bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical and Analytical Study of Reversed Flow and Heat Transfer in a Heated Vertical Duct
Authors: Yang C. S. , Jeng D. Z. , Yih K. A. , Gau C. , Aung Win
Published: May 2009

Both analytical and numerical calculations are performed to study the buoyancy effect on the reversed flow structure and heat transfer processes in a finite vertical duct with a height to spacing ratio of 12. One of the walls is heated uniformly and the opposite wall is adiabatic. Uniform air flow is assumed to enter the duct. In the ranges of the buoyancy parameter of interest here for both assisted and opposed convection, a reversed flow, which can be observed to initiate in the downstream close to the exit, propagates upstream as Gr/Re2 increases. The increase in the Reynolds number has the effect of pushing the reversed flow downstream. Simple analytical models are developed to predict the penetration depth of the reversed flow for both assisted and opposed convection. The models can accurately predict the penetration depth when the transport process inside the channel is dominated by natural convection. Local and average Nusselt numbers at different buoyancy parameters are presented. Comparison with the experimental data published previously was also made and discussed. Good agreement confirms many of the numerical predictions despite simplifications of the numerical process made, such as two-dimensional and laminar flow assumptions.
A Study on Flow Transition and Development in Circular and Rectangular Ducts
Authors: Zanoun E.-S. , Kito M. , Egbers C.
Published: May 2009

The present paper reports observations on some aspects regarding the dependence of the transition Reynolds number and flow development on the inlet flow conditions and the entrance length in circular and rectangular ducts for Rem≤106×103, where Rem is the Reynolds number based on the bulk flow velocity (U¯b) and the duct integral length scale (D). The hot-wire anemometer was used to carry out measurements close to the circular duct exit; however, the laser-Doppler anemometry was utilized for the rectangular duct measurements. Particular considerations were given to the bulk flow velocity, the mean-velocity profile, the centerline-average-velocity, and the centerline turbulence statistics to the fourth order. Transition criteria in both ducts were discussed, reflecting effects of flow geometry, entrance flow conditions, and entrance length on the transition Reynolds number. A laminar behavior was maintained up to Rem≈15.4×103 and Rem≈2×103 in the circular and rectangular ducts, respectively, and the transition was observed to take place at different downstream positions as the inlet flow velocity varied.
A Numerical Investigation of the Flow Past a Generic Side Mirror and its Impact on Sound Generation
Authors: Ask Jonas , Davidson Lars
Published: May 2009

The case investigated is the flow past a generic side mirror mounted on a flat plate at the Reynolds number of ReD=5.2×105 based on the mirror diameter. The present work studies both flow and acoustic sources by evaluating two second-order advection schemes, different levels of turbulence modeling, and three different grids. The advection schemes discussed in the present study are a second-order upwind scheme and a monotonic central scheme. The turbulence models investigated cover three levels of modeling. These are the original formulation of the detached eddy simulation (DES) model, the Smagorinsky–Lilly sub-grid scale (SGS) model with near-wall damping, and a dynamic Smagorinsky model. The different grids are as follows: a primary grid where all parameter studies are conducted and a second grid with significantly higher wake resolution and to some extent also increased plate resolution, while maintaining the resolution at the front side of the mirror. The final grid uses a significantly higher plate resolution and a wake resolution similar to that of grid two, but a comparably lower mirror front side resolution as compared with the two other grids. The general outcome of this work is that the estimation of the grid cutoff frequency through a relation of the velocity fluctuation and the grid size matches both the experimental results and trend lines perfectly. Findings from the flow field show that the horseshoe vortex in front of the mirror causes pressure fluctuations with a magnitude exceeding the maximum levels at the rear side of the mirror. Its location and unsteady properties are perfectly captured in the final simulation as compared with the experiments conducted by Daimler–Chrysler. A laminar separation at the front side of the mirror is more or less found for all wall resolved cases except the DES simulation. The third grid fails to predict this flow feature, but it is shown that this effect has no significant effect on either the static pressure sensors at the mirror surface or at the dynamic sensors located downstream of the mirror. The simulation also supports the fundamental frequency based on the eddy convection in the mirror shear layer, which is shown to be twice as high as the frequency peak found in the lateral force spectra.
Drag Reduction Due to Cut-Corners at the Front-Edge of a Rectangular Cylinder With the Length-to-Breadth Ratio Being Less Than or Equal to Unity
Authors: Kurata Mitsuo , Ueda Yoshiaki , Kida Teruhiko , Iguchi Manabu
Published: May 2009

The flow past a rectangular cylinder with small cut-corners at the front-edge is investigated to discuss a relation between drag reduction and the cutout dimension. The rectangular shape is selected in eleven kinds of the length-to-breadth ratio from 2/6 to 6/6 (square prism) with the small rectangular-shaped cut-corners at the front-edge. The wind tunnel experiment is carried out to obtain time-averaged hydrodynamic forces measured by the force transducer at Re≈50,000. The contour map of the hydrodynamic coefficients with respect to the cutout dimension are shown to investigate the relation between the drag reduction and the cutout shape. In the contour map for the zero angle of attack, the region of the effective drag reduction achieved, in which the value of the drag coefficient is less than that of a circular cylinder at the same Reynolds number, is observed to become wide with the increase in the length-to-breadth ratio and it is independent of the angle of attack, α, within α being small. Furthermore, it is shown that there is a condition in which the drag reduction of CD⪅1.5 can be achieved even when the Strouhal number is less than 0.2.
A Novel Explicit Equation for Friction Factor in Smooth and Rough Pipes
Authors: Avci Atakan , Karagoz Irfan
Published: May 2009

