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Articles 3241 - 3270 of 3535

Full-Text Articles in Nanoscience and Nanotechnology

Ballisticity Of Nanotube Field-Effect Transistors: Role Of Phonon Energy And Gate Bias, Siyuranga O. Koswatta, Sayed Hasan, Mark S. Lundstrom, M. P. Anantram, Dmitri E. Nikonov Jul 2006

Ballisticity Of Nanotube Field-Effect Transistors: Role Of Phonon Energy And Gate Bias, Siyuranga O. Koswatta, Sayed Hasan, Mark S. Lundstrom, M. P. Anantram, Dmitri E. Nikonov

Other Nanotechnology Publications

We investigate the role of electron-phonon scattering and gate bias in degrading the drive current of nanotube field-effect transistors (FETs). Optical phonon scattering significantly decreases the drive current only when gate voltage is higher than a well-defined threshold. For comparable electron-phonon coupling, a lower phonon energy leads to a larger degradation of drive current. Thus in semiconductor nanowire FETs, the drive current will be more sensitive than in carbon nanotube FETs because of the smaller phonon energies in semiconductors. Acoustic phonons and other elastic scattering mechanisms are most detrimental to nanotube FETs irrespective of biasing conditions.

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Refractive Indices And Band-Gap Properties Of Rocksalt Mg XZn Sub>1-XO (0.68 ≤X≤1), RüDiger Schmidt-Grund, Anke Carstens, Bernd Rheinländer, Daniel Spemann, Holger Hochmut, Gregor Zimmermann, Michael Lorenz, Marius Grundmann, Craig M. Herzinger, Mathias Schubert Jun 2006

Refractive Indices And Band-Gap Properties Of Rocksalt Mg XZn Sub>1-XO (0.68 ≤X≤1), RüDiger Schmidt-Grund, Anke Carstens, Bernd Rheinländer, Daniel Spemann, Holger Hochmut, Gregor Zimmermann, Michael Lorenz, Marius Grundmann, Craig M. Herzinger, Mathias Schubert

Nebraska Center for Materials and Nanoscience: Faculty Publications

The room-temperature optical pseudo-dielectric-functions of single-phase, single-crystalline rocksalt-structure MgxZn1-xO with Mg-content x between 0.68 and 1 were determined in the photon energy range from 0.75 to 9.10 eV using spectroscopic ellipsometry. The refractive index determined in the spectral region below the fundamental absorption edge decreases with increasing Mg content. The pseudo-dielectric-functions reveal structures caused in critical points due to electronic band-to-band transitions and free exciton formation at the fundamental band-gap transition. Standard model dielectric function approaches were applied for line shape analysis. Upon increase of the bond ionicity with increasing Mg content the energies of …

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High-Resolution Thin-Film Device To Sense Texture By Touch, Ravi F. Saraf, Vivek Maheshwari Jun 2006

High-Resolution Thin-Film Device To Sense Texture By Touch, Ravi F. Saraf, Vivek Maheshwari

Papers in Nanotechnology

Touch (or tactile) sensors are gaining renewed interest as the level of sophistication in the application of minimum invasive surgery and humanoid robots increases. The spatial resolution of current large-area (greater than 1 cm2) tactile sensor lags by more than an order of magnitude compared with the human finger. By using metal and semi conducting nanoparticles, a 100-nm-thick, large-area thin-film device is self-assembled such that the change in current density through the film and the electroluminescent light intensity are linearly proportional to the local stress. A stress image is obtained by pressing a copper grid and a United …

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Infrared Optical Properties Of MgX-1Zn1-XO Thin Films (0≤X≤1): Long-Wavelength Optical Phonons And Dielectric Constants, C. Bundemann, A. Rahm, M. Lorenz, M. Grundmann, Mathias Schubert Jun 2006

Infrared Optical Properties Of MgX-1Zn1-XO Thin Films (0≤X≤1): Long-Wavelength Optical Phonons And Dielectric Constants, C. Bundemann, A. Rahm, M. Lorenz, M. Grundmann, Mathias Schubert

