bluuebunny/crossref_metadata_2025 huggingface dataset:
THE ISGUR–WISE FUNCTION IN AN IMPROVED QCD INSPIRED QUARK MODEL
Authors: CHOUDHURY D. K. , BORDOLOI NAMITA SHARMA
Published: March 2009

We calculate the Isgur–Wise function of heavy light mesons and its derivatives — its slope and its curvature, in an improved version of our earlier QCD Inspired Quark Model with two-loop static potential.
INVISIBLE Z DECAY WIDTH BOUNDS ON ACTIVE-STERILE NEUTRINO MIXING IN THE (3+1) AND (3+2) MODELS
Authors: DE S. PIRES C. A.
Published: March 2009

In this work we consider scenarios where light sterile neutrinos are mixed with the active ones. The active-sterile neutrino mixings render new contributions to the invisible Z decay width which will depend predominantly on the active-sterile mixing matrix elements. We then use the current experimental value of the invisible Z decay width to obtain bounds on these mixing matrix elements for both (3+1) and (3+2) models.
GEOMETRIZATION OF ELECTROMAGNETISM IN TETRAD-SPIN-CONNECTION GRAVITY
Authors: POPŁAWSKI NIKODEM J.
Published: March 2009

The metric-affine Lagrangian of Ponomarev and Obukhov for the unified gravitational and electromagnetic fields is linear in the Ricci scalar and quadratic in the tensor of homothetic curvature. We apply to this Lagrangian the variational principle with the tetrad and spin connection as dynamical variables and show that, in this approach, the field equations are the Einstein–Maxwell equations if we relate the electromagnetic potential to the trace of the spin connection. We also show that, as in the Ponomarev–Obukhov formulation, the generally covariant Dirac Lagrangian gives rise to the standard spinor source for the Einstein–Maxwell equations, while the spinor field obeys the nonlinear Heisenberg–Ivanenko equation with the electromagnetic coupling. We generalize that formulation to spinors with arbitrary electric charges.
A NOVEL IRIS LOCATION ALGORITHM
Authors: WANG ZHIFANG , HAN QI , BUSCH CHRISTOPH
Published: March 2009

Biometric technologies are becoming much more important in various applications. Among them, iris recognition is considered as one of the most reliable and accurate technologies. In the preparation of iris recognition, the iris location will influence the performance of the entire system. This paper proposes a novel algorithm to locate iris and eyelids. Morphological operation is applied to remove eyelashes during iris boundary location. An optimal step length is calculated to reduce the searching time. Experimental results demonstrate that the proposed iris location algorithm is able to achieve a good performance with accuracy higher than 97.6%.
NEGATIVE RESISTANCE ACTIVE RESISTOR WITH IMPROVED LINEARITY AND FREQUENCY RESPONSE
Authors: POPA COSMIN
Published: March 2009

An original active resistor circuit will be presented. The main advantages of the new proposed implementations are the improved linearity, small area consumption and improved frequency response. An original technique for linearizing the I(V) characteristic of the active resistor will be proposed, based on the utilization of a new linear differential amplifier, and on a current-pass circuit. The linearization of the original differential structure is achieved by compensating the quadratic characteristic of the MOS transistor operating in the saturation region by an original square-root circuit. The errors introduced by the second-order effects will be strongly reduced, while the circuit frequency response of the circuit is very good as a result of operating all MOS transistors in the saturation region. In order to design a circuit having a negative equivalent resistance, an original method specific to the proposed implementation of the active resistor circuit will be presented. The circuit is implemented in 0.35 μm CMOS technology, the SPICE simulation confirming the theoretical estimated results and showing a linearity error under a percent for an extended input range (± 500 mV) and a small value of the supply voltage (± 3 V).
LOW-POWER INSTRUCTION ADDRESS BUS CODING WITH XOR–BITS ARCHITECTURE
Authors: FAN CHIH-PENG , FANG CHIA-HAO
Published: March 2009

In this paper, we present an address bus coding method to reduce dynamic power dissipations and delay faults at on-chip applications. The purpose of the proposed new coding technique is to diminish the switching and coupling activities on instruction address busses effectively. The proposed bus coding method is called the exclusive-OR and bus inverter transition signaling (XOR–BITS) code. The XOR–BITS code has four advantages. Firstly, it can save a large number of switching activities. Secondly, it can also save a large number of coupling activities. Thirdly, its architecture belongs to a low-complexity architecture. Finally, its delay is short after optimizations. Experimental results show that the XOR–BITS coding indicates an average reduction in 78.5% switching activities and 21.9% coupling activities on instruction address busses. It surpasses the other address coding methods in total power dissipations when the load capacitance is more than 1 pF/bit with the TSMC 0.13 μm CMOS technology. For a 50 pF/bit load capacitance, it achieves a 74.9% average reduction in total power dissipations, compared with the un-coded schemes by using seven benchmarks. Similarly, our method also surpasses the other address bus coding methods with the TSMC 0.18 μm CMOS technology.
STUDYING ENERGY-ORIENTED DYNAMIC OPTIMIZATIONS IN JAVA VIRTUAL MACHINES
Authors: SUN YU , ZHANG WEI
Published: March 2009