In this paper, we propose a novel explicit equation for friction factor, which is valid for both smooth and rough wall turbulent flows in pipes and channels. The form of the proposed equation is based on a new logarithmic velocity profile and the model constants are obtained by using the experimental data available in the literature. The proposed equation gives the friction factor explicitly as a function of Reynolds number and relative roughness. The results indicate that the present model gives a very good prediction of the friction factor and can reproduce the Colebrook equation and its Moody plot. Therefore, the new approximation for the friction factor provides a rational, accurate, and practically useful method over the entire range of the Moody chart in terms of Reynolds number and relative roughness.
HYPERFINE MIXING AND THE SEMILEPTONIC DECAYS OF DOUBLE-HEAVY BARYONS IN A QUARK MODEL
Authors: ROBERTS W. , PERVIN MUSLEMA
Published: May 2009

The semileptonic decays of the lowest-lying double-heavy baryons are treated in a quark model. For the Ξbb, hyperfine mixing in the spin wave function leaves the total rate for decay into the lowest lying daughter baryons essentially unchanged, but changes the relative rates into the Ξbc and [Formula: see text]. The same pattern is obtained in the decays of the Ωbb. For the Ξbc, this mixing leads to factor of about 17 suppression in the decay rate to the [Formula: see text] when wave functions truncated to the largest components are used, but the total semileptonic decay rate of the parent baryon remains essentially unchanged. For the Ωbc, the decay to the [Formula: see text] is suppressed by a factor of more than 25 from the unmixed case. When the full wave functions are used, the large suppression of the decays to the [Formula: see text] and [Formula: see text] persists.
REAL-TIME GAIT PLANNING FOR THE HUMANOID ROBOT Rh-1 USING THE LOCAL AXIS GAIT ALGORITHM
Authors: ARBULU MARIO , BALAGUER CARLOS
Published: May 2009

This paper presents the 3D foot and center of gravity motion planning for the humanoid robot called the "local axis gait" (LAG) algorithm. It permits walking on different kinds of surfaces, such as planes, ramps or stairs. Furthermore, continuous change of the step length and orientation in real time will be possible, due to the real-time linear dynamics model of the walking pattern of the humanoid. The robot model is based on the cart table formulation for planning the center of gravity (COG) and zero moment point (ZMP) motion. The proposed algorithm takes into account physical robot constraints such as joint angles, angular velocity and torques. Torques are computed by the Lagrange method under screws and Lie groups. The LAG is divided into several stages: computation of the footprints; the decision of the ZMP limits around the footprints; the dynamic humanoid COG motion generation based on the cart table model; and joining the footprints of the swing foot by splines. In this way it is possible to generate each step online, using the desired footprints as input. In order to compute the joint torque limits, the Lagrangian method is used under the Lie groups and screw theory. The paper presents and discusses some successful results on the LAG in the full-size humanoid robot Rh-1 developed in the Roboticslab of University Carlos III of Madrid.
STRATEGIC ENVIRONMENTAL ASSESSMENT IN FINLAND: AN EVALUATION OF THE SEA ACT APPLICATION
Authors: SÖDERMAN TARJA , KALLIO TUOMAS
Published: May 2009

Experiences from the Finnish Strategic Environmental Assessment (SEA) Act were studied by surveying 35 SEA processes. Integration of plan or programme preparation and assessment, organisation of assessment, public participation and consultation, treatment of alternatives, scoping, impact assessment methods, effectiveness, environmental reporting, follow-up, effects on plan or programme preparation, assessment costs and consistency of the assessment were examined and evaluated. The results suggest that SEA is not yet used properly in decision-making. Several shortcomings characterised assessment practices in public participation, establishment and comparison of alternatives, definition of environmental problems, recognition of significant impacts and readiness to use SEA as a planning tool to integrate environmental considerations into the planning. In consequence, the assessments had only minor effects on the adopted plans and programmes. The most critical challenges in Finnish SEA practise are focusing on the most significant environmental issues and strengthening the links between planning, participation and decision-making.
ASTEROID IMPACTS OR NUCLEAR EXPLOSIONS IN THE NORTHERN PART OF BLACK SEA AND RISKS FOR POISONING THE INLAND POPULATION
Authors: BADESCU VIOREL
Published: May 2009

The impact of a large asteroid or a nuclear explosion in Black Sea may cause a catastrophic poisonous gas ( H2S ) release in the atmosphere. Some effects of this phenomenon are evaluated. The land surface area covered by the H2S cloud generated by a 1,000 m size asteroid ranges between about 5,760 km2and 9,920 km2. This may affect between 1,400,000 and 2,470,000 people. In case of a 70 m size asteroid, the cloud covers between 105 km2and 210 km2and 26,000 to 52,000 people may be affected. The evaluations may be a few times underestimated for some particular wind directions. Nuclear explosions of 1 Mton and 50 Mton TNT may be assimilated to the impact by asteroids of about 33 m and 120 m diameter, respectively. The social effects of these events may be diminished if some general procedures are implemented.
Intrinsic Properties of 40 nm-sized LiFePO4 Particles
Authors: Zaghib Karim , Mauger Alain , Kopec Monika , Gendron Francois , Julien C. M.
Published: May 2009

