bluuebunny/crossref_metadata_2025 huggingface dataset:
An Overview of Modeling and Simulation of the Milling Process
Authors: Smith S. , Tlusty J.
Published: April 2010

In this paper, various models of the milling process in frequent use are reviewed. They are classified in order of increasing sophistication and accuracy as (1) the Average Rigid Force Static Deflection Model, (2) the Instantaneous Rigid Force Model, (3) the Instantaneous Rigid Force, Static Deflection Model, (4) the Instantaneous Force With Static Deflection Feedback Model, and (5) the Regenerative Force, Dynamic Deflection Model. In each case, the validity, possible applications, and limitations of the model are discussed. In the final section, several applications of the Regenerative Force, Dynamic Deflection Model are used to illustrate the wide range of applicability of this model.
Mechanics of Bar Straightening, Part 1: General Analysis of Straightening Process
Authors: Das Talukder N. K. , Singh A. N.
Published: April 2010

In the following paper, a general analysis of the mechanics involved in the straightening process of bars and sections by reverse kinematic loading has been made.
Feasible and Optimal Designs of Variable Air Gap Torque Motors
Authors: Leu M. C. , Aubrecht R. A.
Published: April 2010

The problems of automating the feasible and optimal designs of variable air gap torque motors are studied. Both are formulated as constrained optimization problems, where equality and inequality constraints are associated with the geometrical and physical characteristics of the device. Numerical results show that feasible designs can be obtained for specified rated torque outputs, and optimal designs can be achieved by reducing the volume or power consumption substantially from the initial designs, without reducing the rated torque output.
CFD Simulation of the Bubbling and Slugging Gas-Solid Fluidized Beds
Authors: Hosseini Seyyed Hossein , Zhong Wenqi , Esfahany Mohsen Nasr , Pourjafar Leila , Azizi Salar
Published: April 2010

A two-dimensional transient Eulerian model integrating the kinetic theory for emulsion phase is used to simulate the bubbling and slugging gas-solid fluidized beds, including the Geldart B and D particles, respectively. CFD results show that utilizing an algebraic granular temperature equation, instead of a full granular temperature, one leads to a significant reduction in computational time without loosing accuracy. Different drag models have been examined in the current study. CFD results show that the Syamlal–O’Brien and Di Felice adjusted drag models, based on minimum fluidization velocity, are not suitable for the bed, including coarse particles (Geldart group B). The Gidaspow drag model displays better results in comparison with the others. A good agreement with the available experimental data and the researcher’s findings has been reached quantitatively and qualitatively. The proposed model can reasonably be used for simulation of slugging fluidized beds. This study reduces the computational error compared with the previous works.
Implicit LES Predictions of the Cavitating Flow on a Propeller
Authors: Bensow Rickard E. , Bark Göran
Published: April 2010

We describe an approach to simulate dynamic cavitation behavior based on large eddy simulation of the governing flow, using an implicit approach for the subgrid terms together with a wall model and a single fluid, two-phase mixture description of the cavitation combined with a finite rate mass transfer model. The pressure-velocity coupling is handled using a PISO algorithm with a modified pressure equation for improved stability when the mass transfer terms are active. The computational model is first applied to a propeller flow in homogeneous inflow in both wetted and cavitating conditions and then tested in an artificial wake condition yielding a dynamic cavitation behavior. Although the predicted cavity extent shows discrepancy with the experimental data, the most important cavitation mechanisms are present in the simulation, including internal jets and leading edge desinence. Based on the ability of the model to predict these mechanisms, we believe that numerical assessment of the risk of cavitation nuisance, such as erosion or noise, is tangible in the near future.
Effects of focused MeV ion beam irradiation on the roughness of electrochemically micromachined silicon surfaces
Authors: Ow Y. S. , Azimi S. , Breese M. B. H. , Teo E. J. , Mangaiyarkarasi D.
Published: April 2010

