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Articles 481 - 510 of 541

Full-Text Articles in Nanoscience and Nanotechnology

Imaging Gold Nanorods By Plasmon-Resonance-Enhanced Four Wave Mixing, Yookyung Jung, Hongtao Chen, Ling Tong, Ji-Xin Cheng Feb 2009

Imaging Gold Nanorods By Plasmon-Resonance-Enhanced Four Wave Mixing, Yookyung Jung, Hongtao Chen, Ling Tong, Ji-Xin Cheng

Other Nanotechnology Publications

The current work investigates the four-wave mixing (FWM) signal from gold nanorods (NRs) using two synchronized lasers and its potential applications in bioimaging. Using the lightning rod model, we show that the strongest FWM occurs when the pump laser wavelength is tuned to be resonant with the longitudinal plasmon resonance wavelength of NR. The calculation is experimentally demonstrated by comparing the intensities of FWM from NRs with different plasmon resonance wavelengths. The FWM signal is further found to be enhanced by aggregation of NRs and is strongly dependent on pulse width. The FWM intensity from NRs is similar to 39 …

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Influence Of Dimensionality On Thermoelectric Device Performance, Raseong Kim, Supriyo Datta, Mark S. Lundstrom Feb 2009

Influence Of Dimensionality On Thermoelectric Device Performance, Raseong Kim, Supriyo Datta, Mark S. Lundstrom

Birck and NCN Publications

The role of dimensionality on the electronic performance of thermoelectric devices is clarified using the Landauer formalism, which shows that the thermoelectric coefficients are related to the transmission, T(E), and how the conducting channels, M(E), are distributed in energy. The Landauer formalism applies from the ballistic to diffusive limits and provides a clear way to compare performance in different dimensions. It also provides a physical interpretation of the "transport distribution," a quantity that arises in the Boltzmann transport equation approach. Quantitative comparison of thermoelectric coefficients in one, two, and three dimensions shows that the channels are utilized more effectively in …

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Valley Degeneracies In (111) Silicon Quantum Wells, Neerav Kharche, Seongmin Kim, Timothy B. Boykin, Gerhard Klimeck Jan 2009

Valley Degeneracies In (111) Silicon Quantum Wells, Neerav Kharche, Seongmin Kim, Timothy B. Boykin, Gerhard Klimeck

Birck and NCN Publications

(111) silicon quantum wells have been studied extensively, yet no convincing explanation exists for the experimentally observed breaking of sixfold valley degeneracy into two- and fourfold degeneracies. Here, systematic sp(3)d(5)s(*) tight-binding and effective mass calculations are presented to show that a typical miscut modulates the energy levels, which leads to breaking of sixfold valley degeneracy into two lower and four raised valleys. An effective mass based valley-projection model is used to determine the directions of valley minima in tight-binding calculations of large supercells. Tight-binding calculations are in better agreement with experiments compared to effective mass calculations.

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Spin-Orbit Splittings In Si/Sige Quantum Wells: From Ideal Si Membranes To Realistic Hterostructures, M. Prada, G. Klimeck, R. Joynt Jan 2009

Spin-Orbit Splittings In Si/Sige Quantum Wells: From Ideal Si Membranes To Realistic Hterostructures, M. Prada, G. Klimeck, R. Joynt

Birck and NCN Publications

We present a calculation of the wavevector-dependent subband level splitting from spin-orbit coupling in Si/SiGe quantum wells. We first use the effective-mass approach, where the splittings are parameterized by separating contributions from the Rashba and Dresselhaus terms. We then determine the inversion asymmetry parameters by fitting tight-binding numerical results obtained using the quantitative nanoelectronic modeling tool, NEMO-3D. We describe the relevant coefficients as a function of applied electric field and well width in our numerical simulations. Symmetry arguments can also predict the behavior, and an extensive analysis is also presented in this work. Using vast computational resources, we treat alloy …

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Nano-Switch For Study Of Gold Contact Behavior, Adam Fruehling, Shijun Xiao, Minghao Qi, Kaushik Roy, Dimitrios Peroulis Jan 2009

Nano-Switch For Study Of Gold Contact Behavior, Adam Fruehling, Shijun Xiao, Minghao Qi, Kaushik Roy, Dimitrios Peroulis