LiFePO4 particles of sizes in the range 35-45 nm have been prepared by jet-milling route. The bulk and surface properties have been investigated by a combination of XRD, TEM, FTIR, and magnetic measurements before and after the carbon coating of the particles intended to optimize the electrochemical performance of the powder used as a cathode element. The particles are crystallites free from impurity and defect, surrounded by a surface layer. Before carbon coating, the surface layer is highly disordered, inside which the iron ions are in the Fe3+ low spin (S=1/2) configuration. The disorder is found to have dramatic effects on the electrochemical properties as it stabilizes the solid solution inside the passivation layer. This disorder is strongly reduced by the carbon coating at 750 {degree sign}C, which switches the Fe3+ ions in the surface layer to the high spin (S=5/2) configuration, and restores the plateau of the voltage versus capacity. The results are discussed in the context of the controversy on the shrinking of the miscibility gap upon decreasing the size of the particles to the nanoscale.
Electrochemically Reversible Sodium Intercalation of Layered NaNi0.5Mn0.5O2 and NaCrO2
Authors: Komaba Shinichi , Nakayama Tetsuri , Ogata Atsushi , Shimizu Takaya , Takei Chikara , Takada S , Hokura A , Nakai I
Published: May 2009

Electrochemical activities of NaNi0.5Mn0.5O2 and NaCrO2, having the analogous layered structure to LiCoO2, were investigated in 1 mol dm-3 NaClO4 propylene carbonate at room temperature. Almost all sodium ions were extracted from the NaNi0.5Mn0.5O2 and NaCrO2 electrodes by galvanostatic oxidation to 4.5 V accompanied with several phase transitions. Layered NaNi0.5Mn0.5O2 electrode showed a highly reversible capacity of 185 mAh g-1 as positive electrode in Na cell in the potential region between 2.5 and 4.5 V versus Na. A NaCrO2 electrode was hardly electroactive after oxidation up to 4.5 V. When galvanostatic cycling was carried in the limited potential domain between 2 and 3.5 V, both electrodes showed discharge capacities of 100 - 120 mAh g-1 with satisfactory capacity retention. Layered LiCrO2 (R-3m) and NaCrO2 (R-3m) possess the quite similar crystal structures and the same transition metal, nevertheless they were inactive and active in Li and Na cells, respectively.
Mechanism of Lithium Intercalation in TiO2-brookite
Authors: Koudriachova Marina V. , Matar Mohamed
Published: May 2009

Ab initio calculations were applied to study Li-intercalation properties of brookite-structured titanium dioxide. This material shows a striking increase in Li-uptake upon decrease of the particle size, from negligible intercalation in the polycrystalline phase to full loading in the nanophase. Li-intercalation is predicted to be homogeneous over a wide range of insertion concentrations and limited by highly anisotropic diffusion of Li-ions. Calculations show that the intercalation process is dominated by strong deformations of the lattice resulting in preferential occupation of interstitial sites by Li-ions and their trapping at the beginning of discharge.
Structure and Electrochemical Hydrogen Storage Properties of Mg-Ti Based Materials Prepared by Mechanical Alloying
Authors: Rousselot Steeve , Bichat Marie-Pierre , Guay Daniel , Roué Lionel
Published: May 2009

High energy ball milling was used to prepare Mg100-xTix -10 wt.% Pd compounds, with x ranging from 20 to 80. X-ray diffraction analyses combined with Rietveld refinement shows that the as-milled compounds are made of a mixture of hcp and bcc phases in various proportions depending on the Mg/Ti ratio in the initial mixture. The electrochemical hydrogen absorption capacities of these compounds were assessed in KOH electrolyte. The number of activation cycles and the maximum discharge capacity value are strongly dependant on the material composition. The highest hydrogen discharge capacity (475 mAh g-1) is obtained with Mg50Ti50-10 wt.% Pd compound. Upon hydrogenation, the crystalline structure of the compound evolves into an fcc phase with a lattice parameter of 4.40 Aå.
Correspondence between Electrochemical Fluctuations and Phenomenon for Localized Corrosion of Less-Noble Metals
Authors: Itoi Yasuhiko , Take Seisho
Published: May 2009

Abstract. The application of electrochemical noise (Fluctuation) analysis for localized corrosion have been studied. Foils of zinc, aluminum and magnesium were used as specimens for electrochemical cell simulating localized corrosion. Time variations of short circuited potential and current were measured in these solutions, and simultaneously the surfaces of specimens were observed using microscope with television monitor. Two types fluctuation were detected. In the case of aluminum and magnesium, It was seemed that the fluctuations result from hydrogen evolution on the active site in the crevice. In the case of magnesium, fluctuations appeared on the trendy component of the corrosion potential. And that was random one. It was seemed that these fluctuations result from the hydrogen evolution on the active site in the crevice of magnesium from the microscopic observation. In the case of zinc, It was seemed that the fluctuations result from the dissolution on the active site in the crevice and generation of corrosion products on the cathodic site on the outer site.
Effect of Aspect Ratio of Artificial Pits Formed on Anodized Al by PRM on Localized Corrosion in Chloride Environments
Authors: Sakairi Masaotoshi , Kageyam Akihiro , Kojima Yoichi , Oya Yoshiyuki , Kikuchi Tatsuya
Published: May 2009

New in solution type artificial pit formation with area selective electrochemical measurement technique was established. Artificial pits were formed on anodized 1070 aluminum in solutions by continuous focused pulse YAG laser beam irradiation. The aspect ratio (pit depth/pit width) of formed pit can be changed from 0.45 to 1.23 by controlling laser beam irradiation time. As applying constant potential while laser irradiation in chloride environments, localized dissolution was occurred only at the laser beam irradiated area, because of the anodic oxide film act as insulator. The corrosion current increases with increasing aspect ratio at the same applied potential, however, aspect ratio of the pit does not show an influence on repassivation behavior of 1070 aluminum alloy.
Influence of Conversion Coating Conditions with Rare Earth Elements on Corrosion Resistance of Mg Alloys
Authors: Uesaka Nobuo , Shikai Yuichi , Takenaka Toshihide
Published: May 2009