Virtual machines have been increasingly used in embedded and mobile devices. Limited processing power and energy resources become a major challenge for modern virtual machines. The traditional virtual machines running on server computers also face the similar requirement to reduce energy dissipation. To address these challenges, a number of research works have been done in the area of energy-oriented dynamic optimization in Java Virtual Machines (JVM). Some of them focus on virtual machine directed hardware optimizations, while others exploit pure software approaches on virtual machine or compiler to reduce energy consumption. Additionally, client/server framework among multiple processors is also used to offload power-consuming tasks from low-power devices. This paper surveys the current progress of energy-oriented dynamic optimizations in JVMs.
PARALLEL AND RUNTIME RECONFIGURABLE IMPLEMENTATION OF THE IDEA ALGORITHM
Authors: GRANADO-CRIADO JOSÉ MARÍA , VEGA-RODRÍGUEZ MIGUEL ÁNGEL , SÁNCHEZ-PÉREZ JUAN MANUEL , GÓMEZ-PULIDO JUAN ANTONIO
Published: March 2009

Cryptographic algorithms are a fundamental tool nowadays, and information networks continue to grow exponentially every year. Moreover, these algorithms need to be very fast due to the new standards. In order to achieve this characteristic, a good choice is to use FPGAs, which mix the advantages of software flexibility and hardware performance. In this work, we present a super-pipelined and parallel implementation of the IDEA cryptographic algorithm by using partial and dynamic reconfiguration. Our implementation reaches a performance of 26.028 Gb/s, and therefore, it obtains better results than those found in the literature.
CURRENT MODE CMOS QUATERNARY LOGIC FULL-ADDER
Authors: KIM JEONG BEOM
Published: March 2009

This paper proposes a quaternary-to-binary logic decoder, a quaternary current buffer, and a quaternary full-adder using current-mode multiple-valued logic (MVL) CMOS circuits. The proposed full-adder is superior to the previous MVL CMOS circuit in both the circuit occupied area and the performance. Comparing with the binary logic full-adder, the proposed full-adder is superior in the circuit occupied area. However, the circuit performance is inferior to the binary logic full-adder. The validity and effectiveness of the proposed circuits are verified through the HSPICE under Hynix 0.25 μm standard CMOS technology with the supply voltage 2.5 V.
DISCRETE CHAOTIC DYNAMICS FROM CHUA'S OSCILLATOR: CHUA MACHINES
Authors: BILOTTA ELEONORA , PANTANO PIETRO
Published: March 2009

In previous work, the authors explored the parameter space for Chua's circuit and its generalizations, discovering new routes to chaos, and nearly a thousand new attractors. These were obtained by varying the parameters of the physical circuit and of systems derived from it. Here, we present a novel class of computational system that does not respect the classical constraints in Chua's circuit, and that generates chaotic dynamics via an iterative process based on discrete versions of the equations for Chua's circuit and its variants. We call these systems Chua Machines. After presenting the chaotic dynamics, we provide a formal description of Chua Machines and a Gallery of 222 3D images, illustrating their dynamics. We discuss the method used to discover these systems and the metrics applied in the exploration of their parameter space and offer examples of highly complex bifurcation maps, together with images showing how patterns can evolve with time, or vary significantly changing the values of one of the parameters. Finally, we present a detailed analysis of qualitative changes in a Chua Machine as it traverses the parameter space of the bifurcation map. The evidence suggests that these dynamics are even richer and more complex than their counterpart in the continuous domain.
THE DYNAMICS OF NQ-SYSTEMS IN THE PLANE
Authors: MENCINGER MATEJ , KUTNJAK MILAN
Published: March 2009

The dynamics of discrete homogeneous quadratic planar maps is considered via the algebraic approach. There is a one-to-one correspondence between these systems and 2D commutative algebras (c.f. [Markus, 1960]). In particular, we consider the systems corresponding to algebras which contain some nilpotents of rank two (i.e. NQ-systems). Markus algebraic classification is used to obtain the class representatives. The case-by-case dynamical analysis is presented. It is proven that there is no chaos in NQ-systems. Yet, some cases are really interesting from the dynamical and bifurcational points of view.
GLOBAL ANALYSIS ON n-SCROLL CHAOTIC ATTRACTORS OF MODIFIED CHUA'S CIRCUIT
Authors: XU FEI , YU PEI , LIAO XIAOXIN
Published: March 2009

In this paper, we present a further mathematical study on the report of existence of n-scroll chaotic attractors in a modified Chua's circuit. A series of results based on mathematical theory are given. First, we show that the chaotic attractors of the modified Chua's circuit are globally attractive, with estimations given for the globally attractive set and positive invariant set. Then, we study the positions, number and local stability of the equilibrium points. We also design simple feedback control laws to globally exponentially stabilize any given equilibrium point. Finally, we use the theory and methodology of absolute stability of Luré nonlinear control systems and nonlinear feedback control to exponentially synchronize two modified Chua's circuits with the same structure. The design of constructive feedback control laws for synchronization is also discussed.
A KICKED OSCILLATOR AS A MODEL OF A PULSED MEMS SYSTEM
Authors: BLOKHINA ELENA , FEELY ORLA
Published: March 2009

In this paper, we study the behavior of a MEMS oscillator by applying methods of nonlinear dynamics. We model the system as a kicked damped oscillator and obtain the iterative maps that describe the MEMS system. The dynamics of the maps are studied numerically: we present a study of limit cycles and their rotation numbers and show how the control parameters and initial conditions may affect the output frequencies.
A GENERALIZED MODEL OF ACTIVE MEDIA WITH A SET OF INTERACTING PACEMAKERS: APPLICATION TO THE HEART BEAT ANALYSIS
Authors: RYBALKO SERGEI , ZHUCHKOVA EKATERINA
Published: March 2009

We propose a fairly general model of active media by considering of the interaction between pacemakers via their phase response curves. This model describes a network of pulse oscillators coupled by their response to the internal depolarization of mutual stimulations.