Birck and NCN Publications

In this paper we present the fabrication and characterization of a new NEMS DC switch as a vehicle to characterize Au-to-Au contacts at nano-scale. The switch consists of a 1050-nm long, 200-nm wide and 50-nm thick cantilever gold beam. The measured on-state resistance values range from 83 Omega to 640 Omega and the actuation voltages from 4 V to 22 V. All measurements are conducted at a current of 1 mu A and the obtained values are in good qualitative agreement with traditional elastic-plastic contact models. The calculated switching time is 55 ns. Characterization of contacts at nano-scale will be …

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Stabilizing Nanostructured Materials By Coherent Nanotwins And Their Grain Boundary Triple Junction Drag, C Saldana, T G. Murthy, M R. Shankar, E A. Stach, S Chandrasekar Jan 2009

Stabilizing Nanostructured Materials By Coherent Nanotwins And Their Grain Boundary Triple Junction Drag, C Saldana, T G. Murthy, M R. Shankar, E A. Stach, S Chandrasekar

Birck and NCN Publications

The role of nanotwin lamellae in enhancing thermal stability of nanostructured materials is examined. Nanostructured copper with varying densities of twins was generated by controlling the deformation strain rate during severe plastic deformation at cryogenic temperatures. While the nanostructured materials produced under cryogenic conditions are characteristically unstable even at room temperatures, their stability is markedly improved when a dense dispersion of nanotwins is introduced. Observations of the role of nanotwins in pinning grain and subgrain structures suggest an interfacial engineering approach to enhancing the stability of nanostructured alloys.

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Identification Of Multiple Oscillation States Of Carbon Nanotube Tipped Cantilevers Interacting With Surfaces In Dynamic Atomic Force Microscopy, Mark Strus, Arvind Raman Jan 2009

Identification Of Multiple Oscillation States Of Carbon Nanotube Tipped Cantilevers Interacting With Surfaces In Dynamic Atomic Force Microscopy, Mark Strus, Arvind Raman

Birck and NCN Publications

Carbon nanotubes (CNTs) have gained increased interest in dynamic atomic force microscopy (dAFM) as sharp, flexible, conducting, nonreactive tips for high-resolution imaging, oxidation lithography, and electrostatic force microscopy. By means of theory and experiments we lay out a map of several distinct tapping mode AFM oscillation states for CNT tipped AFM cantilevers: namely, noncontact attractive regime oscillation, intermittent contact with CNT slipping or pinning, or permanent contact with the CNT in point or line contact with the surface while the cantilever oscillates with large amplitude. Each state represents fundamentally different origins of CNT-surface interactions, CNT tip-substrate dissipation, and phase contrast …

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Orbital Start Effect And Quantum Confinement Transition Of Donors In Silicon, Rajib Rahman, G. P. Lansbergen, Seung H. Park, J. Verdujin, Gerhard Klimeck, S. Rogge, Lloyd C. L. Hollenberg Jan 2009

Orbital Start Effect And Quantum Confinement Transition Of Donors In Silicon, Rajib Rahman, G. P. Lansbergen, Seung H. Park, J. Verdujin, Gerhard Klimeck, S. Rogge, Lloyd C. L. Hollenberg

Birck and NCN Publications

Adiabatic shuttling of single impurity bound electrons to gate-induced surface states in semiconductors has attracted much attention in recent times, mostly in the context of solid-state quantum computer architecture. A recent transport spectroscopy experiment for the first time was able to probe the Stark shifted spectrum of a single donor in silicon buried close to a gate. Here, we present the full theoretical model involving large-scale quantum mechanical simulations that was used to compute the Stark shifted donor states in order to interpret the experimental data. Use of atomistic tight-binding technique on a domain of over a million atoms helped …

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Atomistic Full-Band Simulations Of Si Nanowire Transistors: Effects Of Electron-Phonon Scattering, Mathieu Luisier, Gerhard Klimeck Jan 2009

Atomistic Full-Band Simulations Of Si Nanowire Transistors: Effects Of Electron-Phonon Scattering, Mathieu Luisier, Gerhard Klimeck