The authors compare the effects of focused and broad MeV ion beam irradiation on the surface roughness of silicon wafers after subsequent electrochemical anodization. With a focused beam, the roughness increases rapidly for low fluences and then slowly decreases for higher fluences, in contrast to broad beam irradiation where the roughness slowly increases with fluence. This effect is important as it imposes a limitation on the ability to fabricate smooth surfaces using focused ion beam irradiation. For a given fluence, small variations in the resistivity of an irradiated area may arise due to fluctuations of the focused beam current during irradiation. These small variations in resistivity then give rise to an increased roughness during the electrochemical etching. The roughness may be reduced by increasing the scan speed, which alters the way in which the fluctuations in fluence are averaged out over the irradiated surface.
Cesium and oxygen activated amorphous silicon germanium photocathodes for photoinjectors
Authors: Mulhollan G. A. , Bierman J. C.
Published: April 2010

Amorphous silicon and amorphous silicon germanium photoemitters grown via radio frequency plasma enhanced chemical vapor deposition have been investigated to determine their usefulness as photoinjector electron sources. Characterized properties include activation process, wavelength dependent photoyield, germanium induced photoyield shift, background gas and ion sensitivities, and average transverse emission energy. While overall lower in yield than the GaAs photoemitter, many of their properties are comparable. The amorphous silicon photoemitter robustness upon gas and ion exposure is superior to that of GaAs. The combined properties of amorphous silicon germanium photoemitters make them ideal candidates for low cost photoinjector sources or as protective photoemitting layers on more sensitive photogenerating materials.
A Hot Channel
Authors: Adler Elizabeth M.
Published: April 2010

Snakes sense infrared radiation through the temperature-dependent activation of the TRPA1 ion channel.
TRIM Proteins: Another Class of Viral Victims
Authors: Munir Muhammad
Published: April 2010

Influenza A virus suppresses the host interferon response by interfering with the RIG-I and TRIM25 antiviral molecules.
Science Signaling
Podcast: 20 April 2010
Authors: Berger Seth I. , Iyengar Ravi , VanHook Annalisa M.
Published: April 2010

Integrating interactome and genetics data allows researchers to predict adverse drug effects.
Exploratory Study of the Prevalence and Clinical Significance of Tobramycin-Mediated Biofilm Induction in
Pseudomonas aeruginosa
Isolates from Cystic Fibrosis Patients
Authors: Elliott Danielle , Burns Jane L. , Hoffman Lucas R.
Published: April 2010

Exposure to aminoglycoside antibiotics induces biofilm formation by a laboratory strain of the cystic fibrosis (CF) pathogen
Pseudomonas aeruginosa
. Here, we detected this effect among about half of the clinical isolates from CF patients in a cross-sectional collection, suggesting that biofilm induction may represent a common mechanism of inducible aminoglycoside resistance in CF infections. This induction always occurred at the same tobramycin concentration regardless of MIC, suggesting that the mechanisms of killing and induction may be separable.
Plasmodium falciparum
Isolates with Increased
pfmdr1
Copy Number Circulate in West Africa
Authors: Witkowski Benoit , Nicolau Marie-Laure , Soh Patrice Njomnang , Iriart Xavier , Menard Sandie , Alvarez Muriel , Marchou Bruno , Magnaval Jean-François , Benoit-Vical Françoise , Berry Antoine
Published: April 2010

Amplification of
pfmdr1
in
Plasmodium falciparum
is linked to resistance to aryl-amino-alcohols and in reduced susceptibility to artemisinins. We demonstrate here that duplicated
pfmdr1
genotypes circulate in West Africa. The monitoring of this prevalence in Africa appears essential for determining the antimalarial policy and to maintain the efficiency of artemisinin-based combination therapy (ACT) for as long as possible.
In Vitro
Activity of Ceftaroline against Community-Associated Methicillin-Resistant, Vancomycin-Intermediate, Vancomycin-Resistant, and Daptomycin-Nonsusceptible
Staphylococcus aureus
Isolates
Authors: Saravolatz Louis , Pawlak Joan , Johnson Leonard
Published: April 2010

This study assessed the
in vitro
activities of ceftaroline and five comparator agents against a collection of
Staphylococcus aureus
isolates. Ceftaroline demonstrated potent activity against community-associated methicillin-resistant
S. aureus
(CA-MRSA) isolates and showed bactericidal activity against vancomycin-intermediate
S. aureus
(VISA), vancomycin-resistant
S. aureus
(VRSA), heteroresistant VISA (hVISA), and daptomycin-nonsusceptible
S. aureus
(DNSSA) isolates. Ceftaroline may represent a bactericidal treatment option for infections caused by these pathogens.
Severity of
Staphylococcus aureus
Infection of the Skin Is Associated with Inducibility of Human β-Defensin 3 but Not Human β-Defensin 2
Authors: Zanger Philipp , Holzer Johannes , Schleucher Regina , Scherbaum Helmut , Schittek Birgit , Gabrysch Sabine
Published: April 2010