Nebraska Center for Materials and Nanoscience: Faculty Publications

Infrared spectroscopic ellipsometry in the spectral range from ω =360 cm-1 to ω =1500 cm-1 and Raman scattering spectroscopy are applied to study the long-wavelength optical phonon modes and dielectric constants of MgxZn1-xO thin films in the composition range 0≤x≤1. The samples were grown by pulsed laser deposition on sapphire substrates. X-ray diffraction measurements of the thin film samples reveal the hexagonal wurtzite crystal structure for x≤0.53 and the cubic rocksalt crystal structure for x≥0.67. A systematic variation of the phonon mode frequencies with Mg-mole fraction x is found …

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Electrochemical Preparation And Application Of Nanomaterials, Peng Liu, Ye-Xiang Tong, Qi-Qin Yang May 2006

Electrochemical Preparation And Application Of Nanomaterials, Peng Liu, Ye-Xiang Tong, Qi-Qin Yang

Journal of Electrochemistry

Nano materials and nano technology receive great attention all over the world.While electrochemistry has already achieved a great application in industry and it has proved that electrochemistry will play an important role in the field,such as energy source,new materials,life sciences,information sciences,environment and nano sciences.In this paper,the recent developments of electrochemical techniques for the preparing nano materials,application of nano materials in the areas of electrodeposition,batteries,electrocatalysis,sensors are introduced in brief.

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Electrochemical Studies On Electrocatalytic Activity Of AuCore PtShell Nanoparticles To Methanol Oxidation, Fang Bao, Jian-Lin Yao, Ren-Ao Gu May 2006

Electrochemical Studies On Electrocatalytic Activity Of AuCore PtShell Nanoparticles To Methanol Oxidation, Fang Bao, Jian-Lin Yao, Ren-Ao Gu

Journal of Electrochemistry

AucorePtshell nanoparticles with different thicknesses were prepared by using chemical reduction method,and characterized by ultraviolet-visible spectroscopy(UV-Vis),transmission electron microscopy(TEM) and cyclic voltammetry(CV).The electrocatalytic activity of AucorePtshell nanoparticles with the mean diameter of 70~80 nm to methanol oxidation was investigated by cyclic voltammetry in the acid solution.The results revealed that the prepared core-shell nanoparticles were covered by Pt shell and exhibited the similar optical property and electrocatalytic activity with the normal Pt surface.Moreover,the electrocatalytic activity increased with the electrochemical sweep in the certain potential range.It might be contributed by the special loose structure of Pt shell …

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United States Patent: Nano-Crystalline, Homo-Metallic, Protective Coatings, Fereydoon Namavar May 2006

United States Patent: Nano-Crystalline, Homo-Metallic, Protective Coatings, Fereydoon Namavar

Nebraska Center for Materials and Nanoscience: Faculty Publications

The present invention provides orthopedic prosthesis having at least one metallic component that includes a metallic substrate on which an integrally formed nano-crystalline coating is formed. The coating and the substrate have at least one metallic constituent in common having an average atomic concentration in the coating that differs from an average atomic concentration in the substrate by less than about 10 percent. Further, the nano-crystalline coatings includes crystalline grains with an average size in a range of about 1 to 999 nanometers, and more preferably in a range of about 10 to 200 nanometers. A transition region that exhibits …

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Desulfovibrio Desulfuricans G20 Tetraheme Cytochrome Structure At 1.5 A˚ And Cytochrome Interaction With Metal Complexes, Mrunalini Pattarkine, J J. Tanner, C A. Bottoms, Y H. Lee, Judy D. Wall May 2006

Desulfovibrio Desulfuricans G20 Tetraheme Cytochrome Structure At 1.5 A˚ And Cytochrome Interaction With Metal Complexes, Mrunalini Pattarkine, J J. Tanner, C A. Bottoms, Y H. Lee, Judy D. Wall

Faculty Works

The structure of the type I tetraheme cytochrome c3 from Desulfovibrio desulfuricans G20 was determined to 1.5 A˚ by X-ray crystallography. In addition to the oxidized form, the structure of the molybdate-bound form of the protein was determined from oxidized crystals soaked in sodium molybdate. Only small structural shifts were obtained with metal binding, consistent with the remarkable structural stability of this protein. In vitro experiments with pure cytochrome showed that molybdate could oxidize the reduced cytochrome, although not as rapidly as U(VI) present as uranyl acetate. Alterations in the overall conformation and thermostability of the metal-oxidized protein were investigated …