First, a macroscopic level corresponding to an arbitrary large number of oscillatory elements coupled globally is considered. As a specific and important case of the proposed model, the bidirectional interaction of two cardiac nodes is described. This case is generalized by means of an additional pacemaker, which can be expounded as an external stimulator. The behavior of such a system is analyzed. Second, the microscopic level corresponding to the representation of cardiac nodes by two-dimensional lattices of pulse oscillators coupled via the nearest neighbors is described. The model is a universal one in the sense that on its basis one can easily construct discrete distributed media of active elements, which interact via phase response curves.
NEW ATTRACTORS AND NEW BEHAVIORS IN THE PHOTO-CONTROLLED CHUA'S CIRCUIT
Authors: RAHMA FADHIL , FORTUNA LUIGI , FRASCA MATTIA
Published: March 2009

In this brief communication, we introduce a Chua's circuit based on a photoresistor nonlinear device and experimentally investigate the effects of controlling it by a light source. Light control affects the dynamics of the circuit in several ways, and the circuit can be controlled to exhibit periodicity, period-doubling bifurcations and chaotic attractors. The dynamics of the circuit that operates at frequencies up to kilohertz is strongly influenced by using periodic driving signals at low frequencies. In particular, experimental results have shown that an unstable intermittent behavior can be observed and that this can be stabilized by using feedback. Synchronization of two circuits has also been investigated.
TWO-PARAMETER BIFURCATION CURVES IN POWER ELECTRONIC CONVERTERS
Authors: FOSSAS E. , HOGAN S. J. , SEARA T. M.
Published: March 2009

In this paper we prove the general result that, given a linear system [Formula: see text] where A is hyperbolic, u is piecewise linear and L-periodic, with [Formula: see text], then there exists a unique L-periodic solution x = xp(t) such that [Formula: see text]. We then consider a DC/DC buck (step-down) converter controlled by the ZAD (zero-average dynamics) strategy. The ZAD strategy sets the duty cycle, d (the length of time the input voltage is applied across an inductance), by ensuring that, on average, a function of the state variables is always zero. The two control parameters are v ref , a reference voltage that the circuit is required to follow, and ks, a time constant which controls the approach to the zero average. We show how to calculate d exactly for a periodic system response, without knowledge of the state space solutions. In particular, we show that for a T-periodic response d is independent of ks. We calculate period doubling and corner collision bifurcations, the latter occurring when the duty cycle saturates and is unable to switch. We also show the presence of a codimension two nonsmooth bifurcation in this system when a corner collision bifurcation and a saddle node bifurcation collide.
A NEW GENERALIZATION OF DELAYED FEEDBACK CONTROL
Authors: MORGÜL ÖMER
Published: March 2009

In this paper, we consider the stabilization problem of unstable periodic orbits of one-dimensional discrete time chaotic systems. We propose a novel generalization of the classical delayed feedback law and present some stability results. These results show that for period 1 all hyperbolic periodic orbits can be stabilized by the proposed method; for higher order periods the proposed scheme possesses some inherent limitations. However, some more improvement over the classical delayed feedback scheme can be achieved with the proposed scheme. The stability proofs also give the possible feedback gains which achieve stabilization. We will also present some simulation results.
PARTIAL STATE IMPULSIVE SYNCHRONIZATION OF A CLASS OF NONLINEAR SYSTEMS
Authors: WANG YAN-WU , WEN CHANGYUN , SOH YENG CHAI , GUAN ZHI-HONG
Published: March 2009

Impulsive synchronization of chaotic systems is an attractive topic and a number of interesting results have been obtained in recent years. However, all of these results on impulsive synchronization need to employ full states of the system to achieve the desired objectives. In this paper, impulsive synchronization that needs only part of system states is studied for a class of nonlinear system. Typical chaotic systems, such as Lorenz system, Chen's system, and a 4D hyperchaotic system, are taken as examples. A new scheme is proposed to select the impulsive intervals. After some theoretical analysis, simulation results show the effectiveness of the proposed synchronization scheme.
AN ITERATION METHOD WITH GENERALLY CONVERGENT PROPERTY FOR CUBIC POLYNOMIALS
Authors: TANG PEIPEI , WANG XINGHUA
Published: March 2009

In this paper, we first establish a rational iteration method which can be used as a root-finding algorithm for almost every polynomial. It has no nonrepelling extraneous fixed point in the complex plane and is generally convergent for both quadratic and cubic polynomials. Then some properties of this algorithm are given. By the aid of computer, we produce pictures of the Julia sets for the iterations of some polynomials. Numerical results show that it is a root-finding method with convergence order the same as Halley's method.
FLUID-STRUCTURE INTERACTION ANALYSIS OF WALL STRESS AND FLOW PATTERNS IN A THORACIC AORTIC ANEURYSM
Authors: TAN F. P. P. , TORII R. , BORGHI A. , MOHIADDIN R. H. , WOOD N. B. , XU X. Y.
Published: March 2009

In this study, fluid-structure interaction (FSI) simulation was carried out to predict wall shear stress (WSS) and blood flow patterns in a thoracic aortic aneurysm (TAA) where haemodynamic stresses on the diseased aortic wall are thought to lead to the growth, progression and rupture of the aneurysm. Based on MR images, a patient-specific TAA model was reconstructed. A newly developed two-equation laminar-turbulent transitional model was employed and realistic velocity and pressure waveforms were used as boundary conditions. Analysis of results include turbulence intensity, wall displacement, WSS, wall tensile stress and comparison of velocity profiles between MRI data, rigid and FSI simulations. Velocity profiles demonstrated that the FSI simulation gave better agreement with the MRI data while results for the time-averaged WSS (TAWSS) and oscillatory shear index (OSI) distributions showed no qualitative differences between the simulations. With the FSI model, the maximum TAWSS value was 13% lower, whereas the turbulence intensity was significantly higher than the rigid model. The FSI simulation also provided results for wall mechanical stress in terms of von Mises stress, allowing regions of high wall stress to be identified.
CYCLIC PLASTICITY MODELLING FOR ANDES THIN SHELL AND LINE-SPRING FINITE ELEMENTS
Authors: BERG ESPEN , HOLTHE KJELL , SKALLERUD BJØRN
Published: March 2009