Gram-positive bacteria are the predominant cause of skin infections. Antimicrobial peptides (AMPs) are believed to be of major importance in skin's innate defense against these pathogens. This study aimed at providing clinical evidence for the contribution of AMP inducibility to determining the severity of Gram-positive skin infection. Using real-time PCR, we determined the induction of human β-defensin 2 (HBD-2), HBD-3, and RNase 7 by comparing healthy and lesional mRNA levels in 32 patients with Gram-positive skin infection. We then examined whether AMP induction differed by disease severity, as measured by number of recurrences and need for surgical drainage in patients with
Staphylococcus aureus
-positive lesions. We found that HBD-2 and -3, but not RNase 7, mRNA expression was highly induced by Gram-positive bacterial infection in otherwise healthy skin. Less induction of HBD-3, but not HBD-2, was associated with more-severe
S. aureus
skin infection: HBD-3 mRNA levels were 11.4 times lower in patients with more than 6 recurrences (
P
= 0.01) and 8.8 times lower in patients reporting surgical drainage (
P
= 0.01) than in the respective baseline groups. This suggests that inducibility of HBD-3 influences the severity of Gram-positive skin infection
in vivo
. The physiological function of HBD-2 induction in this context remains unclear.
Dendritic Cells Inhibit the Progression ofListeria monocytogenesIntracellular Infection by Retaining Bacteria in Major Histocompatibility Complex Class II-Rich Phagosomes and by Limiting Cytosolic Growth
Authors: Westcott Marlena M. , Henry Curtis J. , Amis Jacqueline E. , Hiltbold Elizabeth M.
Published: April 2010

Dendritic cells (DC) provide a suboptimal niche for the growth ofListeria monocytogenes, a facultative intracellular bacterial pathogen of immunocompromised and pregnant hosts. This is due in part to a failure of large numbers of bacteria to escape to the cytosol, an essential step in the intracellular life cycle that is mediated by listeriolysin O (LLO). Here, we demonstrate that wild-type bacteria that failed to enter the cytosol of bone marrow-derived DC were retained in a LAMP2+compartment. An isogenicL. monocytogenesstrain that produces an LLO protein with reduced pore-forming activity had a severe escape and growth phenotype in DC. Few mutant bacteria entered the cytosol in the first 2 h and were instead found in LAMP2+, major histocompatibility complex class II+(MHC-II+) H2-DM vesicles characteristic of MHC-II antigen loading compartments (MIIC). In contrast, the mutant had a minor phenotype in bone marrow-derived macrophages (BMM) despite the reduced LLO activity. In the first hour, DC phagosomes acidified to a pH that was, on average, half a point higher than that of BMM phagosomes. Unlike BMM,L. monocytogenesgrowth in DC was minimal after 5 h, and consequently, DC remained viable and matured late in infection. Taken together, the data are consistent with a model in which phagosomal maturation events associated with the acquisition of MHC-II molecules present a suboptimal environment forL. monocytogenesescape to the DC cytosol, possibly by limiting the activity of LLO. This, in combination with an undefined mechanism that controls bacterial growth late in infection, promotes DC survival during the critical maturation response.
Rotary powered device for bone marrow aspiration and biopsy yields excellent specimens quickly and efficiently
Authors: Swords Ronan T , Kelly Kevin R , Cohen Stephen C , Miller Larry J , Philbeck Thomas E , Hacker Sander O , Spadaccini Cathy J , Giles Francis J , Brenner Andrew J
Published: April 2010

