that–theoretically–by modeling a single-molecule field-effect transistor on a computer.

“Transistor” has been an oft-used but rarely understood household word since cheap Japanese radios flooded the US market back in the 1960s. Field-effect transistors form the basis of all integrated circuits, which in turn are the foundation of all modern electronics.

A simple switch either diverts current or shuts it off. Transistors can also amplify the current by applying voltage to it (that’s how amplifiers work).

A diagram of Pandey’s three-terminal single-molecule transistor looks like an elaborate necklace and pendant, made up of six-sided rings of carbon atoms bedecked with hydrogen and nitrogen atoms. His group demonstrated that the electrical current running from the source to the drain (through the necklace) rises dramatically when voltage applied at the gate (through the pendant) reaches a certain level.

This happens when electrons in the current suddenly move from one orbital path around their atoms to another. Or, as Pandey says, “Molecular orbital energies appear to contribute to the enhancement of the source-drain current.”

Their virtual molecule may soon exist outside a computer. “Several experimental groups are working to make real our theoretical results,” says Pandey.

An article on the molecular transistor, “Electronic Conduction in a Model Three-Terminal Molecular Transistor,” was published in 2008 in the journal Nanotechnology, volume 19. Coauthors are physics graduate student Haiying He and Sashi Karna of the Army Research Lab.

Tech Today

by Jennifer Donovan, public relations director

Ulrich Hansmann, professor of physics and leader in computational and biophysics research, has received the 2009 Michigan Tech Research Award.

He developed seminal numerical techniques for modeling the workings of living cells and led efforts to apply computational algorithms to protein physics. He recently was named a Fellow of the American Physical Society (APS), a recognition of excellence by his peers and one of the highest honors in his field.

Hansmann is a pioneer in computational modeling of protein folding, a molecular process that, when it goes awry, can give rise to neurological diseases such as Alzheimer’s. His work could help uncover the underlying processes causing proteins to misfold, potentially leading to effective therapies.

“Uli’s achievements in the protein-folding problem–one of the most significant challenges in science today–have been astonishing,” Robert H. Swendsen, professor of physics at Carnegie Mellon University, remarked.

“Uli is one of Tech’s leading computational scientists, with his outstanding work and international reputation among leaders in his field,” said David Reed, vice president for research. “He has taken the lead in trying to build computational capacity at Tech, and we look forward to continued advancement in this area through the current Strategic Faculty Hiring Initiative in computational discovery and innovation.”

Ravindra Pandey, chair of the physics department, also had high praise for Hansmann. “We are extremely proud of Professor Hansmann’s achievements in computational biophysics,” Pandey said. “He is an internationally known scientist in protein folding. He has established a well funded research group here at Michigan Tech and conducts extremely productive collaborative work with several national and international research groups.”

A leader in a computational approach to understanding the complex interactions in biological systems in a new, interdisciplinary field known as systems biology, Hansmann organized three international workshops on computational biophysics in systems biology. While continuing to teach and do research at Michigan Tech, he also helped the John von Neumann Institute for Computing in Jülich, Germany, develop a computational biology and biophysics research group.

“Not all key processes or molecules are accessible by experiments; simulations are sometimes the only technique to detect hidden processes or proteins,” Hansmann explained. “A systems biology approach that aims at deciphering the life functions in a cell requires a close interplay between experiments and computing.”

The physicist’s research goals include analysis and interpretation of biological data through modeling of molecular networks and simulation of cellular biophysics. He hopes this will enable scientists to analyze and predict complex diseases at a molecular level.

Although Hansmann is doing cutting-edge work, he is in no way proprietary about it. He already has developed a software program called Simple Molecular Mechanics for Proteins (SMMP) that is freely available as open source software on the Internet. One of his ongoing research goals is to develop public software for molecular simulation of cells.

As a teacher, Hansmann is devoted to helping students from a variety of fields, including physics, computer science, chemistry and biology, learn how to use supercomputers in their research. He also mentors community college students from underrepresented and disadvantaged populations through the Michigan Colleges and Universities Partnership (MICUP) program at Michigan Tech.

Born in Germany, Hansmann received his PhD in Physics from Freie Universität in Berlin. He has taught physics at Michigan Tech since 1998. His research is supported by the National Science Foundation.