Natural Sciences
Showing 421-440 of 1,953 Results
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Shanhui Fan
Joseph and Hon Mai Goodman Professor of the School of Engineering, Senior Fellow at the Precourt Institute for Energy and Professor, by courtesy, of Applied Physics
BioFan's research interests are in fundamental studies of nanophotonic structures, especially photonic crystals and meta-materials, and applications of these structures in energy and information technology applications
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Michael Fayer
David Mulvane Ehrsam and Edward Curtis Franklin Professor of Chemistry
BioMy research group studies complex molecular systems by using ultrafast multi-dimensional infrared and non-linear UV/Vis methods. A basic theme is to understand the role of mesoscopic structure on the properties of molecular systems. Many systems have structure on length scales large compare to molecules but small compared to macroscopic dimensions. The mesoscopic structures occur on distance scales of a few nanometers to a few tens of nanometers. The properties of systems, such as water in nanoscopic environments, room temperature ionic liquids, functionalized surfaces, liquid crystals, metal organic frameworks, water and other liquids in nanoporous silica, polyelectrolyte fuel cell membranes, vesicles, and micelles depend on molecular level dynamics and intermolecular interactions. Our ultrafast measurements provide direct observables for understanding the relationships among dynamics, structure, and intermolecular interactions.
Bulk properties are frequently a very poor guide to understanding the molecular level details that determine the nature of a chemical process and its dynamics. Because molecules are small, molecular motions are inherently very fast. Recent advances in methodology developed in our labs make it possible for us to observe important processes as they occur. These measurements act like stop-action photography. To focus on a particular aspect of a time evolving system, we employ sequences of ultrashort pulses of light as the basis for non-linear methods such as ultrafast infrared two dimensional vibrational echoes, optical Kerr effect methods, and ultrafast IR transient absorption experiments.
We are using ultrafast 2D IR vibrational echo spectroscopy and other multi-dimensional IR methods, which we have pioneered, to study dynamics of molecular complexes, water confined on nm lengths scales with a variety of topographies, molecules bound to surfaces, ionic liquids, and materials such as metal organic frameworks and porous silica. We can probe the dynamic structures these systems. The methods are somewhat akin to multidimensional NMR, but they probe molecular structural evolution in real time on the relevant fast time scales, eight to ten orders of magnitude faster than NMR. We are obtaining direct information on how nanoscopic confinement of water changes its properties, a topic of great importance in chemistry, biology, geology, and materials. For the first time, we are observing the motions of molecular bound to surfaces. In biological membranes, we are using the vibrational echo methods to study dynamics and the relationship among dynamics, structure, and function. We are also developing and applying theory to these problems frequently in collaboration with top theoreticians.
We are studying dynamics in complex liquids, in particular room temperature ionic liquids, liquid crystals, supercooled liquids, as well as in influence of small quantities of water on liquid dynamics. Using ultrafast optical heterodyne detected optical Kerr effect methods, we can follow processes from tens of femtoseconds to ten microseconds. Our ability to look over such a wide range of time scales is unprecedented. The change in molecular dynamics when a system undergoes a phase change is of fundamental and practical importance. We are developing detailed theory as the companion to the experiments.
We are studying photo-induced proton transfer in nanoscopic water environments such as polyelectrolyte fuel cell membranes, using ultrafast UV/Vis fluorescence and multidimensional IR measurements to understand the proton transfer and other processes and how they are influenced by nanoscopic confinement. We want to understand the role of the solvent and the systems topology on proton transfer dynamics. -
Shaghayegh Fazliani
Ph.D. Student in Mathematics, admitted Autumn 2021
BioShaghayegh, my first name, means red poppy in Persian. Here in the US, I go with 'Shay' as a nickname since Shaghayegh might be hard to pronounce! I graduated with a bachelor's degree in mathematics from Sharif University of Technology, focusing on pure mathematics. As of September 2021, I'll be a mathematics graduate student at Stanford University.
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Ben Feldman
Associate Professor of Physics
Current Research and Scholarly InterestsHow do material properties change as a result of interactions among electrons, and what is the nature of the new phases that result? What novel physical phenomena and functionality (e.g., symmetry breaking or topological excitations) can be realized by combining materials and device elements to produce emergent behavior? How can we leverage nontraditional measurement techniques to gain new insight into quantum materials? These are some of the overarching questions we seek to address in our research.
We are interested in a variety of quantum systems, especially those composed of two-dimensional flakes and heterostructures. This class of materials has been shown to exhibit an incredible variability in their properties, with the further benefit that they are highly tunable through gating and applied fields. -
Jessica Feldman
Associate Professor of Biology
Current Research and Scholarly InterestsCell differentiation requires cells to polarize, translating developmental information into cell-type specific arrangements of intracellular structures. The major goal of the research in my laboratory is to understand how cells build these functional intracellular patterns during development, specifically focusing on the molecules and mechanisms that build microtubules at cell-type specific locations and the polarity cues that guide this patterning in epithelial cells.
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Marcus Feldman
Burnet C. and Mildred Finley Wohlford Professor
Current Research and Scholarly InterestsHuman genetic and cultural evolution, mathematical biology, demography of China
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Russell D. Fernald
Benjamin Scott Crocker Professor of Human Biology, Emeritus
Current Research and Scholarly InterestsIn the course of evolution,two of the strongest selective forces in nature,light and sex, have left their mark on living organisms. I am interested in how the development and function of the nervous system reflects these events. We use the reproductive system to understand how social behavior influences the main system of reproductive action controlled by a collection of cells in the brain containing gonodotropin releasing hormone(GnRH)