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Modeling And Representation Of Geometric Tolerances Information In Integrated Measurement Processes, Xiaoping Zhao, T. M. Kethara Pasupathy, Robert G. Wilhelm May 2006

Modeling And Representation Of Geometric Tolerances Information In Integrated Measurement Processes, Xiaoping Zhao, T. M. Kethara Pasupathy, Robert G. Wilhelm

Department of Mechanical and Materials Engineering: Faculty Publications

Modeling and representation of geometric tolerances information across an enterprise is viable due to the advances in Internet technologies and increasing integration requirements from industry. In Integrated Measurement Processes (IMP), geometric tolerances data model must support different models from several well-defined standards: including ASME Y14.5M-1994, STEP, DMIS, and others. In this paper, we propose a layered conformance level geometric tolerances representation model. This model uses the widely applied ASME Y14.5M-1994 as its foundation layer by abstracting most information from this standard. The additional geometric tolerances information defined by DMIS and STEP is incorporated into this model to form corresponding conformance …

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Magnetic Anisotropy And Anisotropic Ballistic Conductance Of Thin Magnetic Wires, Ildar F. Sabiryanov May 2006

Magnetic Anisotropy And Anisotropic Ballistic Conductance Of Thin Magnetic Wires, Ildar F. Sabiryanov

Nebraska Center for Materials and Nanoscience: Faculty Publications

The magnetocrystalline anisotropy of thin magnetic wires of iron and cobalt is quite different from the bulk phases. The spin moment of monatomic Fe wire may be as high as 3.4 μB, while the orbital moment as high as 0.5 μB. The magnetocrystalline anisotropy energy (MAE) was calculated for wires up to 0.6 nm in diameter starting from monatomic wire and adding consecutive shells for thicker wires. I observe that Fe wires exhibit the change sign with the stress applied along the wire. It means that easy axis may change from the direction along the wire …

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Effect Of Oxygen Vacancies On Interlayer Exchange Coupling In Fe/Mgo/Fe Tunnel Junctions, Mikhail Ye Zhuravlev, Julian P. Velev, A. V. Vedyayev, Evgeny Y. Tsymbal May 2006

Effect Of Oxygen Vacancies On Interlayer Exchange Coupling In Fe/Mgo/Fe Tunnel Junctions, Mikhail Ye Zhuravlev, Julian P. Velev, A. V. Vedyayev, Evgeny Y. Tsymbal

Nebraska Center for Materials and Nanoscience: Faculty Publications

We have investigated the interlayer exchange coupling (IEC) in Fe/MgO/Fe(0 0 1) tunnel junctions with and without oxygen vacancies in MgO, using model and density functional calculations. The model predicts that IEC changes sign from ferromagnetic to antiferromagnetic if a defect level matches the Fermi energy. Ab initio calculations show that for perfect junctions, IEC is ferromagnetic and decreases exponentially with MgO thickness. Oxygen vacancies placed in the middle of MgO make IEC antiferromagnetic for three monolayers (MLs) of MgO, but do not change the sign of IEC for five MLs. The latter fact is explained within the model, which …

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Highly Coercive Rapidly Solidified Sm–Co Alloys, Shampa Aich, V.K. Ravindran, Jeffrey E. Shield Apr 2006

Highly Coercive Rapidly Solidified Sm–Co Alloys, Shampa Aich, V.K. Ravindran, Jeffrey E. Shield

Nebraska Center for Materials and Nanoscience: Faculty Publications

Highly coercive (Hc up to 37 kOe at 300 K), high remanent permanent magnets have been achieved by rapid solidification of binary Sm–Co alloys and Sm–Co alloys modified with Nb and C. Rapidly solidified SmCox alloys with x ranging from 5 to 11.5 formed predominantly a solid solution TbCu7-type SmCo7 phase, although hcp Co was observed for x>7.3. A coercivity value of 10 kOe was observed for xx, as primary dendrites. Additions of 3 at. % Nb or 3 and 5 at. % C profoundly affected the coercivity values. Transmission electron microscopy (TEM) investigations revealed …