Influence of the conversion coating with some rare-earth elements, such as La, Y, Sm, Nd and Ce, on corrosion resistance of Mg alloy has been studied. Effect of pretreatment, such as the alkaline degrease, acid pickling and surface activation, has been also investigated. The surface of Mg alloy was covered with the so-called dry mad structure by the coating. The coating layer was a thin oxide film containing Mg, Al and rare earth element. F and P were detected in the coating with the pretreatment in addition. The corrosion resistance of Mg alloy against salt water was significantly improved by the conversion coating by immersion in the solution including both Mg(NO3)2 and rare earth nitrate. The corrosion resistance was improved by applying the pretreatment, further.
The Effect of Phosphate Source on the Post-treatment of Cerium Based Conversion Coatings on Al 2024-T3 and its Correlation to Corrosion Performance
Authors: Heller Daimon K. , Fahrenholtz William G. , O'Keefe Matthew J.
Published: May 2009

The surface morphology, electrochemical characteristics, and salt spray corrosion performance was studied for cerium-based conversion coatings (CeCCs) that were post-treated in heated aqueous solutions of orthophosphate, pyrophosphate, and polyphosphate compounds. Phosphate post-treatment reduced cracking in the coatings, which resulted in better corrosion protection compared to coatings that were highly cracked or contained other defects. In addition, post-treatment in orthophosphate solutions converted the as-deposited hydrated cerium oxide to hydrated CePO4, which further improved corrosion protection. Electrochemical analyses showed that CeCCs that contained hydrated CePO4 after post-treatment had the highest resistance (~100 kΩ-cm2), most noble pitting potentials (~ -270 mV), and best corrosion protection of the post-treatments that were tested. While pyrophosphate and polyphosphate post-treatments reduced cracks in the film, they did not promote formation of CePO4⋅H2O. The results suggest that the corrosion protection of CeCCs on Al 2024-T3 is dependent on both the surface morphology and phase of the coating.
Applicability of a New Method for Selecting Weathering Steel for Bridges
Authors: Ohya Makoto , Takebe Masamichi , Adachi Ryo , Ota Junya , Kitagawa Naoki , Matsuzaki Yasuhiko , Aso Toshihiko
Published: May 2009

In this study, a new method for selecting weathering steel was applied to weathering steel bridges to be built in Matsue. To measure the corrosion loss over one year, a short-term exposure test was carried out using new type test specimen (50mm x 50mm x 2mm/t). The applicability of the method and other issues are discussed on the basis of exposure testing results and observation of the environments. Though the environment in the research area is very corrosive, the exposure testing results indicated that it is possible to use weathering steel, provided the appropriate product is selected.
The Influence of Galvanic Coupling on Corrosion of Carbon Steel Coupled with Stainless Steels for Use in Concrete Structures
Authors: Qian Shiyuan , Qu Deyu
Published: May 2009

The judicious use of stainless steel and carbon steel in concrete structures-using stainless steel only in areas with a high risk of corrosion and carbon steel in low-risk areas-could be a viable option for reducing lifetime cost, and extending service life. However, the concern about the risk of galvanic corrosion between the two different steels has prevented this application in the field. This paper investigates the galvanic coupling behaviours of carbon steel and three different stainless steels (304LN, 316LN and 2205). The results indicate that the oxygen reduction reaction is a rate-determining step and is much lower on stainless steel than on passive carbon steel. Therefore, the galvanic coupling current between stainless steel and corroding carbon steel is lower than the coupling current between passive and corroding carbon steels. Consequently, the combination of stainless steel with carbon steel will not increase the risk of corrosion of carbon steel.
Chloride Ion Effects in the Corrosion Kinetics of Fe-Ni Alloys
Authors: Nguyen N. L. , Nobe Ken
Published: May 2009

Experimental electrodissolution rates of Fe, Ni and Fe-Ni alloy in chloride-free perchlorate solutions and low and high concentrations of acidic chloride solutions have been examined. Both Fe and Fe-5Ni electrodissolution followed the Bockris mechanism with negative first order with respect to H+ and anodic Tafel slopes of 40mV/dec for Cl--free highly acidic perchlorate solutions while Ni was also first order but with anodic Tafel slopes of 60mV/dec. For concentrated acidic chloride solutions, Fe, Ni and Fe-5Ni were positive first order with respect to both H+ and Cl-; anodic Tafel slopes of Fe and Fe-5Ni were 2RT/F while Ni was 75mV/dec. At lower acidic chloride solutions, all three metals followed negative half-order with respect to H+ and positive half-order with respect to Cl-.
In-flight Microplasma Synthesis of Luminescent Silicon Quantum Dots in Macroscopic Quantities
Authors: Nozaki Tomohiro
Published: May 2009