Birck and NCN Publications

An atomistic full-band quantum transport simulator has been developed to study three-dimensional Si nanowire field-effect transistors (FETs) in the presence of electron-phonon scattering. The Non-equilibrium Green's Function (NEGF) formalism is solved in a nearest-neighbor sp(3)d(5)s* tight-binding basis. The scattering self-energies are derived in the self-consistent Born approximation to inelastically couple the full electron and phonon energy spectra. The band dispersion and the eigenmodes of the confined phonons are calculated using a dynamical matrix that includes the bond and angle deformations of the nanowires. The optimization of the numerical algorithms and the parallelization of the NEGF scheme enable the investigation of …

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A Stochastic Collocation Approach To Bayesian Inference In Inverse Problems, Youssef Marzouk, Dongbin Xiu Jan 2009

A Stochastic Collocation Approach To Bayesian Inference In Inverse Problems, Youssef Marzouk, Dongbin Xiu

PRISM: NNSA Center for Prediction of Reliability, Integrity and Survivability of Microsystems

We present an efficient numerical strategy for the Bayesian solution of inverse problems. Stochastic collocation methods, based on generalized polynomial chaos (gPC), are used to construct a polynomial approximation of the forward solution over the support of the prior distribution. This approximation then defines a surrogate posterior probability density that can be evaluated repeatedly at minimal computational cost. The ability to simulate a large number of samples from the posterior distribution results in very accurate estimates of the inverse solution and its associated uncertainty. Combined with high accuracy of the gPC-based forward solver, the new algorithm can provide great efficiency …

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Coarse Grain Modeling Of Spall Failure In Molecular Crystals: Role Of Intra-Molecular Degrees Of Freedom, Karen Lynch, Alexander Thompson, Alejandro Strachan Jan 2009

Coarse Grain Modeling Of Spall Failure In Molecular Crystals: Role Of Intra-Molecular Degrees Of Freedom, Karen Lynch, Alexander Thompson, Alejandro Strachan

PRISM: NNSA Center for Prediction of Reliability, Integrity and Survivability of Microsystems

We use a recently developed thermodynamically accurate mesodynamical method (Strachan and Holian 2005 Phys. Rev. Lett. 94 014301) where groups of atoms are represented by mesoparticles to characterize the shock compression and dynamical failure (spall) of a model molecular crystal. We characterize how the temperature rise caused by the shockwave depends on the specific heat of the degrees of freedom (DoFs) internal to the mesoparticles (Cint) and the strength of the coupling between the internal DoFs and the mesoparticles. We find that the temperature of the shocked material decreases with increasing Cint and decreasing coupling and quantify these effects. Our …

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A Generalized Polynomial Chaos Based Ensemble Kalman Filter, Jia Li, Dongbin Xiu Jan 2009

A Generalized Polynomial Chaos Based Ensemble Kalman Filter, Jia Li, Dongbin Xiu

PRISM: NNSA Center for Prediction of Reliability, Integrity and Survivability of Microsystems

As one of the most adopted sequential data assimilation methods in many areas, especially those involving complex nonlinear dynamics, the ensemble Kalman filter (EnKF) has been under extensive investigation regarding its properties and efficiency. Compared to other variants of the Kalman filter (KF), EnKF is straightforward to implement, as it employs random ensembles to represent solution states. This, however, introduces sampling errors that affect the accuracy of EnKF in a negative manner. Though sampling errors can be easily reduced by using a large number of samples, in practice this is undesirable as each ensemble member is a solution of the …

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Advancing Nanoelectronic Device Modeling Through Peta-Scale Computing And Deployment On Nanohub, Benjamin Haley, Sunhee Lee, Mathieu Luisier, Hoon Ryu, Faisal Saied, Steven Clark, Hansang Bae, Gerhard Klimeck Jan 2009

Advancing Nanoelectronic Device Modeling Through Peta-Scale Computing And Deployment On Nanohub, Benjamin Haley, Sunhee Lee, Mathieu Luisier, Hoon Ryu, Faisal Saied, Steven Clark, Hansang Bae, Gerhard Klimeck

Birck and NCN Publications

Recent improvements to existing HPC codes NEMO 3-D and OMEN, combined with access to peta-scale computing resources, have enabled realistic device engineering simulations that were previously infeasible. NEMO 3-D can now simulate 1 billion atom systems, and, using 3D spatial decomposition, scale to 32768 cores. Simulation time for the band structure of an experimental P doped Si quantum computing device fell from 40 minutes to I minute. OMEN can perform fully quantum mechanical transport calculations for real-word UTB FETs on 147,456 cores in roughly 5 minutes. Both of these tools power simulation engines on the nanoHUB, giving the community access …