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Magnetic Behavior Of Rapidly Solidified Pr–Co Alloys With The Tbcu7-Type Structure, J. Kostogorova, Jeffrey E. Shield Apr 2006

Magnetic Behavior Of Rapidly Solidified Pr–Co Alloys With The Tbcu7-Type Structure, J. Kostogorova, Jeffrey E. Shield

Nebraska Center for Materials and Nanoscience: Faculty Publications

Rapid solidification has been utilized to produce a series of Pr–Co alloys between the Pr2Co17 and PrCo5 stoichiometries. In this system, PrCo5 has easy axis magnetization while Pr2Co17 has easy-plane magnetization. Alloys of the form (PrxCo1-x)94Ti3C3 with x ranging from 0.105 corresponding to the Pr2Co17 compound tox=0.167 corresponding to the PrCo5 compound were produced by melt spinning at a tangential wheel speed of 40 m/ s. The rapid solidification and alloying additions were found to suppress …

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Structural And Magnetic Properties Of Laves Compounds Dy1-XPrX(Fe0.35Co0.55B0.1)2 (0≤X≤1), W.J. Ren, D. Li, Yucheng Sui, W. Liu, X.G. Zhao, J.J. Liu, J. Li, Z.D. Zhang Apr 2006

Structural And Magnetic Properties Of Laves Compounds Dy1-XPrX(Fe0.35Co0.55B0.1)2 (0≤X≤1), W.J. Ren, D. Li, Yucheng Sui, W. Liu, X.G. Zhao, J.J. Liu, J. Li, Z.D. Zhang

Nebraska Center for Materials and Nanoscience: Faculty Publications

Dy1-xPrx(Fe0.35Co0.55B0.1)2 (0≤x≤1) Laves compounds with a cubic MgCu2-type structure were synthesized by arc melting and subsequent annealing. The lattice parameter of the Laves compounds linearly increases, while the Curie temperature Tc decreases with increasing Pr content. The saturation magnetization M5 at 5 K or 295 K for the Dy1-xPrx(Fe0.35Co0.55B0.1)2 alloys decreases to reach a minimum, then increases with increasing Pr content. The composition for magnetic moment compensation is about x …

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Multicomponent Patterning Of Nanocomposite Polymer And Nanoparticle Films Using Photolithography And Layer-By-Layer Self -Assembly, Javeed Shaikh Mohammed Apr 2006

Multicomponent Patterning Of Nanocomposite Polymer And Nanoparticle Films Using Photolithography And Layer-By-Layer Self -Assembly, Javeed Shaikh Mohammed

Doctoral Dissertations

In this dissertation, the fabrication, characterization, and application examples of 3D multicomponent nanocomposite micropatterns (MNMs) with precise spatial arrangements are described. The ability to produce such small-scale 3D structures with versatility in composition and structure is a new development based on the integration of nanoscale layer-by-layer (LbL) self-assembly and microscale photolithographic patterning, enabling construction of surfaces with microscale patterns that possess nanotopographies. The techniques used here are analogous to surface micromachining, except that the deposition materials are polymers, biological materials, and colloidal nanoparticles used to produce 3D MNMs. A key feature of the resulting 3D MNMs is that the physical …

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Interfaces, Volume 8, Issue 1 - Spring 2006 Apr 2006

Interfaces, Volume 8, Issue 1 - Spring 2006

INTERFACES: Newsletter of the Nebraska Center for Materials and Nanoscience

CONTENTS
From the Director
UNL Team Wins $3M DoD Grant
Recent Achievements of Center Researchers
Nanocomposite Permanent Magnets (by Jeff Shield)
NCMN Welcomes Mathias Schubert
Research Spotlight: Evgeny Tsymbal
Ion Beam Assisted Deposition at UNMC (by Fereydoon Namavar)
For the Ages - Book Projects at NCMN (by Ralph Skomski)

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Flexible Tools For Specifying Design Variation, Trichy Pasupathy, Xiaoping Zhao, Robert Wilhelm Apr 2006

Flexible Tools For Specifying Design Variation, Trichy Pasupathy, Xiaoping Zhao, Robert Wilhelm