In-flight microplasma synthesis of luminescent silicon nanocrystals (Si-NCs) is presented. A mixture of SiCl4 and H2 is activated in the high pressure (10 kPa), miniaturized (200 μl) non-thermal plasma reactor. High pressure condition accelerates cluster nucleation via three-body reaction, while a miniaturized reactor suppresses excess crystal growth due to short residence time, leading to 3−5 nm crystalline nanoparticles: process yield of 30−100 mg/h of luminescent Si-NCs was demonstrated. Crystallinity of as-produced silicon nanoparticles increased with increasing either input power or initial H2 content in the feed gas. Strong photon absorption in the short wavelength (less than 450 nm) and associated red-photoluminescence due to quantum confinement effect was confirmed.
Alkylated Silicon Nanocrystals: Electronic and Optical Characterization and their Potential Applications
Authors: Siller Lidija , Coxon Paul , Bangert Ursel , Gass Mhairi , Chao Yimin , Horrocks Benjamin
Published: May 2009

Alkylated Si nanocrystals could find applications as fluorescent tracers in biology, in optoelectronics and in floating gate devices. As a consequence, their structure and composition will have a critical bearing on the performance of any future nanocrystal-based device and so reliable chemical and structural characterization is essential. In this work we present an optical and atomic force microscopy study of Si nanocrystals deposited on glass and n-type Si (111) surfaces by evaporation of passivated silicon nanocrystals which show that controlled deposition of the macroscopic quantities needed for thin film formation is readily achieved. UV/Visible emission from these films, excited by 140 eV photons, was measured and shows a clear vibrational progression - up to six vibrational bands are visible at room temperature.
The Influence of Structural Ordering on Luminescence from Nitride- and Oxynitride-Passivated Silicon Nanoclusters
Authors: Wilson Patrick R. , Roschuk Tyler , Dunn Kayne , Betti Matthew , Wojcik Jacek , Mascher P.
Published: May 2009

Luminescent silicon nanoclusters have been formed in silicon-rich silicon nitride and silicon-rich silicon oxynitride films grown using inductively coupled plasma chemical vapour deposition. The luminescent properties and electronic structure of the films have been investigated through ultraviolet-excited photoluminescence and synchrotron-based X-ray absorption spectroscopy experiments at the Si K- and L3,2-edges, respectively. In the silicon-rich silicon nitride films, luminescence in the visible was observed from quantum confinement effects and inter-bandgap defect levels while X-ray absorption spectroscopy indicates a structural reordering of the silicon nanoclusters and nitride host matrix with increased silicon nanocluster phase separation, occurring at lower annealing temperatures in more silicon-rich films. Luminescence from the silicon-rich silicon oxynitride films appeared to be defect-related and only the silicon oxide and nitride host matrices exhibited structural reordering when annealed, while there was no change in the structure of the silicon nanoclusters.
Dielectric Bi3nbo7 (Bno) Thin Films Deposited on Polymer Substrates by Nano-Cluster Deposition for Flexible Electronic Device Applications
Authors: Lee Hyun-Woo , Seong Nak , Yoon Soon G.
Published: May 2009

High dielectric BNO thin films were deposited on Ni/Al/PES flexible substrates at low temperatures by Nano-Cluster Deposition (NCD) process. The Al(1x1mm2 top electrode size)/BNO(70nm)/Ni/Al/PES capacitors composed of BNO films deposited at 150oC on Ni/Al/PES substrates exhibit a dielectric constant of 62 and a dissipation factor of 8.0 % at 100 kHz. Capacitors with a top electrode size of 0.5x0.5 mm2 exhibited a leakage current density of approximately 3x10-4 A/cm2 at - 1.0 V.
Application of Chemical-mechanical Polishing for Planarizing a High-K Nano-composite Polyimide Insulator used in Organic Thin Film Transistors
Authors: Lee Wen-Hsi , Wang Chun Chieh , Ho Jia Chung
Published: May 2009

To solve the large leakage current of heavily blended nano-composite (PI and nano-TiO2 particles) with high capacitance gate dielectric film, chemical-mechanical polishing (CMP) was used to planarize the interface between the PI-TiO2 nano-composite film and pentacene. The hysteresis effect in OTFTs with the polished nano-composite dielectric surface was reduced because less charge was trapped in the interface. In pentacene OTFTs with high capacitance and a smooth surface, the threshold voltage improved from -22V to -5V, the sub-threshold voltage decreased from 3.44 to 0.50 (V/dec.), the current on/off ratio increased from 1.6x106 to 3.53x108, and the mobility increased from 0.416 to 0.624 (cm2V-1s-1).
Single and Dual nc-ITO and nc-ZnO Embedded ZrHfO High-k Nonvolatile Memories
Authors: Lin Chen-Han , Kuo Yue
Published: May 2009

MOS capacitors containing singe and dual nanocrystalline ITO and ZnO embedded in the Zr-doped HfO2 high-k gate dielectric were fabricated and characterized for nonvolatile memory functions. The nc-ITO and nc-ZnO embedded devices show mainly hole and electron trapping characteristics, respectively. The dual-layer nc-ITO and nc-ZnO embedded capacitors have more than double charge trapping capacities and faster charge rates than the single-layer embedded capacitors.
Impact of New Approach to Improve MOSFETs Performance with Ultrathin Gate Insulator
Authors: Cheng Weitao , Teramoto Akinobu , Ohmi Tadahiro
Published: May 2009

In this study, we focus on the difference behavior of the gate-channel capacitance (Cgc) characteristics in the inversion-mode (IM) and the accumulation-mode (AM) SOI MOSFETs. We experimentally demonstrate that the gate-channel capacitance in the AM MOS device is obviously larger than that in IM MOS device using the same gate insulator on the same wafer. The increase of the Cgc in AM MOSFETs is much more remarkable as downscaling the gate insulator due to the different inversion and accumulation layer quantization effect and poly-Si gate depletion effect. As the result, the current drivability has been obviously improved in the AM MOSFETs resulted from its vastly increased gate-channel capacitance, especially in the MOSFETs with the ultrathin gate insulator.
Process and Characterization of Hybrid-Oriented Complementary Single-Crystal Si Thin-Film Transistors on A Plastic Substrate
Authors: Pang Huiqing , Celler George K. , Ma Zhenqiang
Published: May 2009