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Parallel Reactive Molecular Dynamics: Numerical Methods And Algorithmic Techniques, Hasan Metin Aktulga, Joseph C. Fogarty, Sagar A. Pandit, Ananth Y. Grama Jan 2009

Parallel Reactive Molecular Dynamics: Numerical Methods And Algorithmic Techniques, Hasan Metin Aktulga, Joseph C. Fogarty, Sagar A. Pandit, Ananth Y. Grama

PRISM: NNSA Center for Prediction of Reliability, Integrity and Survivability of Microsystems

No abstract provided.

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Gold Nanorods As Contrast Agents For Biological Imaging: Optical Properties, Surface Conjugation And Photothermal Effects, Ling Tong, Qingshan Wei, Alexander Wei, Ji-Xin Cheng Jan 2009

Gold Nanorods As Contrast Agents For Biological Imaging: Optical Properties, Surface Conjugation And Photothermal Effects, Ling Tong, Qingshan Wei, Alexander Wei, Ji-Xin Cheng

Other Nanotechnology Publications

Gold nanorods (NRs) have plasmon-resonant absorption and scattering in the near-infrared (NIR) region, making them attractive probes for in vitro and in vivo imaging. In the cellular environment, NRs can provide scattering contrast for darkfield microscopy, or emit a strong two-photon luminescence due to plasmon-enhanced two-photon absorption. NRs have also been employed in biomedical imaging modalities such as optical coherence tomography or photoacoustic tomography. Careful control over surface chemistry enhances the capacity of NRs as biological imaging agents by enabling cell-specific targeting, and by increasing their dispersion stability and circulation lifetimes. NRs can also efficiently convert optical energy into heat, …

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Nanoantenna Array-Induced Fluorescence Enhancement And Reduced Lifetimes, Reuben M. Bakker, V. P. Drachev, Zhengtong Liu, Hsiao-Kuan Yuan, Rasmus H. Pedersen, Alexandra Boltasseva, Jiji Chen, Joseph Irudayaraj, Alexander V. Kildishev, V. M. Shalaev Dec 2008

Nanoantenna Array-Induced Fluorescence Enhancement And Reduced Lifetimes, Reuben M. Bakker, V. P. Drachev, Zhengtong Liu, Hsiao-Kuan Yuan, Rasmus H. Pedersen, Alexandra Boltasseva, Jiji Chen, Joseph Irudayaraj, Alexander V. Kildishev, V. M. Shalaev

Birck and NCN Publications

Enhanced fluorescence is observed from dye molecules interacting with optical nanoantenna arrays. Elliptical gold dimers form individual nanoantennae with tunable plasmon resonances depending upon the geometry of the two particles and the size of the gap between them. A fluorescent dye, Rhodamine 800, is uniformly embedded in a dielectric host that coats the nanoantennae. The nanoantennae act to enhance the dye absorption. In turn, emission from the dye drives the plasmon resonance of the antennae; the nanoantennae act to enhance the fluorescence signal and change the angular distribution of emission. These effects depend upon the overlap of the plasmon resonance …

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Transport-Based Dopant Metrology In Advanced Finfets, Gabriel P. Lansbergen, Rajib Rahman, Cameron J. Wellard, Jaap Caro, Nadine Collaert, Serge Biesemans, Gerhard Klimeck, Lloyd C. L. Hollenberg, Sven Rogge Dec 2008

Transport-Based Dopant Metrology In Advanced Finfets, Gabriel P. Lansbergen, Rajib Rahman, Cameron J. Wellard, Jaap Caro, Nadine Collaert, Serge Biesemans, Gerhard Klimeck, Lloyd C. L. Hollenberg, Sven Rogge

Other Nanotechnology Publications

Ultra-scaled FinFET transistors bear unique fingerprint-like device-to-device differences attributed to random single impurities. Through correlation of experimental data with multimillion atom simulations in NEMO 3-D, we can identify the impurity’s chemical species and determine their concentration, local electric field and depth below the Si/SiO2 interface. The ability to model the excited states rather than just the ground states is the critical need. We therefore demonstrate a new approach to atomistic impurity metrology and confirm the assumption of tunneling through individual impurity quantum states.