Department of Mechanical and Materials Engineering: Faculty Publications

This paper describes flexible tools for specifying design variations that are based on nonuniform profile tolerance definitions. These tools specify bounds of design performance that can be used for negotiation among engineers in a collaborative design process. These specification methods allow for the capture of many different design functions that are not easily described with current tool designs. In addition, these specification methods lend themselves to efficient verification methods. Profile tolerance definitions provide the most general variation controls for complex mechanical surfaces. Common design practices and engineering standards for profile tolerances exhibit many weaknesses and limitations. We present a rationale …

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Comment On ‘‘Destructive Effect Of Disorder And Bias Voltage On Interface Resonance Transmission In Symmetric Tunnel Junctions’’, Julian P. Velev, Kirill D. Belashchenko, Evgeny Y. Tsymbal Mar 2006

Comment On ‘‘Destructive Effect Of Disorder And Bias Voltage On Interface Resonance Transmission In Symmetric Tunnel Junctions’’, Julian P. Velev, Kirill D. Belashchenko, Evgeny Y. Tsymbal

Nebraska Center for Materials and Nanoscience: Faculty Publications

In a recent Letter Tusche et al. [1] showed that a complete and coherent FeO layer forms on both interfaces of a FejMgOjFe|001| magnetic tunnel junction (MTJ) when using oxygen-assisted growth. Their ab initio model for these MTJs predicted tunneling magnetoresistance (TMR) of several thousand percent due to the contribution from interface resonances (IRs) perfectly matched at the two interfaces. In this Comment, we show that in practice the predicted giant TMR is unfeasible because the IRs are mismatched by structural disorder and/or by applied bias voltage resulting in a moderate TMR.

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In Vitro Toxicity Of Aluminum Nanoparticles In Rat Alveolar Macrophages, Andrew J. Wagner Mar 2006

In Vitro Toxicity Of Aluminum Nanoparticles In Rat Alveolar Macrophages, Andrew J. Wagner

Theses and Dissertations

Nanomaterials, which are by definition in the 1 - 100 nanometer range, have numerous possible benefits to society, but currently there is a lack of data that characterizes these materials effects on human health and environment. In general nanomaterials are of interest to the Air Force because of their applications in electronics, sensors, munitions and energetic/reactive systems. Nanoparticles such as aluminum have been considered for enhancing propulsion in solid rocket fuel. To date, only a few studies have looked at the toxicological effects of direct exposure to nanoparticles, none with aluminum. It is important to increase the understanding of the …

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Classification Characteristics Of Carbon Nanotube Polymer Composite Chemical Vapor Detectors, Huynh A. Hinshaw Mar 2006

Classification Characteristics Of Carbon Nanotube Polymer Composite Chemical Vapor Detectors, Huynh A. Hinshaw

Theses and Dissertations

The first step in combating a chemical weapons threat is contamination avoidance. This is accomplished by the detection and identification of chemical agents. The Air Force has several instruments to detect chemical vapors, but is always looking for lighter, faster, and more accurate technology for a better capability. This research is focused on using carbon nanotube polymer composite sensors for chemical detection. More specifically, models are developed to classify three sets of sensor data according to vapor using various multivariate techniques. Also, prediction models of a mixed sensor output are developed using neural networks and regression analysis. The classifiers developed …

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Characterization Of The Field Emission Properties Of Carbon Nanotubes Formed On Silicon Carbide Substrates By Surface Decomposition, Michael C. Pochet Mar 2006

Characterization Of The Field Emission Properties Of Carbon Nanotubes Formed On Silicon Carbide Substrates By Surface Decomposition, Michael C. Pochet

Theses and Dissertations

Dense arrays of vertically aligned carbon nanotubes (CNTs) form on the surface of silicon carbide wafers during high temperature anneals under moderate vacuum conditions. The novelty of this growth method is that the CNTs form without the aid of a metal catalyst, allowing for potentially impurity-free CNTs to form. In this study, CNT films were grown by the surface decomposition of silicon carbide substrates. The associated field emission characteristics were investigated to determine if films grown using this method possessed advantages over films grown using metal-catalyzed methods. The associated turn-on and threshold voltages, maximum current density, and emission current stability …

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Electroless Nickel Plating On Carbon Nanotube With Non-Palladium Activation Procedure, Guang-Hui Hu, Hui-Huang Wu, Fang-Zu Yang Feb 2006