We report the first flexible single-crystal Si complementary thin-film transistors (TFTs) based on hybrid-orientation technology (HOT) fabricated on plastic substrate. Silicon nanomembranes (SiNMs) from Si (001) and (110) source SOI wafers were integrated onto one plastic substrate. The complementary inverters consist of n-TFTs with a channel direction along Si (110)/<110> aligned side-by-side with p-TFTs along (001)/<110>, The gate lengths of both devices are 5 μm and gate widths are 15 μm and 30 μm for n- and p-TFTs respectively. Typical field-effect transistor performances were achieved from individual n- and p-TFTs. This work shows the potential hybrid inverters composed of n-TFTs along Si (001)/<110> and p-TFTs along (110)/<110>, which is believed to have an enhanced switching speed.
Advanced Design Methodology of High-Performance Sub-100-nm-Channel GAA MOSFET
Authors: Nakano Shunsuke , Hayashi Osanori , Omura Yasuhisa , Yamakawa Shinya , Wakabayashi Hitoshi
Published: May 2009

This paper reconsiders the design methodology of the short-channel GAA SOI MOSFET and proposes an advanced concept to enhance its performance. The new ideas are based on gate field engineering and source and drain diffusion engineering. Validity of the proposal is demonstrated by device simulations
Comparison of the Electrostatics of Bulk and SOI Trigate MOSFETs
Authors: Ruiz Francisco G. , Godoy Andres , Tienda-Luna Isabel , Gamiz Francisco
Published: May 2009

In this work we compare the electrostatic performance of bulk and SOI trigate MOSFETs. To do so, a self-consistent numerical solution of the two-dimensional Schrödinger and Poisson equations has been employed. The threshold voltage of bulk trigates is higher than that of SOI devices, due to the presence of a high-doping substrate, and this difference depends both on the device size and the substrate doping.
A Wide Range Temperature Sensor Using SOI Technology
Authors: Patterson Richard , Elbuluk Malik E. , Hammoud Ahmad
Published: May 2009

Silicon-on-insulator (SOI) technology is becoming widely used in integrated circuit chips for its advantages over the conventional silicon counterpart. The decrease in leakage current combined with lower power consumption allows electronics to operate in a broader temperature range. This paper describes the performance of an SOI-based temperature sensor under extreme temperatures and thermal cycling. The sensor comprised of a temperature-to-frequency relaxation oscillator circuit utilizing an SOI precision timer chip. The circuit was evaluated under extreme temperature exposure and thermal cycling between -190 {degree sign}C and +210 {degree sign}C. The results indicate that the sensor performed well over the entire test temperature range and it was able to re-start at extreme temperatures.
Simulation of Hole Mobility in DGSOI Transistors
Authors: Donetti Luca , Gamiz Francisco , Garcia Ruiz Francisco , Rodriguez Noel , Godoy Andres
Published: May 2009

In this paper we study carrier mobility in double gate SOI p-channel devices. A self-consistent solver for the six-band k•p and Poisson equations is employed to compute the wavefunctions and dispersion relations of hole subbands. Hole mobility is evaluated employing the Kubo-Greenwood formalism. Both phonon and surface roughness scattering mechanisms are taken into account. In the case of surface roughness scattering, an extension of a model previously developed for n-channel double gate devices has been developed. To do so, new assumptions were necessary to maintain reasonable simulation times as k•p approach is considered. The results show that volume inversion has a lower impact in DGSOI p-channel devices than the one shown for DGSOI n-channel devices.
Performance of Common-Source, Cascode and Wilson Current Mirrors Implemented with Graded-Channel SOI nMOSFETs in a Wide Temperature Range
Authors: De Souza Michelly , Flandre Denis , Pavanello Marcelo
Published: May 2009

This work presents an experimental comparative analysis of the behavior of current mirrors implemented with standard uniformly doped and Graded-Channel (GC) SOI nMOSFETs as a function of the temperature. Three different current mirror architectures were used, Common-source, Wilson and Cascode. The experimental results show that the use of Graded-Channel transistors promotes not only the increase of the output swing, but also the increase of the output resistance in all evaluated architectures, in comparison to the standard uniformly doped counterpart. Despite some degradation observed with the temperature reduction, current mirrors with GC transistors still present better performance than those implemented with standard SOI transistors.
Thermal Resistance Model for Multi-finger Trench-Isolated Bipolar Transistors on SOI Substrate
Authors: Rashmi R. , Kranti Abhinav , Armstrong G. Alastair , Nirgin Sydney
Published: May 2009

A simple predictive model to estimate the thermal resistance of a trench isolated multi-finger bipolar device on SOI substrate is proposed. The model shows very good agreement with 3-D electro-thermal simulations over a wide range of device parameters. The simulations have been verified with measurements. The model is virtually independent of critical device parameters such as trench depth, oxide layer thickness and emitter dimensions and serves as a useful tool to predict the thermal resistance of a multi-emitter device reasonably accurately, from the known thermal resistance of the corresponding single-emitter device.
Carbon Nanotubes Derivatized with Mediators for Laccase Catalyzed Oxygen Reduction
Authors: Bilewicz Renata , Stolarczyk Krzysztof , Sadowska Kamila , Rogalski Jerzy , Biernat Jan F
Published: May 2009