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Atomic-Layer-Deposited Al2o3/Gaas Metal-Oxide-Semiconductor Field-Effect Transistor On Si Substrate Using Aspect Ratio Trapping Technique, Y Q. Wu, M Xu, P. D. Ye, Z Cheng, J Li, J Park, J Hydrick, J Bai, M Carroll, J G. Fiorenza, A Lochtefeld Dec 2008

Atomic-Layer-Deposited Al2o3/Gaas Metal-Oxide-Semiconductor Field-Effect Transistor On Si Substrate Using Aspect Ratio Trapping Technique, Y Q. Wu, M Xu, P. D. Ye, Z Cheng, J Li, J Park, J Hydrick, J Bai, M Carroll, J G. Fiorenza, A Lochtefeld

Birck and NCN Publications

High quality GaAs epilayers grown by metal-organic chemical vapor deposition are demonstrated on a SiO2-patterned silicon substrate using aspect ratio trapping technique, whereby threading dislocations from lattice mismatch are largely reduced via trapping in SiO2 trenches during growth. A depletion-mode metal-oxide-semiconductor field-effect transistor (MOSFET) is demonstrated on a n-doped GaAs channel with atomic-layer deposited Al2O3 as the gate oxide. The 10 mu m gate length transistor has a maximum drain current of 88 mA/mm and a transconductance of 19 mS/mm. The surface mobility estimated from the accumulation drain current has a peak value of similar to 500 cm(2)/Vs, which is …

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Full-Band And Atomisic Simulation Of Realistic 40 Nm Inas Hemt, Mathieu Luisier, Neophytos Neophytou, Neerav Kharche, Gerhard Klimeck Dec 2008

Full-Band And Atomisic Simulation Of Realistic 40 Nm Inas Hemt, Mathieu Luisier, Neophytos Neophytou, Neerav Kharche, Gerhard Klimeck

Other Nanotechnology Publications

A realistic 40 nm InAs high electron mobility transistor is studied using a two-dimensional, full-band, and atomistic Schr¨odinger-Poisson solver based on the sp3d5s∗ tightbinding model. Bandstructure non-parabolicity effects, strain, alloy disorder in the InGaAs and InAlAs barriers, as well as band-to-band tunneling in the transistor OFF-state are automatically included through the full-band atomistic model. The source and drain contact extensions are taken into account a posteriori by adding two series resistances to the device channel. The simulated current characteristics are compared to measured data and show a good quantitative agreement.

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From Nemo1d And Nemo3d To Omen: Moving Towards Atomistic 3-D Quantum Transport In Nano-Scale Semiconductors, Gerhard Klimeck, Mathieu Luisier Dec 2008

From Nemo1d And Nemo3d To Omen: Moving Towards Atomistic 3-D Quantum Transport In Nano-Scale Semiconductors, Gerhard Klimeck, Mathieu Luisier

Other Nanotechnology Publications

Lessons learned in 15 years of NEMO development starting from quantitative and predictive resonant tunneling diode (RTD) to multi-million atom electronic structure modeling and the path for OMEN are laid out. The recent OMEN capabilities enable realistically large 3D atomistic nano-scale device simulation.

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Optical Hyperspace For Plasmons: Dyakonov States In Metamaterials, Zubin Jacob, Evgenii E. Narimanov Dec 2008

Optical Hyperspace For Plasmons: Dyakonov States In Metamaterials, Zubin Jacob, Evgenii E. Narimanov

Birck and NCN Publications

We show that the subdiffraction imaging behavior observed in the magnifying superlens experiment, [Smolyaninov , Science 317, 1699 (2007)] is due to the hyperbolic dispersion of Dyakonov plasmons supported by the device. These states which are a special case of Dyakonov surface waves [Dyakonov, Sov. Phys. JETP 67, 714 (1988)] exist at the interface of a metal and an anisotropic dielectric giving rise to plasmon beams on resonance. Furthermore, we describe how the unique properties of metamaterial Dyakonov plasmons can be tailored for plasmonic devices.