Electroless Nickel Plating On Carbon Nanotube With Non-Palladium Activation Procedure, Guang-Hui Hu, Hui-Huang Wu, Fang-Zu Yang

Journal of Electrochemistry

A new procedure of surface activation without using palladium salt was proposed for electroless nickel plating on carbon nanotubes.In the procedure,carbon nanotubes were oxidized by nitric acid and then neutralized with NaOH to create carboxyl surface groups which were used to adsorb Ni2+ ions,thereafter the adsorbed Ni2+ ions were chemically reduced into Ni nano-particles as a catalytic center for electroless nickel deposition,all these were further confirmed by infrared absorption spectra and electron microscopic observations.The results indicate that the procedure is feasible to electroless nickel plating on carbon nanotubes.The different morphology of deposits obtained from electroless plating was also …

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Electrochemistry And Structures Of Silicon Surface, Gregory X.Zhang Feb 2006

Electrochemistry And Structures Of Silicon Surface, Gregory X.Zhang

Journal of Electrochemistry

Accurate control and fabrication of silicon surface structures from atomic scale to micrometer scale,which may be randomly associated with surface roughness or have well defined patterns,is critical for the per-formance and reliability of electronic devices.Electrochemical reactions of silicon in solutions involved in wetcleaning and etching of silicon wafer play an importantrole in determining the structures of silicon surface.Atre-mendous amount of researches have been done in the last several decades to understand and control a range ofcomplex electrochemical reactions at silicon/solution interface and their relations to the resulted surface struc-tures.The findings generated from these research efforts have been compiled and integrated …

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Development On Hydriding/Dehydriding Kinetics Of Mg Nano-Materials For Hydrogen Storage, Wei Mo, Hong-Liang Sun, Hai-Chang Zhang, Hua-Bin Yang, Zuo-Xiang Zhou Feb 2006

Development On Hydriding/Dehydriding Kinetics Of Mg Nano-Materials For Hydrogen Storage, Wei Mo, Hong-Liang Sun, Hai-Chang Zhang, Hua-Bin Yang, Zuo-Xiang Zhou

Journal of Electrochemistry

The development of Mg nano-materials for hydrogen storage in the recent decade has been reviewed in this paper.It was shown the Mg nano-powders prepared by high-energy ball milling showed promising hydriding and dehydriding performance with the transition metal oxides and other types of hydrogen storage alloys(ABx)as the catalysts.

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Electrocatalytic Oxidation Of Glucose On Nano Pt/C Electrode, Cui-Lian Chen, Xiao-Lan Wei, Pei Kang Shen Feb 2006

Electrocatalytic Oxidation Of Glucose On Nano Pt/C Electrode, Cui-Lian Chen, Xiao-Lan Wei, Pei Kang Shen

Journal of Electrochemistry

Nano Pt/C electrocatalysts were prepared by intermittent microwave heating method.The electrooxidation of glucose on smooth Pt and～Pt/C electrodes has been studied and compared.The results showed that the electrochemical properties on nano Pt/C were improved due to the reduction of the overpotential and the increase in the kinetic rate.The surface area would be significantly increased when the particle size of the catalyst was reduced to nano-scale,resulting in the increase in the activity.The enhancement in the resistance to poisoning could be explained that the oxygen-containing species are easier to react with poisoning species on nano Pt/C and re-active the electrode.

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Special Photoelectrochemical Response Of Nano-Crystalline Tio2 Electrode, Bi-Bo Lan, Jian-Zhang Zhou, Yan-Yan Xi, Hong-Xiang Chen, Guang-Hua Yao, Zhong-Hua Lin Feb 2006

Special Photoelectrochemical Response Of Nano-Crystalline Tio2 Electrode, Bi-Bo Lan, Jian-Zhang Zhou, Yan-Yan Xi, Hong-Xiang Chen, Guang-Hua Yao, Zhong-Hua Lin

Journal of Electrochemistry

The nano-crystalline TiO2 electrodes were prepared by spread method,electrodeposition and sol-gel method.The experimental results show that the nano-crystalline TiO2 electrodes have special photoelectrochemical response-the photocrrent-potential curves appear peaks.The special photoelectrochemical behaviors of nano-(crystalline) TiO2  electrodes are ascribed to nano-structure as well as special light induced redox reaction mechanism of nano-crystalline semiconductor electrodes.

