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Atlanta, GA, United States

The Georgia Institute of Technology is a public research university in Atlanta, Georgia, in the United States. It is a part of the University System of Georgia and has satellite campuses in Savannah, Georgia; Metz, France; Athlone, Ireland; Shanghai, China; and Singapore.The educational institution was founded in 1885 as the Georgia School of Technology as part of Reconstruction plans to build an industrial economy in the post-Civil War Southern United States. Initially, it offered only a degree in mechanical engineering. By 1901, its curriculum had expanded to include electrical, civil, and chemical engineering. In 1948, the school changed its name to reflect its evolution from a trade school to a larger and more capable technical institute and research university.Today, Georgia Tech is organized into six colleges and contains about 31 departments/units, with emphasis on science and technology. It is well recognized for its degree programs in engineering, computing, business administration, the science, architecture, and liberal arts.Georgia Tech's main campus occupies part of Midtown Atlanta, bordered by 10th Street to the north and by North Avenue to the south, placing it well in sight of the Atlanta skyline. In 1996, the campus was the site of the athletes' village and a venue for a number of athletic events for the 1996 Summer Olympics. The construction of the Olympic village, along with subsequent gentrification of the surrounding areas, enhanced the campus.Student athletics, both organized and intramural, are a part of student and alumni life. The school's intercollegiate competitive sports teams, the four-time football national champion Yellow Jackets, and the nationally recognized fight song "Ramblin' Wreck from Georgia Tech", have helped keep Georgia Tech in the national spotlight. Georgia Tech fields eight men's and seven women's teams that compete in the NCAA Division I athletics and the Football Bowl Subdivision. Georgia Tech is a member of the Coastal Division in the Atlantic Coast Conference. Wikipedia.

Wang Z.L.,Georgia Institute of Technology
Advanced Materials

The fundamental principle of piezotronics and piezo-phototronics were introduced by Wang in 2007 and 2010, respectively. Due to the polarization of ions in a crystal that has non-central symmetry in materials such as the wurtzite structured ZnO, GaN and InN, a piezoelectric potential (piezopotential) is created in the crystal by applying a stress. Owing to the simultaneous possession of piezoelectricity and semiconductor properties, the piezopotential created in the crystal has a strong effect on the carrier transport at the interface/junction. Piezotronics is about the devices fabricated using the piezopotential as a "gate" voltage to tune/control charge carrier transport at a contact or junction. The piezo-phototronic effect is to use the piezopotential to control the carrier generation, transport, separation and/or recombination for improving the performance of optoelectronic devices, such as photon detector, solar cell and LED. This manuscript reviews the updated progress in the two new fields. A perspective is given about their potential applications in sensors, human-silicon technology interfacing, MEMS, nanorobotics and energy sciences. Piezotronics is about devices fabricated using the piezopotential as a "gate" voltage to tune/control charge carrier transport at a contact or junction. The piezo-phototronic effect is to use the piezopotential to control the carrier generation, transport, separation and/or recombination for improving the performance of optoelectronic devices, such as photon detectors, solar cells and LEDs. This manuscript reviews progress in these two new fields. A perspective is given about their potential applications in sensors, human-silicon technology interfacing, MEMS, nanorobotics, and energy sciences. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Merrill A.H.,Georgia Institute of Technology
Chemical Reviews

There are several nomenclature systems for glycosphingolipids, and many compounds are still referred to by their historically assigned names. Some of the breakthroughs in understanding the functions of sphingolipids, especially with respect to cell signaling, have come from having the capacity to measure more than one bioactive subspecies so the correct signaling pathways can be sorted out, especially when the metabolites have opposite effects, such as ceramide versus S1P. The relationships are being explored as a way for cancer detection and targeting using Shiga toxin. The story for iGb3 is less clear because although it stimulates NKT cells and has been hypothesized to be a natural modulator of them, recent studies have found that the human iGb3 synthase gene contains several mutations that render its product nonfunctional. A number of physiological factors have also been found to modulate DES. Source