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Hydrodynamic Loading Of Microcantilevers Oscillating Near Rigid Walls, Ryan C. Tung, Jana Anirban, Arvind Raman Dec 2008

Hydrodynamic Loading Of Microcantilevers Oscillating Near Rigid Walls, Ryan C. Tung, Jana Anirban, Arvind Raman

Birck and NCN Publications

The vibrations of microcantilevers in atomic force microscopes (AFMs) or radio frequency (RF) switches are strongly influenced by the viscous hydrodynamics of the surrounding fluid in the vicinity of a rigid wall. While prior efforts to model this hydrodynamic loading have focused on squeeze film damping effects at high Knudsen and squeeze numbers, the regimes of low Knudsen and squeeze numbers are also very important for which squeeze film models need to be discarded in favor of unsteady Stokes hydrodynamics. We extend the work of Green and Sader [Phys Fluids 17, 073102 (2005); J. Appl. Phys. 98, 114913 (2005)] and …

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Solutions In Folded Geometries, And Associated Cloaking Due To Anomalous Resonance, Graeme W. Milton, Nicolae-Alexandru P. Nicorovici, Ross C. Mcphedran, Kirill Cherednichenko, Zubin Jacob Nov 2008

Solutions In Folded Geometries, And Associated Cloaking Due To Anomalous Resonance, Graeme W. Milton, Nicolae-Alexandru P. Nicorovici, Ross C. Mcphedran, Kirill Cherednichenko, Zubin Jacob

Birck and NCN Publications

Solutions for the fields in a coated cylinder where the core radius is bigger than the shell radius are seemingly unphysical, but can be given a physical meaning if one transforms to an equivalent problem by unfolding the geometry. In particular, the unfolded material can act as an impedance matched hyperlens, and as the loss in the lens goes to zero finite collections of polarizable line dipoles lying within a critical region surrounding the hyperlens are shown to be cloaked having vanishingly small dipole moments. This cloaking, which occurs both in the folded geometry and the equivalent unfolded one, is …

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Transformation Optics: Approaching Broadband Electromagnetic Cloaking, Alexander V. Kildishev, W Cai, U K. Chettiar, V. M. Shalaev Nov 2008

Transformation Optics: Approaching Broadband Electromagnetic Cloaking, Alexander V. Kildishev, W Cai, U K. Chettiar, V. M. Shalaev

Birck and NCN Publications

An approach to broadband cloaking of light waves is analysed for a simplified case of a scaling transformation for a general cylindrical coordinate system. The proposed approach requires metamaterials with specifically engineered dispersion. The restriction on the signs of gradients in the dispersion dependencies of the dielectric permittivity and the magnetic permeability for different operational wavelengths is revealed and is shown to cause difficulties unless additional gain-assisted compensation for losses or electromagnetically induced transparency is introduced in the cloaking system.

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Toward Nanowire Electronics, Joerg Appenzeller, Joachim Knoch, Mikael Bjoerk, Heike Riel, Heinz Schmid, Walter Riess Nov 2008

Toward Nanowire Electronics, Joerg Appenzeller, Joachim Knoch, Mikael Bjoerk, Heike Riel, Heinz Schmid, Walter Riess

Other Nanotechnology Publications

This paper discusses the electronic transport properties of nanowire field-effect transistors (NW-FETs). Four different device concepts are studied in detail: Schottky-barrier NW-FETs with metallic source and drain contacts, conventional-type NW-FETs with doped NW segments as source and drain electrodes, and, finally, two new concepts that enable steep turn-on characteristics, namely, NW impact ionization FETs and tunnel NW-FETs. As it turns out, NW-FETs are, to a large extent, determined by the device geometry, the dimensionality of the electronic transport, and the way of making contacts to the NW. Analytical as well as simulation results are compared with experimental data to explain …

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Structures And Energetics Of Silicon Nanotubes From Molecular Dynamics And Density Functional Theory, Amritanshu Palaria, Gerhard Klimeck, Alejandro Strachan Nov 2008

Structures And Energetics Of Silicon Nanotubes From Molecular Dynamics And Density Functional Theory, Amritanshu Palaria, Gerhard Klimeck, Alejandro Strachan

PRISM: NNSA Center for Prediction of Reliability, Integrity and Survivability of Microsystems

We use molecular dynamics with a first-principles-based force field and density functional theory to predict the atomic structure, energetics, and elastic properties of Si nanotubes. We find various low-energy and low-symmetry hollow structures with external diameters of about 1 nm. These are the most stable structures in this small-diameter regime reported so far and exhibit properties very different from the bulk. While the cohesive energies of the four most stable nanotubes reported here are similar (from 0.638 to 0.697 eV above bulk Si), they have disparate Young's moduli (from 72 to 123 GPa).