This paper presents a proposed methodology to account for cyclic plastic response of the thin shell ANDES and line-spring finite elements. A through thickness integration scheme is employed for the shell element and stress resultant plasticity is used for the line-spring element. A simplified contact formulation to account for crack closure in the line-spring element is also presented. Numerical comparisons between the proposed models and detailed 3D analyses (pipes) are carried out and presented herein. A comparison between the present implementation and large scale experiment of a surface cracked pipe subjected to large cyclic plastic strains is also presented. The purpose of the presented implementation is to account for cyclic loading in pipeline technology where significant amount of plasticity in the loading cycles occurs.
The Ins and Outs of Leukocyte Integrin Signaling
Authors: Abram Clare L. , Lowell Clifford A.
Published: March 2009

Integrins are the principal cell adhesion receptors that mediate leukocyte migration and activation in the immune system. These receptors signal bidirectionally through the plasma membrane in pathways referred to as inside-out and outside-in signaling. Each of these pathways is mediated by conformational changes in the integrin structure. Such changes allow high-affinity binding of the receptor with counter-adhesion molecules on the vascular endothelium or extracellular matrix and lead to association of the cytoplasmic tails of the integrins with intracellular signaling molecules. Leukocyte functional responses resulting from outside-in signaling include migration, proliferation, cytokine secretion, and degranulation. Here, we review the key signaling events that occur in the inside-out versus outside-in pathways, highlighting recent advances in our understanding of how integrins are activated by a variety of stimuli and how they mediate a diverse array of cellular responses.
The Inflammasomes: Guardians of the Body
Authors: Martinon Fabio , Mayor Annick , Tschopp Jürg
Published: March 2009

The innate immune system relies on its capacity to rapidly detect invading pathogenic microbes as foreign and to eliminate them. The discovery of Toll-like receptors (TLRs) provided a class of membrane receptors that sense extracellular microbes and trigger antipathogen signaling cascades. More recently, intracellular microbial sensors have been identified, including NOD-like receptors (NLRs). Some of the NLRs also sense nonmicrobial danger signals and form large cytoplasmic complexes called inflammasomes that link the sensing of microbial products and metabolic stress to the proteolytic activation of the proinflammatory cytokines IL-1β and IL-18. The NALP3 inflammasome has been associated with several autoinflammatory conditions including gout. Likewise, the NALP3 inflammasome is a crucial element in the adjuvant effect of aluminum and can direct a humoral adaptive immune response. In this review, we discuss the role of NLRs, and in particular the inflammasomes, in the recognition of microbial and danger components and the role they play in health and disease.
Development and Testing of Series Hybrid Drive Vehicles for Military Applications
Authors: Nederhoed Richard , Walker Grayson W.
Published: March 2009

Since 1983, General Dynamics Land Systems has maintained an active development program in series hybrid electric drive vehicles comprised of a diesel engine coupled with a generator to provide electrical energy to a battery bank that powered in-hub permanent magnet motors to propel wheeled or tracked vehicles and supply both on-board and exportable electrical power. A development program with DARPA-ONR-USMC funded the RST-V program (Reconnaissance, Surveillance, and Tactical Vehicle) to provide the USMC with a vehicle capable of being transported on a V-22 aircraft and providing high mobility performance, silent watch and silent movement capabilities. Later the vehicle was used to combine exportable power (30 kW) in order to meet the growing demand for battlefield power. The in-hub electric motors on all 4 wheels of the RST-V was a key factor in providing high mobility, improved survivability, increased reliability, and increased interior payload space due to the lack of a drive shave/transmission. The increase in survivability becomes key because the vehicle could move on as few as 1 operating motor or without the use of the engine. More than 20,000 hours of testing have been completed leading to significant knowledge in battery management, power management, and system maintenance and reliability.
Novel Sn/C Composite Anode Material for Lithium-ion Batteries
Authors: Wang Hongqiang , Li Qingyu , Hu Sijiang , Wang Fangping , Yan Zhixiong
Published: March 2009

Sn/C composite was prepared by using cationic starch and sodium stannate. The obtained composite was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The morphology of the composite lies on the content of carbon. The results of TEM show the Sn/C composite with 38.6 wt% carbon has higher dispersivity. The composite's Electrochemical Performance was evaluated by galvanostatic cycling and cyclic voltammetry. The final result showed when carbon content of Sn/C composite was 38.6wt%, it had excellent cycle performance and higher capacity.
The Activity Determination of Single Cell by Isolation and Cultivation on a Centrifugal Flow Disk
Authors: Kubo Izumi , Furutani Shunsuke , Nagai Hidenori
Published: March 2009