Recently, a new FDA-cleared battery powered bone marrow biopsy system was developed to allow operators access to the bone marrow space quickly and efficiently. A pre-clinical evaluation of the device (OnControl, Vidacare Corporation, San Antonio, TX, USA) on anesthetized pigs was conducted, in addition to a clinical evaluation in hematology clinic patients requiring a bone marrow biopsy. Twenty-six samples were collected from the swine model. No cellular artifact or thermal damage was reported in any of the samples obtained. For the clinical evaluation of the device, 16 patients were recruited. Mean time from needle contact with skin to needle removal was 38.5 +/− 13.94 seconds. No complications were reported. In this study, the manual and powered samples were equivalent in specimen quality. In the patients evaluated, the device was safe, easy to use and the mean procedural time was significantly faster than previously reported with a manual technique.
HIERARCHICAL MODELING OF THERMOELASTIC PLATES WITH VARIABLE THICKNESS
Authors: AVALISHVILI G. , AVALISHVILI M. , GORDEZIANI D. , MIARA B.
Published: April 2010

The present paper is devoted to the construction and investigation of hierarchies of two-dimensional models for thermoelastic plates with variable thickness which may vanish on some part of the boundary. The hierarchical models are obtained by a semidiscretization of the three-dimensional problem in the transverse direction of plate. In suitable weighted Sobolev spaces, we prove existence and uniqueness of solutions of the initial-boundary value problems corresponding to the obtained two-dimensional models of thermoelastic plate with variable thickness. Moreover, we prove convergence in the corresponding spaces of the sequence of approximate solutions restored from the solutions of the reduced problems to the solution of the original three-dimensional problem and estimate the rate of convergence.
CROSS-VALIDATION BASED ADAPTATION FOR REGULARIZATION OPERATORS IN LEARNING THEORY
Authors: CAPONNETTO ANDREA , YAO YUAN
Published: April 2010

We consider learning algorithms induced by regularization methods in the regression setting. We show that previously obtained error bounds for these algorithms, using a priori choices of the regularization parameter, can be attained using a suitable a posteriori choice based on cross-validation. In particular, these results prove adaptation of the rate of convergence of the estimators to the minimax rate induced by the "effective dimension" of the problem. We also show universal consistency for this broad class of methods which includes regularized least-squares, truncated SVD, Landweber iteration and ν-method.
SPIN WAVES TRANSMISSION VIA A MOLECULAR JUNCTION CONNECTING TWO QUASI-2D HEISENBERG FERROMAGNETS
Authors: BELHADI M. , AIDER N. , KHATER A.
Published: April 2010

A theoretical investigation of spin wave dynamics and scattering at a molecular junction between two Heisenberg ferromagnets is presented. The model system consists of two ferromagnetic ultrathin films with equal thickness of three atomic layers, joined together by a magnetic molecule. No electronic effects are considered, but local changes in the magnetic exchange field are assumed to be dominant. The mathematical framework of the matching method is used with nearest neighbor magnetic exchange interactions, to analyze both the spin fluctuation dynamics and the spin wave scattering phenomena at the junction boundary. The coherent reflection and transmission probabilities and the conductance of spin waves incident from the interior of the films onto the boundary are calculated in accordance with the Landauer–Büttiker formalism, and numerical results are presented for representative sets of system parameters for a large range of scattering frequencies. The scattered spectra show interesting sharp features, with associated Fano resonances, as a function of scattering frequencies, system parameters, and spin wave incidence angle. Moreover, a frequency selective conductance of the spin waves via Fano resonances can be obtained by an appropriate choice of the spin wave incident angle and system parameters.
CONTROLLED GROWTH OF ISOLATED VANADIUM NANOSTRUCTURES VIA PULSED LASER ABLATION
Authors: PHILLIPS A. B. , SHIVARAM B. S.
Published: April 2010

Utilizing pulsed laser ablation we show that it is possible to grow isolated nanostructures of vanadium whose shape and size are controllable simply by changing the background pressure of an inert gas in the growth chamber. The nanostructures obtained are characterized through scanning electron microscopy measurements. The range of nanostructures obtained by a simple one parameter control suggest that further synthesis of more sophisticated nanoscale composite structures should be possible if multistep growth and processing are employed.
SYNTHESIS AND CHARACTERIZATION OF CdTe NANOPARTICLES EMBEDDED IN NOVEL GLASS MATRIX
Authors: WAGEH S. , HIGAZY A. A. , KHAFAGY A. H. , EID A. S.
Published: April 2010