Sherrill C.D.,Georgia Institute of Technology
Accounts of Chemical Research

Fundamental features of biomolecules, such as their structure, solvation, and crystal packing and even the docking of drugs, rely on noncovalent interactions. Theory can help elucidate the nature of these interactions, and energy component analysis reveals the contributions from the various intermolecular forces: electrostatics, London dispersion terms, induction (polarization), and short-range exchange-repulsion. Symmetry-adapted perturbation theory (SAPT) provides one method for this type of analysis.In this Account, we show several examples of how SAPT pro-vides insight into the nature of noncovalent π-interactions. In cation-π interactions, the cation strongly polarizes electrons in π-orbitals, leading to substantially attractive induction terms. This polarization is so important that a cation and a benzene attract each other when placed in the same plane, even though a consideration of the electrostatic interactions alone would suggest otherwise. SAPT analysis can also support an understanding of substituent effects in π-π interactions. Trends in face-to-face sandwich benzene dimers cannot be understood solely in terms of electrostatic effects, especially for multiply substituted dimers, but SAPT analysis demonstrates the importance of London dispersion forces. Moreover, detailed SAPT studies also reveal the critical importance of charge penetration effects in π-stacking interactions. These effects arise in cases with substantial orbital overlap, such as in π-stacking in DNA or in crystal structures of π-conjugated materials. These charge penetration effects lead to attractive electrostatic terms where a simpler analysis based on atom-centered charges, electrostatic potential plots, or even distributed multipole analysis would incorrectly predict repulsive electrostatics. SAPT analysis of sandwich benzene, benzene-pyridine, and pyridine dimers indicates that dipole/induced-dipole terms present in benzene-pyridine but not in benzene dimer are relatively unimportant. In general, a nitrogen heteroatom contracts the electron density, reducing the magnitude of both the London dispersion and the exchange-repulsion terms, but with an overall net increase in attraction.Finally, using recent advances in SAPT algorithms, researchers can now perform SAPT computations on systems with 200 atoms or more. We discuss a recent study of the intercalation complex of proflavine with a trinucleotide duplex of DNA. Here, London dispersion forces are the strongest contributors to binding, as is typical for π-π interactions. However, the electrostatic terms are larger than usual on a fractional basis, which likely results from the positive charge on the intercalator and its location between two electron-rich base pairs. These cation-π interactions also increase the induction term beyond those of typical noncovalent π-interactions. © 2012 American Chemical Society. Source

Xu S.,Georgia Institute of Technology
Nature communications

Harvesting energy from irregular/random mechanical actions in variable and uncontrollable environments is an effective approach for powering wireless mobile electronics to meet a wide range of applications in our daily life. Piezoelectric nanowires are robust and can be stimulated by tiny physical motions/disturbances over a range of frequencies. Here, we demonstrate the first chemical epitaxial growth of PbZr(x)Ti(1-x)O(3) (PZT) nanowire arrays at 230 °C and their application as high-output energy converters. The nanogenerators fabricated using a single array of PZT nanowires produce a peak output voltage of ~0.7 V, current density of 4 μA cm(-2) and an average power density of 2.8 mW cm(-3). The alternating current output of the nanogenerator is rectified, and the harvested energy is stored and later used to light up a commercial laser diode. This work demonstrates the feasibility of using nanogenerators for powering mobile and even personal microelectronics. Source

Goldman D.I.,Georgia Institute of Technology
Reviews of Modern Physics

Biological locomotion, movement within environments through self-deformation, encompasses a range of time and length scales in an organism. These include the electrophysiology of the nervous system, the dynamics of muscle activation, the mechanics of the skeletal system, and the interaction mechanics of such structures within natural environments like water, air, sand, and mud. Unlike the many studies of cellular and molecular scale biophysical processes, movement of entire organisms (like flies, lizards, and snakes) is less explored. Further, while movement in fluids like air and water is also well studied, little is known in detail of the mechanics that organisms use to move on and within flowable terrestrial materials such as granular media, ensembles of small particles that collectively display solid, fluid, and gaslike behaviors. This Colloquium reviews recent progress to understand principles of biomechanics and granular physics responsible for locomotion of the sandfish, a small desert-dwelling lizard that "swims" within sand using undulation of its body. Kinematic and muscle activity measurements of sand swimming using high speed x-ray imaging and electromyography are discussed. This locomotion problem poses an interesting challenge: namely, that equations that govern the interaction of the lizard with its environment do not yet exist. Therefore, complementary modeling approaches are also described: resistive force theory for granular media, multiparticle simulation modeling, and robotic physical modeling. The models reproduce biomechanical and neuromechanical aspects of sand swimming and give insight into how effective locomotion arises from the coupling of the body movement and flow of the granular medium. The argument is given that biophysical study of movement provides exciting opportunities to investigate emergent aspects of living systems that might not depend sensitively on biological details. © 2014 American Physical Society. Source

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