In this study, we present centrifugal flow disk to isolate single cell and culture it from single cell simply and rapidly by combining the aligned microchambers and centrifugal force. In order to determine activity of single-cell, a centrifugal flow disk was designed and made of polydimethyl-siloxane (PDMS), which has gas permeability. On the disk 24 microchannels were arranged and along each channel 530 microchambers were aligned. To confirm the activity of isolated cell, cell suspensions of Eschericia coli, baker's yeast, Jurkat cell, and NIH3T3 cell are isolated by the rotation of the disk at 3000 rpm, 30 sec. After the isolation, cells of E. coli and baker's yeast were cultivated from the isolated single-cell to large amount of cells after 24 hours of incubation. As for Jurkat cells and NIH3T3 cells, two or three times of cell division were performed easily in these disks without medium exchange.
Magnetic Force-based Lab-on-a-chip for Single Cell Analysis in a Droplet
Authors: Okochi Mina , Tsuchiya Hiroyoshi , Kumazawa Fumitaka , Shikida Mitsuhiro , Honda Hiroyuki
Published: March 2009

Measurement of gene expression in individual cells has attracted attention as a tool for understanding the distribution of cellular responses to environmental stimuli. An integrated magnetic force based lab-on-a-chip (Mag-LOC) with a droplet-manipulation system was developed for gene expression analysis in a parallel manner. This system does not need mechanical fluidic devices such as pumps and valves for handling solutions. It can be used as a powerful tool for various biochemical applications by moving and coalescing sample droplets using magnetic beads immersed in mineral oil. The droplet containing magnetic beads and a cell was manipulated with the magnet located underneath the channel, and coalesced with lysis buffer. Using K562 cells as the leukemia model, the cell lyses and reverse transcription (RT)-PCR analysis were successfully performed at a single cell level for beta-2 microglobulin gene.
In Vivo Observation of Tissue Induction within an Animal Body
Authors: Inoue Yusuke , Nakagawa Hidemoto , Saito Itsuro , Kishi Ayumi , Isoyama Takashi , Shi Wei , Kouno Akimasa , Ono Toshiya , Miura Hidekazu , Chinzei Tsuneo , Imachi Kou , Abe Yusuke
Published: March 2009

Natural tissue induction process within an animal body was observed. A small implantable video camera system with a scaffold was developed. The camera system was implanted into a muscle section of a goat and induction process was observed for several months. Plural cell species that comprises muscle tissue were induced. Vigorous angigenesis was observed at the front region of tissue induction resulting dense distribution of capillary vessels and red blood cells. The density of capillary vessels reduced considerably behind the front region and arterioles and venules started to appear. Frequent interconnections of blood vessels as well as major blood flow route changes were observed.
The Effect of Nickel on the Local Corrosion Behavior of Amorphous Al-Cu-Mg Based Alloys
Authors: Aburada Tomohiro , Fitz-Gerald James M. , Scully J. R.
Published: March 2009

The effect of a minor amount of Ni on local corrosion behavior was investigated using Al-Cu-Mg amorphous alloys. Cyclic polarization studies revealed that the addition of a small amount of Ni can enhance both pitting and repassivation potentials significantly, in both the amorphous and devitrified crystalline state. The pit growth kinetics were also ennobled and slowed by the minor solute Ni. Electron microscopy analysis revealed a porous layer depleted with Al and Mg in pits, indicating preferential dissolution. The porous layer was finer in the presence of Ni. A new mechanism of corrosion is discussed. The possible roles of Ni are also discussed.
Metallurgical and Physical Factors in Improving the Corrosion Resistance of Thermally Sprayed Semi-Amorphous Al-Co-Ce Coatings
Authors: Tailleart Nicole R. , Gauthier Ben , Eidelman Shmuel , Scully J. R.
Published: March 2009

A high density, low porosity Al-Co-Ce metallic coating has been successfully applied to a AA-2024-T351 substrate using a pulsed thermal spray (PTS) process in thicknesses ranging from 100-500 micrometers. The three proposed modes of corrosion protection brought about by the coating (e.g., a localized corrosion barrier, a sacrificial anode to supply cathodic protection of any exposed AA 2024-T351, and active inhibitor release and protection of AA 2024-T351) have been verified to function simultaneously. Although XRD has identified nanocrystalline peaks in the as-sprayed deposit, the best PTS applied coating samples have approached the localized corrosion properties of fully amorphous melt spun ribbons of similar composition. However, high surface area PTS coatings produced superior capabilities for active inhibitor release.
Corrosion of a New Class of Solid Solution Al Alloys
Authors: Quirk Sarah E. , Birbilis Nick , Cavanaugh Mary K. , Hutchinson Christopher R. , Da Costa Teixeira Julien , Ringer Simon
Published: March 2009

Aluminum alloys derive their favorable mechanical properties from heterogeneous microstructures. The heterogeneity of these microstructures leads to localized corrosion. Whilst there has been intense research in localized corrosion in the past, a very important question remains unanswered: "How small is too small for microstructural features to behave as unique electrochemical entities or local corrosion hot-spots?" Our prior work has indicated that precipitates on the order of a few nm in size can indeed serve as unique electrochemical entities. In this work, we investigate the corrosion behavior of a new class of Al alloys based on inhomogeneous solid solutions. Through heat treatment, a spectrum of chemical heterogeneities ranging from about a couple of solute atoms to many tens of atoms (atomic clusters) may be formed without local changes in crystal structure. The mechanical properties of these alloys are strongly affected by the atomic scale clustering of solute atoms - whilst in this work we present some results for the corrosion properties (pitting propensity) of such alloys.
Development of High Strength and Highly Corrosion-Resistant Bulk Nanocrystalline Mg-Zn-Y Alloys with Long Period Stacking Ordered Phase
Authors: Yamasaki Michiaki , Izumi Shogo , Kawamura Yoshihito
Published: March 2009