A study of the growth of CdTe nanoparticles in novel glass system was presented. The effect of the growth of CdTe nanocrystals on the glass structure was been investigated by different techniques: differential thermal analysis (DTA), X-ray diffraction (XRD) analysis, and optical absorption spectra and FTIR spectroscopy. The evolution of X-ray diffraction at different annealing temperatures is studied and showed that the ratios of the elemental of semiconductor constituents decrease with increasing annealing temperatures. Furthermore X-ray analysis showed that the sizes of the nanoparticles increase with increasing annealing temperatures. The investigation of the absorption spectra and calculation of nanoparticles sizes from the first absorption maximum are very close to the sizes calculated by Sherrer equation. Finally, FTIR spectroscopy explained the exchangeable effects between the glass matrix and semiconductor nanoparticles during the growth of nanoparticles.
ROAD NETWORKS WITH PHASE TRANSITIONS
Authors: COLOMBO RINALDO M. , GOATIN PAOLA , PICCOLI BENEDETTO
Published: April 2010

This paper is devoted to a hyperbolic 2-phase model for traffic flow on a network. The model is rigorously described and the existence of solutions is proved, without any restriction on the network geometry.
GLOBAL CONTINUOUS SOLUTIONS FOR DIAGONAL HYPERBOLIC SYSTEMS WITH LARGE AND MONOTONE DATA
Authors: EL HAJJ AHMAD , MONNEAU RÉGIS
Published: April 2010

In this paper, we study diagonal hyperbolic systems in one space dimension. Based on a new gradient entropy estimate, we prove the global existence of a continuous solution, for large and non-decreasing initial data. We remark that these results cover the case of systems which are hyperbolic but not strictly hyperbolic. Physically, this kind of diagonal hyperbolic system appears naturally in the modeling of the dynamics of dislocation densities.
SCALAR CONSERVATION LAWS ON A HALF-LINE: A PARABOLIC APPROACH
Authors: BANK MIRIAM , BEN-ARTZI MATANIA
Published: April 2010

The initial-boundary value problem for the (viscous) nonlinear scalar conservation law is considered, [Formula: see text] The flux f(ξ) ∈ C2(ℝ) is assumed to be convex (but not strictly convex, i.e. f″(ξ)≥ 0). It is shown that a unique limit u = lim∊ → 0u∊exists. The classical duality method is used to prove uniqueness. To this end parabolic estimates for both the direct and dual solutions are obtained. In particular, no use is made of the Kružkov entropy considerations.
AN IMPLICIT COVER PROBLEM IN WILD POPULATION STUDY
Authors: ASHLEY MARY V. , BERGER-WOLF TANYA Y. , CHAOVALITWONGSE WANPRACHA , DASGUPTA BHASKAR , KHOKHAR ASHFAQ , SHEIKH SAAD
Published: April 2010

In an implicit combinatorial optimization problem, the constraints are not enumerated explicitly but rather stated implicitly through equations, other constraints or auxiliary algorithms. An important subclass of such problems is the implicit set cover (or, equivalently, hitting set) problem in which the sets are not given explicitly but rather defined implicitly. For example, the well-known minimum feedback arc set problem is such a problem. In this paper, we consider such a cover problem that arises in the study of wild populations in biology in which the sets are defined implicitly via the Mendelian constraints and prove approximability results for this problem.
POSI-MODULAR SYSTEMS WITH MODULOTONE REQUIREMENTS UNDER PERMUTATION CONSTRAINTS
Authors: ISHII TOSHIMASA , MAKINO KAZUHISA
Published: April 2010

Given a system (V, f, r) on a finite set V consisting of a posi-modular function f : 2V → ℝ and a modulotone function r : 2V → ℝ, we consider the problem of finding a minimum set R ⊆ V such that f(X) ≥ r(X) for all X ⊆ V - R. The problem, called the transversal problem, was introduced in [M. Sakashita, K. Makino, H. Nagamochi and S. Fujishige, Minimum transversals in posi-modular systems, SIAM J. Discrete Math.23 (2009) 858–871] as a natural generalization of the source location problem and external network problem with edge-connectivity requirements in undirected graphs and hypergraphs.