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The Effective Magnetoelectroelastic Moduli Of Matrix-Based Multiferroic Composites, Shashidhar Srinivas, Jiangyu Li, Y.C. Zhou, A.K. Soh Feb 2006

The Effective Magnetoelectroelastic Moduli Of Matrix-Based Multiferroic Composites, Shashidhar Srinivas, Jiangyu Li, Y.C. Zhou, A.K. Soh

Nebraska Center for Materials and Nanoscience: Faculty Publications

In this paper, we develop a mean field Mori-Tanaka model [T. Mori and K. Tanaka, Acta. Metall. 21, 571 (1973)] to calculate the effective magnetoelectroelastic moduli of matrix-based multiferroic composites, emphasizing the effects of shape and orientation distribution of second phase particles that have not been investigated before. Through a systematic study, it is observed that laminated composites are optimal for magnetoelectric coefficient a11, while fibrous composites are optimal for a33. In addition, these coupling coefficients are maximum when the second phase particles are aligned. It is also postulated that the large discrepancy between theoretical predictions …

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Self-Consistent Local Gw Method: Application To 3D And 4D Metals, Kirill D. Belashchenko, Vladimir P. Antropov, N.E. Zein Feb 2006

Self-Consistent Local Gw Method: Application To 3D And 4D Metals, Kirill D. Belashchenko, Vladimir P. Antropov, N.E. Zein

Nebraska Center for Materials and Nanoscience: Faculty Publications

The spectral densities for 3d and 4d transition metals are calculated using the simplified version of the self-consistent GW method employing the local (one-site) approximation and the self-consistent quasiparticle basis set. The results are compared with those given by the traditional local density approximation (LDA) and also with experimental x-ray photoemission and inverse photoemission spectra. While no systematic improvements over LDA are observed, this fully self-consistent many-body technique generates quite reasonable results and can serve as a practical prototype for further development of the many-body electronic structure theory.

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Nanoparticle-Induced Negative Differential Resistance And Memory Effect In Polymer Bistable Light-Emitting Device, Ricky J. Tseng, Jianyong Ouyang, Chih-Wei Chu, Jinsong Huang, Yang Yang Jan 2006

Nanoparticle-Induced Negative Differential Resistance And Memory Effect In Polymer Bistable Light-Emitting Device, Ricky J. Tseng, Jianyong Ouyang, Chih-Wei Chu, Jinsong Huang, Yang Yang

Department of Mechanical and Materials Engineering: Faculty Publications

Recently, electrical bistability was demonstrated in polymer thin films incorporated with metal nanoparticles [J. Ouyang, C. W. Chu, C. R. Szmanda, L. P. Ma, and Y. Yang, Nat. Mater. 3, 918 (2004)]. In this letter, we show the evidence that electrons are the dominant charge carriers in these bistable devices. Direct integration of bistable polymer layer with a light-emitting polymer layer shows a unique light-emitting property modulated by the electrical bistability. A unique negative differential resistance induced by the charged gold nanoparticles is observed due to the charge trapping effect from the nanoparticles when interfaced with the light-emitting layer.

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In Vivo Laparoscopic Robotics, Mark E. Rentschler, Stephen R. Platt, Jason Dumpert, Shane M. Farritor, Dmitry Oleynikov Jan 2006

In Vivo Laparoscopic Robotics, Mark E. Rentschler, Stephen R. Platt, Jason Dumpert, Shane M. Farritor, Dmitry Oleynikov

Department of Mechanical and Materials Engineering: Faculty Publications

Robotic laparoscopic surgery is evolving to include in vivo robotic assistants. The impetus for the development of this technology is to provide surgeons with additional viewpoints and unconstrained manipulators that improve safety and reduce patient trauma. A family of these robots have been developed to provide vision and task assistance. Fixed-base and mobile robots have been designed and tested in animal models with much success. A cholecystectomy, prostatectomy, and nephrectomy have all been performed with the assistance of these robots. These early successful tests show how in vivo laparoscopic robotics may be part of the next advancement in surgical technology.

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