Highly corrosion-resistant Mg97.25Zn0.75Y2 and Mg96.75Zn0.75Y2Al0.5 (at.%) alloys have been produced by the consolidation of rapidly solidified ribbons. Rapid solidification brought about the grain refinement and an increase in the solid solubility of Zn and Y into the Mg matrix, enhancing microstructural and electrochemical homogeneity, which in turn enhanced corrosion resistance. Passivation behavior was observed in dynamic anodic polarization measurements on rapidly solidified Mg-Zn-Y-Al alloy. The addition of Al to Mg might modify the structure of surface films and improve the resistance to local breakdown of the films.
Improvement of Barrier Anodic Oxide Al2O3 Passivation of Aluminum Alloy for LSI/FPD Plasma Process Equipment
Authors: Tahara Minoru , Kasase Yasuhiro , Kitano Masafumi , Mizutani Fumikazu , Shirai Yasuyuki , Ohmi Tadahiro
Published: March 2009

Barrier type anodic oxides film of the aluminum alloy in nonaqueous electrolyte solution has some excellent characteristics as a passivation film. In electrolyte that used the ethylene glycol as nonaqueous solution, the thickness of the anodic oxides film was able to be formed only up to about 0.3μm. However, the thickness of 0.5μm or more is demanded from the viewpoint of mechanical strength in actual manufacturing equipments. The barrier type anodic oxides film that exceeded 0.5μm was able to be formed by the use of a low dielectric constant glycol system solvent, the viscosity control of the electrolyte and other optimizations. The thick nonaqueous anodic oxides will be put to actual use as the passivation film for the plasma process equipment of the LSI/FPD manufacturing.
Hybridization of Polydiacetylene Core and Metal Shell
Authors: Onodera Tsunenobu , Ujita Junichi , Ishikawa Daisuke , Masuhara Akito , Kasai Hitoshi , Oikawa Hidetoshi
Published: March 2009

We have successfully fabricated hybridized nanoparticles composed of polydiacetylene nanocrystal (core) and Ag or Pt nanoparticle (shell) by means of visible-light-driven photocatalytic reduction. Difference in the reduction mechanism between Ag and Pt affected the size of deposited metal-nanoparticles. Next, the Ag-nanoparticles preformed on the polydicetylene nanocrystals were employed as both a catalyst and a substrate for an electroless plating. As a result, we succeeded in the fabrication of thicker Pt-shell and bimetal shell (Ag-Au, Ag-Pt, Ag-Pd). The core-shell-type nanoparticles were characterized using SEM, TEM, powder-XRD, EPMA and UV-Vis-NIR extinction spectroscopy.
Effects of Spatial and Spectral Characteristics of Electrons on Quantum Capacitance Oscillations in Silicon NanoWire-Based MOS Structure
Authors: Chin Sai Kong , Ligatchev Valeri
Published: March 2009

Capacitance-gate voltage [C(V)] characteristics of inversion layer of the cylindrical silicon nanowire (SiNW) MOS are simulated using a two-dimensional Schrödinger-Poisson (SP) self-consistent solver with explicit cylindrical coordinates and quantum-mechanical treatment within the effective mass approximation. Our simulation results demonstrate strong effects of confinement of electron wavefunctions on spatial and spectral characteristics of excess (inversion) electrons in SiNW-based MOS device, which eventually yield in significant oscillations in C(V) dependencies, simulated at temperatures below 40 K and SiNW radii below 8 nm.
Peroxidase Mimetic Activity at Tailored Nanocarbon Electrodes
Authors: Lyon Jennifer L L. , Stevenson Keith J.
Published: March 2009

We demonstrate here the intrinsic reactivity of nitrogen-doped carbon nanotubes (N-CNTs) toward H2O2 consumption and their use as a potential peroxidase mimetic. Analysis of N-CNT-modified glassy carbon electrodes in an rotating disk electrode (RDE) amperometry configuration indicates that the mechanism of H2O2 consumption is not a 2-electron reduction to H2O, as is observed for peroxidase-catalyzed H2O2 reduction. We believe that the N-CNT reaction mechanism toward H2O2 occurs through the decomposition of H2O2 to O2 and H2O, resulting in an increase in current at the N-CNT electrode as the newly generated H2O2 is electrochemically reduced. We have exploited this intrinsic reactivity by incorporating N-CNTs as a substitute for horseradish peroxidase (HRP) in a traditionally bi-enzymatic sensing scheme for the detection of glucose. These studies serve as proof of concept for the use of N-CNTs as a peroxidase mimetic in unmediated biogenic analyte detection.
Micro Reactor For Chlorophenols Electrocathalytic Oxidation
Authors: Radovici Octavian , Banu Alexandra , Pirvu C.
Published: March 2009

Chlorophenols are universal priority pollutants listed by all Environmental Agencies. The removal of chlorophenols from contaminated waters is carried out by microbiological and chemical methods. In this work is presented a combination of three methods that are electrochemical oxidation, electrochemical reduction and Photo Fenton oxidation. Results performed in a micropilot reactor showed that it is feasible to degrade Chlorophenols by these combined methods, with a removal rate of 82%, at a current density of 6.66 Adm-2. The current efficiency was calculated and the results indicated that this combined method is more efficient that separated ones (electrochemical oxidation or reduction).
Polypyrrole Modified Copper Electrode for Nitrate and Nitrite Reduction in Neutral Solutions
Authors: Phuong Thoa Nguyen Thi , Thinh Nguyen Viet , Hung Le Quoc
Published: March 2009