By generalizing [H. Tamura, H. Sugawara, M. Sengoku and S. Shinoda, Plural cover problem on undirected flow networks, IEICE Trans.J81-A (1998) 863–869] for the source location problem, we show that the transversal problem can be solved by a simple greedy algorithm if r is π-monotone, where a modulotone function r is π-monotone if there exists a permutation π of V such that the function pr: V × 2V → ℝ associated with r satisfies pr(u, W) ≥ pr(v, W) for all W ⊆ V and u, v ∈ V with π(u) ≥ π(v). Here we show that any modulotone function r can be characterized by pr as r(X) = max {pr(v, W) | v ∈ X ⊆ V - W}.

We also show the structural properties on the minimal deficient sets [Formula: see text] for the transversal problem for π-monotone function r, i.e., there exists a basic tree T for [Formula: see text] such that π(u) ≤ π(v) for all arcs (u,v) in T, which, as a corollary, gives an alternative proof for the correctness of the greedy algorithm for the source location problem.

Furthermore, we show that a fractional version of the transversal problem can be solved by the algorithm similar to the one for the transversal problem.
ASYMPTOTIC DISTRIBUTION OF THE NUMBER OF ISOLATED NODES IN WIRELESS AD HOC NETWORKS WITH UNRELIABLE NODES AND LINKS
Authors: YI CHIH-WEI , WAN PENG-JUN , SU CHAO-MIN , LIN KUO-WEI , HUANG SCOTT C.-H.
Published: April 2010

In this paper, we study the connectivity of wireless ad hoc networks that are composed of unreliable nodes and links by investigating the distribution of the number of isolated nodes. We assume that a wireless ad hoc network consists of n nodes distributed independently and uniformly in a unit-area disk or square. All nodes have the same maximum transmission radius rn, and two nodes have a link if their distance is at most rn. Nodes are active independently with probability 0 < p1 ≤ 1, and links are up independently with probability 0 < p2 ≤ 1. Nodes are said isolated if they do not have any links to active nodes. We show that if [Formula: see text] for some constant ξ, then the total number of isolated nodes (or isolated active nodes, respectively) is asymptotically Poisson with mean e-ξ (or p1e-ξ, respectively). In addition, in the secure wireless networks that adopt m-composite key predistribution schemes, a node is said isolated if it does not have a secure link. Let p denote the probability of the event that two neighbor nodes have a secure link. If all nodes have the same maximum transmission radius [Formula: see text], the total number of isolated nodes is asymptotically Poisson with mean e-ξ.
Study of Structural and Electrical Properties of Phosphorus-Doped p-Type ZnO Thin Films
Authors: Wang Yipeng , Zhou Jianqing , Lu Qian , Liu Lilong , Zhang Xin , Wu Xiaojing
Published: April 2010

Phosphorus-doped ZnO thin films were fabricated by pulsed laser deposition (PLD) with different phosphorus pentoxide (P2O5) concentrations. The as-deposited films were annealed in nitrogen gas at 800 °C for 5 min. Hall effect measurement showed that all the as-deposited films were n-type semiconductors, and confirmed that after annealing treatment, a particular sample could be transformed from an n-type semiconductor into a p-type one. On the basis of the results of X-ray diffraction analysis and X-ray photoelectron spectroscopy, the mechanism of such transformation was discussed.
Large Remanent Polarization in Sm-Substituted BiFeO3 Thin Film Formed by Chemical Solution Deposition
Authors: Zhong Zhiyong , Sugiyama Yoshihiro , Ishiwara Hiroshi
Published: April 2010

Bi1-x
Sm
x
FeO3 (x=0–0.15) (BSFO) thin films were formed on Pt/Ti/SiO2/Si(100) substrates by chemical solution deposition. The spin-coated, dried, and prefired thin films were finally crystallized at 500 °C in air and in N2. It was found that Sm-substitution for Bi in BiFeO3 increased the grain size and the leakage current density. The optimal concentration for improving remanent polarization (P
r) was characterized to be 5 at. %. In 10 and 15 at. % BSFO films, incorporation of Sm atoms was found to be excess, leading to degradation of ferroelectric properties. The P
r and coercive electric field values in 5 at. % BSFO film measured at electric field of 1.5 MV/cm and frequency of 25 kHz were 82 µC/cm2 and 0.35 MV/cm, respectively. In addition, the minimal coercive electric voltage of 7.5 V was achieved in a 126-nm-thick 7.5 at. % Sm-substituted BFO film.
Measurement of Nonlinear Current–Voltage Dependence of Interfacial Passive Layers for Ferroelectric Thin Films
Authors: Chen Zhi Hui , Shen Zhen Kui , Jiang An Quan
Published: April 2010