The construction of nanostructured biocatalytic electrode for the reduction of dioxygen to water is described. The novelty of the approach relies in the application single-walled carbon nanotubes (SWCNTs) covalently modified with redox mediator 2,2-azinobis-(3-ethylbenzothiazoline)-6-sulfonate) (ABTS) to communicate electronically the laccase active sites with the electrode. The nanotubes were modified either at the ends/defect sites or on the side walls. The ABTS moiety was connected with the nanotubes by the sulfonamide bond, which did not disrupt its electrochemical activity. The population of ABTS at the electrode surface was significantly larger when derivatization of the nanotubes was carried out at the walls. On the other hand, highest catalytic efficiency per mole of ABTS groups available at the electrode was achieved when SWCNTs were derivatized at the ends. This indicates that in the latter case, the conductive properties of the nanotubes play important role in the final catalytic activity of the nanostructured surface.
Responses of Poly(vinylferrocene) Film Redox-Driven Exchange Process to Codeposited and Ambient Anions
Authors: Jureviciute Irena , Bruckenstein Stanley , Hillman A. R.
Published: May 2009

We describe redox switching of polyvinylferrocene (PVF) films deposited from CH2Cl2 and sequentially exposed to aqueous solutions of three different charge neutralizing anions (BF4-, ClO4-, PF6-). EQCM charge and mass responses to PVF redox cycling in these aqueous media are combined to provide the potential dependence of ion and solvent fluxes for different experimental time scales. We find that the size of the anion initially introduced into a PVF film when it is deposited from CH2Cl2 determines the free volume that exists when the film is subsequently immersed in aqueous solution. We develop a model based upon free volume in which anions and solvent compete for space within the film. The model successfully predicts the result that the larger the anion the less solvent transfers, the effect of initially co-deposited anion on subsequently available free volume, and the decrease in mobile species transfers with decreasing time scale.
Spatially Averaging Electrodes
Authors: Sheth Disha , Diefes Richard , Gratzl Miklos
Published: May 2009

In contrast to many optical techniques, both the potentiometric and voltammetric measurement approach are only capable of reporting the concentration of the analyte of the sample solution that exists adjacent to the diffusion layer. Therefore, electrochemical measurement techniques in general cannot be used to assess 3D averaged bulk concentrations of inhomogeneous samples. This may pose a problem in very small samples which cannot be optically analyzed and where homogenization by stirring is difficult. We discuss the concept of spatially averaging electrodes that can, due to their designed geometry, report 3D spatially averaged bulk concentration of inhomogeneous samples that have some type of symmetry. Within a given type of symmetry an infinite variation of concentration distributions may exist. Electrode geometries for samples with two different types of symmetries, hemispherical and cylindrical, are discussed. Alternate designs with intrinsic redundancies to correct for any systematic errors in the measurement are also shown.
Whole-Blood Diagnostic Sensing System Based on Populational Platelet Rolling Behavior
Authors: Ricco Antonio J. , Kent Nigel J. , Lincoln Bryan , Meade Gerardene , Basabe Desmonts Lourdes , Lee Luke P. , MacCraith Brian D. , Corcoran Brian , Kenny Dermot
Published: May 2009

We are developing a point-of-care diagnostic sensor system for early warning of diseases or disorders involving the activation state of platelets. The system tracks platelet movement-adhering, releasing, rolling-along a well-characterized protein surface using customized image analysis to objectively quantify fluid-shear-mediated platelet-surface interactions for statistically meaningful numbers of platelets from a single blood sample. The fluidic device provides well-defined shear at the surface at physiological rate (~ 1500/s) and hydrodynamically focuses the sample stream into contact with the surface, providing assay results from < 200 µL of undiluted whole blood. Frame-by-frame object tracking of translocating platelets provides individual trajectories via a position-based probability function. Initial results show the relative fraction of time spent by platelets in the mobile relative to the stationary state is approximately 1.6 times longer for blood treated with abciximab (ReoPro) than for untreated normal blood.
Antibody-Antigen Equilibria in a Field of Magnetic Forces: Design of Reagentless Biosensors
Authors: Monson Christopher F. , Driscoll Laura N. , Khoie Shabnam , Bennion Eliot , Miller Cary J. , Majda Marcin
Published: May 2009

This project concerns a new strategy of detecting biological molecules that relies on competitive exchange interactions of an analyte with two-component molecular tethers attaching superparamagnetic microspheres (4 micron in diameter) to a sensor surface. The individual tethers consist of either double stranded DNA or antibody-antigen complex and are designed to selectively detect either specific ssDNA or antigenic proteins, respectively, in sensitive reagentless fashion. Performance of sensors was investigated using human cardiac troponin I, a serum heart attack marker, as an example of analytes of credible relevance to biomedical diagnostics.
The Development of an Amperometric Biosensor Based on the Assembly of Genetically Engineered Enzymes for the Detection of Explosives
Authors: Kalaji Maher , Gwenin Christopher , Kay Catherine
Published: May 2009