Conducting polypyrrole (Ppy) film was synthesized electrochemically onto a copper electrode in oxalate, oxalic acid and salicylic acid solutions. The electrochemical oxidation of pyrrole to form polypyrrole film and the electroreduction of nitrate and nitrite ions at synthesized PPy modified copper electrodes (Ppy/Cu) in potassium chloride aqueous solutions were studied by cyclic voltammetry. Polypyrrole film formation and the activity of the modified Ppy/Cu electrode for nitrate and nitrite reduction were found to be dependent on synthesis medium and conditions: pH, content and concentrations of the electrolytes; pyrrole concentration; electrode potential; electrolysis duration. The finishing and storage conditions of the prepared Ppy/Cu modified electrodes, such as drying duration and temperature; soaking duration in water before use, also affect their catalytic activity for nitrate and nitrite reduction. The highest reduction currents of nitrate and nitrite were obtained for the nanoporous structured Ppy film prepared in salicylic acid solution. Nitrate and nitrite reduction occurred at cathodic potentials of ca. -0.70 V and -0.85 V (Ag/AgCl) respectively, and the peak potentials ranged from -1.00 V to -1.15 V (Ag/AgCl). In the potassium chloride aqueous solution the reduction of nitrate and nitrite ions on the Ppy/Cu electrode was found irreversible.
Important Site of Luciferin on Firefly Bioluminescence
Authors: Maki Shojiro A.
Published: March 2009

The firefly bioluminescence is well known in the world. Although its emission efficiency is assumed the best of the earth, a color variation is aspired in top science. For producing color variation, we have innovated new technology by analyzing biofunctions.
Voltammetry of an Anti-cancer Drug
Authors: Haque Inam U. , Saba Hina
Published: March 2009

Voltammetric oxidation of vinblastine sulfate was studied at the platinum semi-micro electrode, by cyclic and pulsed voltammetric techniques, in 9:1 acetonitrile-water mixture containing 0.2 M sodium perchlorate. A plausible scheme of sequential electrochemical and chemical reactions is suggested for the cyclic voltammetric behavior of vinblastine.
Voltammetry of Nitrate at Solid Cathodes
Authors: Haque Inam U. , Tariq Muqaddas
Published: March 2009

In this work electrochemical kinetics of nitrate reduction was investigated on solid cathodes such as gold, titanium and aluminum. Enhancement of current density with increase in concentration of nitrate was observed with respect to the background in case of all electrode materials. The apparent electrochemical reaction order (14) for nitrate reduction was evaluated at various cathodes. The reaction order for the electro-reduction of nitrate at titanium showed dependence on electrode potential. Under the similar reactions conditions the electroreduction of nitrobenzene was also studied on the titanium electrode using cyclic voltammetry.
Critical Aspects of Chemical Etch Patterning of Magnetic Tunnel Junction-Based MRAM
Authors: O'Sullivan Eugene J. , Abraham David
Published: March 2009

This paper describes the development of a novel wet etch process for selective patterning of ferromagnetic freelayers in MRAM magnetic tunnel junction (MTJ) stacks. The method uses a nonadsorbing acid, trifluoromethane sulfonic (TFMSA), as the etchant acid. Freelayer etch selectivity to the alumina tunneling barrier is achieved through the use of long-chain alkane sulfonic acid salts, e.g. sodium 1-tetradecanesulfonate. These inhibitors can increase the alumina barrier etch resistance in the TFMSA solution by up to two orders of magnitude. Also discussed is a means of dramatically lowering lateral etching under the mask using an etch inhibitor.
Resistive-switching Solid-state Brain-neocortex-like Device for Advanced Non-volatile Logic Applications
Authors: Sasago Yoshitaka , Terao Motoyasu , Kinoshita Masaharu , Ono Kazuo , Kurotsuchi Kenzo , Takemura Riichiro , Fujisaki Yoshihisa , Takaura N.
Published: March 2009

A resistive-switching solid-state brain-neocortex-like device for advanced non-volatile logic applications was developed. This device can be used as a reconfigurable logic device that is operated by electrically connecting and disconnecting pairs of electrodes. This paper reports for the first time the experimental evaluation results of a three-terminal test element group as the unit for a solid state brain neocortex-like device. The solid-state brain-neocortex-like device was experimentally evaluated as unit in a three-terminal test element group. The evaluation results show that the neocortex-like reconfigurable switching, in particular, fringe-electric-field-induced switching is possible in the device.
Impedance Spectroscopy of Resistance Switching CaCu3Ti4O12 Films Derived by Sol-Gel Process
Authors: Shen Yu-Shu , Ho Chia-Cheng , Chiou Bi-Shiou
Published: March 2009

A novel material CaCu3Ti4O12 (CCTO), for resistance random access memory (RRAM) application, was prepared by sol-gel method. Our preliminary study indicates CCTO shows the resistive switching behaviors of RRAM. In this work, the resistance switching characteristics of CCTO films are investigated. The dielectric properties of CCTO films were observed by the impedance spectroscopy. On the basis of the results observed by impedance spectroscopy, the conduction mechanisms of the CCTO RRAMs at the original state, ON state, and OFF state are explored.
Printed Organic Memory Devices
Authors: Lian Keryn K. , Zhang Jie , Li Rohphina , Wang Hui , Hsi Wayne
Published: March 2009

A novel, low cost organic data storage system was investigated. The device demonstrated electrical field induced switching and bistable characteristics, and can be used as non-volatile memory. The material stack consisted of top and bottom electrodes, an organic active layer, and a conductive polymer interface layer sandwiched in between the electrodes. The active materials are solution-based and can be readily deposited via graphic arts printing processes. This technology enables switching and memory capabilities for large area flexible electronics using solution deposition processes and low cost solution based materials.
Catalytic Current Based on Direct Electron Transfer Reactions of Enzymes Immobilized onto Carbon Nanotubes
Authors: Tominaga Masato , Kaneko Shiori , Nomura Shinya , Sakamoto Shingo , Yamaguchi Hiroyuki , Nishimura Toshifumi , Taniguchi Isao
Published: March 2009