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Bright-Field Analysis Of Phi29 Dna Packaging Motor Using A Magnetomechanical System, Chun-Li Chang, Hui Zhang, Dan Shu, Peixuan Guo, Cagri A. Savran Oct 2008

Bright-Field Analysis Of Phi29 Dna Packaging Motor Using A Magnetomechanical System, Chun-Li Chang, Hui Zhang, Dan Shu, Peixuan Guo, Cagri A. Savran

Birck and NCN Publications

We report a simple and robust magnetomechanical system for direct visual observation of the DNA packaging behavior of the bacteriophage phi29 in real time. The system comprises a micron-sized magnetic bead attached to the free end of the viral DNA, a magnet and a bright-field microscope. We show that the phi29 DNA packaging activity can be observed and dynamically analyzed at the single molecular level in bright field with a relatively simple system. With this system we also visually demonstrate the phi29 motor transporting a cargo 10 000 times the viral size.

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A Parallel Spectral Element Method For Dynamic Three-Dimensional Nonlinear Elasticity Problems, S. Dong, Z. Yosibash Sep 2008

A Parallel Spectral Element Method For Dynamic Three-Dimensional Nonlinear Elasticity Problems, S. Dong, Z. Yosibash

PRISM: NNSA Center for Prediction of Reliability, Integrity and Survivability of Microsystems

We present a high-order method employing Jacobi polynomial-based shape functions, as an alternative to the typical Legendre polynomial-based shape functions in solid mechanics, for solving dynamic three-dimensional geometrically nonlinear elasticity problems. We demonstrate that the method has an exponential convergence rate spatially and a second-order accuracy temporally for the four classes of problems of linear/geometrically nonlinear elastostatics/elastodynamics. The method is parallelized through domain decomposition and message passing interface (MPI), and is scaled to over 2000 processors with high parallel performance.

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Level Spectrum Of Single Gated As Donors, Gabriel P. Lansbergen, Rajib Rahman, J. Caro, N. Collaert, S. Biesemans, Gerhard Klimeck, S. Rogge, L.C. L. Hollenberg Jul 2008

Level Spectrum Of Single Gated As Donors, Gabriel P. Lansbergen, Rajib Rahman, J. Caro, N. Collaert, S. Biesemans, Gerhard Klimeck, S. Rogge, L.C. L. Hollenberg

Other Nanotechnology Publications

We study the electrical transport through single As donors incorporated in the channel of a FinFET, i.e. a donor in a three-terminal geometry. By means of spectroscopic measurements in conjuction with a NEMO-3D model, we can identify the excited states and associate them with either the donors Coulomb potential, a triangular well at the interface or a hybridized combination of the two. The correspondence between the transport measurements, the theoretical model and the local environment provides an atomic understanding of actual gated donors in a nanostructure.

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Release Of Hydrophobic Molecules From Polymer Micelles Into Cell Membranes Revealed By Forster Resonance Energy Transfer Imaging, Hongtao Chen, Sungwon Kim, Shuyi Wang, Kinam Park, Ji-Xin Cheng May 2008

Release Of Hydrophobic Molecules From Polymer Micelles Into Cell Membranes Revealed By Forster Resonance Energy Transfer Imaging, Hongtao Chen, Sungwon Kim, Shuyi Wang, Kinam Park, Ji-Xin Cheng

Other Nanotechnology Publications

it is generally assumed that polymeric micelles, upon administration into the blood stream, carry drug molecules until they are taken up into cells followed by intracellular release. The current work revisits this conventional wisdom. The study using dual-labeled micelles containing fluorescently labeled copolymers and hydrophobic fluorescent probes entrapped in the polymeric micelle core showed that cellular uptake of hydrophobic probes was much faster than that of labeled copolymers. This result implies that the hydrophobic probes in the core are released from micelles in the extracellular space. Forster resonance energy transfer (FRET) imaging and spectroscopy were used to monitor this process …

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