A series of nitroreductases containing sequences of cysteine amino acids, enabling strong thiolate bonds to form on a gold electrode surface without the loss of enzyme activity, were genetically engineered. The cysteines enable the orientationally controlled immobilisation of the enzymes, removing the need for pre-treatment of the electrode surface with self-assembled monolayers or conducting polymers. The enzymatically modified electrodes were utilised in the development of an amperometric biosensor for the detection of explosives containing nitro-aromatic compounds. Preliminary results demonstrate detection levels down to 5 parts per trillion, signifying tremendous promise towards an in situ sensor for the detection of vapours from explosive compounds.
Waveguide-Based Chemical and Spectroelectrochemical Sensor Platforms
Authors: Beam Brooke M. , Simmonds Adam , Veneman Peter A. , Ratcliff Erin , Mendes Sergio B. , Saavedra S. S. , Armstrong Neal R.
Published: May 2009

Here we review the progress in the development of waveguide-based spectroelectrochemical platforms, with special emphasis on the most recent technologies: the electroactive fiber-optic chip (EA-FOC) and chip-like spectroelectrochemical platforms using organic light emitting diode (OLED) light sources coupled with organic photovoltaic photodetectors (OPV-PD). Both technologies simplify spectroelectrochemical data collection through eliminating the need for free-space optics and benefit from the increased sensitivity of waveguide based devices producing new chemical sensor platforms.
Combinatorial Polymer Synthesis as a Tool in Biosensor and Biofuel Cell Development and Optimization
Authors: Ngounou Betrand , Guschin Dmitrii A. , Castillo John , Schuhmann Wolfgang
Published: May 2009

A strategy was established for the synthesis of redox electrodepo¬sition polymers (redox EDP) consisting of the synthesis of monomers with attached imidazolyl anchor groups, followed by radical copolymerization with a variety of monomers bearing side chains with different steric, hydrophobic, and electronic properties. The synthesized EDP were coordinatively modified by reaction with Os-bis-N,N'-(2,2'-bipyridyl)-dichloro complexes. The obtained redox-EDPs were precipitated on Pt electrodes by means of an electrochemically induced pH modulation in the presence of a pyrrolo¬quinoline quinone-dependent glucose dehydrogenase (PQQ-sGDH). The impact of the redox-EDPs composition on the electron transfer properties of the resulting reagentless glucose biosensors was investigated.
Spectroelectrochemical Sensor: Development and Applications
Authors: Heineman William R. , Seliskar Carl J. , Pinyayev Tatyana S. , Wilson Robert A. , Morris Laura K. , Del Negro Andrew S. , Bryan Samuel A.
Published: May 2009

The spectroelectrochemical sensor concept uses electrochemistry to modulate an optical signal to give improved selectivity. The sensor consists of an optically transparent electrode/waveguide coated with a thin film that preconcentrates the analyte. The sensor concept was first demonstrated with ferricyanide and later it was shown to work on a complex sample by detecting ferrocyanide in radioactive Hanford tank waste. Nafion, partially sulfonated polystyrene-block-polyethylene-ran-butylene)block-polystyrene (SSEBS), and quaternized poly(vinylpyridine) (QPVP) are examples of polymers used for the thin film. Detection limits achieved by the sensor are 10-5 to 10-8 M using change in absorbance as the mode of detection and about 10-10 M using fluorescence. A sensor has been developed for detecting [Re(dmpe)3]+ where dmpe = dimethylphosphinoethane, which serves as a nonradioactive analogue for complexes of radioactive 99Tc. Some polycyclic aromatic hydrocarbons have appropriate electrochemical and spectroscopic properties for spectroelectrochemical detection as demonstrated for 1-hydroxypyrene and its conjugate 1-hydroxypyrene-glucuronide.
New Approaches for Characterizing Sensor and Other Modern Complex Materials
Authors: Baer Don R. , Engelhard Mark , Felmy Andrew , Ford Joseph , Hu J. Z. , Lea Alan , Nachimuthu Ponnusamy , Saraf Laxmont , Sears Jesse , Thevuthasan Suntharampillai
Published: May 2009

Advances in understanding of sensor and other modern complex materials are often enabled by new research tools. This paper highlights three capability development themes used to identify new research tools to be provided to users of the U. S. Department of Energy's Environmental Molecular Sciences Laboratory. These capability development directions address the importance of dynamic measurements in realistic environments, the need for increased resolution in three dimensional analyses as well as the importance of linking theory and experiment. Capability development involves expanding the range of operation for a number of important techniques, developing and applying new capabilities, and advancing methods of data processing. Examples of current developments are provided including those related to magnetic resonance, x-ray diffraction, application of a focused beam capability to fuel cell aging, and near real time analysis of x-ray photoelectron spectroscopy spectra.
Toward a Combined SECM-IR-ATR System For the Investigation of Conductive Polymers
Authors: Wang Liqun , Moon Jong-Seok , Mizaikoff Boris , Kranz C.
Published: May 2009

Mid-infrared (MIR) spectroscopy has long been recognized as an important analytical technique widely applied for qualitative and quantitative analysis of materials such as e.g., complex biological or organic molecules. Microstructuring of conductive polymers and elucidating the mechanism of the polymerization play a major role in a variety of applications including sensing devices. Representative examples of such polymers are based on heterocyclic ﬁve-membered rings including e.g., polyaniline, polypyrrole, polythiophene, and their derivatives. Thus, scanning electrochemical microscopy (SECM) in combination with mid-infrared attenuated total reflection spectroscopy (IR-ATR) promises a versatile technique combining the benefits of in-situ electrochemistry with IR spectroscopy. Here, a single-bounce ATR crystal interrogated with IR radiation emanating from a Fourier transform infrared (FT-IR) spectrometer has been mounted such that the top-down combination with a home-built SECM setup has been facilitated, thereby enabling simultaneous IR-spectroscopic detection of localized electrochemically induced depositions via the SECM ultramicroelectrode.