Multi-walled and single-walled carbon nanotubes were synthesized on platinum plate (MWCNTs/pt) and gold wire (SWCNTs/Au) electrodes, respectively, using a chemical vapor deposition (CVD) method. These carbon nanotube-modified electrodes were immersed into solutions of glucose oxidase (GOX) and D-fructose dehydrogenase (FDH) to immobilize these enzymes onto the electrode surfaces. After GOX was immobilized onto the MWCNT/Pt electrode, the well-defined catalytic oxidation current was increased from ca. -0.45 V (vs. Ag/AgCl/saturated KCl), which was close to the redox potential of flavin adenine dinucleotide as a prosthetic group of GOX under physiological pH values. Furthermore, catalytic oxidation currents of fructose based on direct heterogeneous electron transfer reactions between FDH and the SWCNT/Pt electrode were observed.
A High-Power Glucose/Oxygen Biofuel Cell Operating under Quiescent Conditions
Authors: Sakai Hideki , Nakagawa Takaaki , Mita Hiroki , Matsumoto Ryuhei , Sugiyama Taiki , Kumita Hideyuki , Tokita Yuichi , Hatazawa Tsuyonobu
Published: March 2009

We have developed the passive-type biofuel cell, in which two-electron oxidation of glucose and four-electron reduction of O2 occur at pH 7 in mediated bioelectrochemical processes, having the maximum power density of 5.0 mW/cm2 at 500 mV. This performance has been achieved by using a new electrolyte solution (Imidazole/HCl buffer, 2 M, pH 7), instead of the general solution (Sodium phosphate buffer, 1 M, pH 7); the maximum power density was a 3.0 mW/cm2 at the same conditions. By introducing the new electrolyte solution into our biofuel cell, we have succeeded in enhancing the catalytic current because the proton transfer into electrodes would increase compared with the phosphate buffer system.
Effect of Electrochemically Structured Titanium Alloys on Cell Morphology
Authors: Roy S. , Wu Qi-Bai , Nouraei S. , Ngalim S. , Birch M. , McCaskie A. , Zhang H. , Osaka Tetsuya
Published: March 2009

Ti alloys are commonly used as dental and orthopaedic implants. It has been shown that surface topography can influence cell genesis, behaviour and growth. In this work we have electropolished and micro-patterned Ti-6Al-4V alloy to study the effect of surface topography on cell morphology. Electroetching was carried out in a flat cell under galvanostatic polarisation of 5.0 V and 9.0 V vs. SCE, using a 3.0 M H2SO4 - methanol electrolyte. Electropolishing conditions were achieved when the overpotential was 9.0 V. Micropatterning of Ti alloy substrates was carried out at the same potentials by etching through mask; a methanol stable SU-8 photoresist was used for this purpose. Human mesenchymal stem cells were seeded and grown on these substrates. It was found that surface nano and micro scale topography influenced cell numbers and morphology, respectively.
Preparation of HA/Al2O3 Functionally Gradient Coating on Titanium Substrate Using a Combination of Electrophoretic Deposition and Reaction Bonding Process
Authors: Wang Zhou-Cheng , Ni Yong-Jin
Published: March 2009

The major difficulty in fabricating hydroxyapatite (HA) coatings on titanium substrate using the electrophoretic deposition (EPD) process is the full densification and crack prevention of the coating under the restricted sintering temperature. First, HA/aluminum oxide composite coatings were fabricated on titanium substrate using the combination of electrophoretic deposition and reaction bonding process. Results show that the reaction bonding process enhances the coating's densification degree and significantly increase its bonding strength. Then, HA/Al2O3 functionally gradient coating (FGC) were also fabricated on titanium. Results show that, the preparation of FGC prevents cracking of the coating with a thickness about 35um. Chemical composition and microstructure of the HA/Al2O3 FGC exhibit obvious gradient variation. The HA/Al2O3 FGC also exhibits much higher bonding strength than that of HA coating with the same thickness.
The Forms of The Law of Dilution for Weak Multibasic Organic Acids in Case of Overlapping Equilibria
Authors: Kvaratskhelia Elene , Kvaratskhelia Ramaz
Published: March 2009

The original equations of the laws of dilution for weak tri-, tetra-, penta- and hexabasic organic acids with the close values of the dissociation constants of various steps are suggested. The methods for the calculation of the values of the degrees of dissociation are described.
Detection of DNA π-Stack Lesions Using Scanning Electrochemical Microscopy
Authors: Hammond William , Arndt Justin , Nguyen Thi , Slowinska Katarzyna , Jackson Christopher , Burgoyne Hayden , Hill Michael , Slowinski Krzysztof
Published: March 2009

The Scanning electrochemical microscopy (SECM) is used to selectively detect intervening mismatches and abasic sites within monolayers of ds-DNA self-assembled onto gold electrodes. The electrocatalytic cycle involving oxidation of leucomethylene blue (LB), an electrochemically reduced form of methylene blue intercalated within the ds-DNA monolayer self-assembled on gold electrode, by the SECM tip-generated ferricyanide allows regeneration of LB via long-range heterogenous electron transfer mediated by the DNA π-stack. Monolayers featuring disruptions in the DNA π-stack via a single-base mismatch or abasic site exhibit strongly attenuated methylene blue electrochemistry within the DNA film leading to a disruption of the catalytic cycle, thereby diminishing the SECM tip current. The inherent differences in catalytic tip currents can be used to distinguish monolayer domains containing native ds-DNA versus ds-DNA containing π-stack lesions within the micron-level lateral spatial resolution of SECM.