Theoretically, interfacial passive layers identified in most ferroelectric thin films are assumed to be highly insulating to tilt polarization–voltage (P–V) hysteresis loops and to reduce the apparent coercive field. Practically, the layers would be leaky under an extremely high field, where the P–V loop remains squared rather than tilted. In this work, we develop a technique to measure the nonlinear current–voltage dependence across the interfacial layers during domain switching. With the aid of this technique, we simulate the interfacial current–voltage relationship by using conventional conduction models. After elimination of the interfacial-layer effect on the coercive-voltage estimation with different film thicknesses, we extract domain switching current dependence of the intrinsic coercive field, irrespective of the film thickness. The thermal activation field derived from domain switching model of the Merz's law is around 1.4 kV/cm, unexpectedly smaller than those in bulk ceramics.
Effects of Hafnium Substitution on Dielectric and Electromechanical Properties of Lead-free Bi0.5(Na0.78K0.22)0.5(Ti1-xHfx)O3Ceramics
Authors: Hussain Ali , Ahn Chang Won , Ullah Aman , Lee Jae Shin , Kim Ill Won
Published: April 2010

Lead-free piezoelectric Bi0.5(Na0.78K0.22)0.5(Ti1-xHfx)O3ceramics (abbreviated as BNKTH-100x,x=0–0.05) were prepared by the conventional solid-state reaction method. The effects of Hf substitution on the crystal structure and electromechanical properties were investigated. The X-ray diffraction patterns of the BNKTH-100xceramics revealed a single-phase perovskite structure with no evidence of secondary phases. The temperature-dependent dielectric curves of the BNKTH-100xceramics were found to broaden with increasing Hf concentration. The electric-field-induced strain of the BNKTH-100xceramics increased up tox=0.03 and then decreased. An enhanced electric-field-induced strain of 0.38% is observed for the BNKTH-3 ceramic. The corresponding normalized strain (Smax/Emax=d33*) for this composition was 475 pm/V at an applied electric field of 80 kV/cm. The BNKTH-3 ceramic can be considered as a promising candidate material for lead-free electromechanical applications.
Mechanism Underlying Stacking-Layer Effect of Dielectric Properties of Multilayer Ceramic Capacitors
Authors: Yokomizo Satoshi , Hoshina Takuya , Takeda Hiroaki , Taniguchi Katsuya , Mizuno Youichi , Chazono Hirokazu , Tsurumi Takaaki
Published: April 2010

The stacking-layer effect in multilayer ceramic capacitors (MLCCs) is a phenomenon in which the dielectric permittivity of dielectric layers increases with increasing number of layers. To elucidate the mechanism underlying this effect, we performed a simulation of residual stress in MLCCs by the finite element method (FEM) as well as dielectric measurements under uniaxial compressive stress. The FEM analysis revealed that tensile stress along the stacking direction was induced in dielectric layers owing to the difference in thermal expansion coefficient between internal electrodes and dielectric layers. The results of dielectric measurements indicated that the shell part in the dielectrics of MLCCs played an important role in the stress dependence of dielectric properties. The mechanism underlying the stacking-layer effect proposed in this study was based on the enhancement of polarization rotations in polar nanoregions in the relaxor by the tensile stress in dielectric layers.
Wide Band Dielectric Spectroscopy at Ferroelectric Phase Transition of BaTiO3 Ceramics
Authors: Teranishi Takashi , Hoshina Takuya , Takeda Hiroaki , Tsurumi Takaaki
Published: April 2010

Ultrawide band dielectric spectra from kHz to THz were measured to investigate quantitatively the contributions of ionic and dipole polarizations to the ferroelectric phase transition in BaTiO3 (BT) ceramics. Permittivity derived from ionic polarization (ε
ionic) exhibited its maximum at the Curie temperature (T
c), attributing to the softening of the soft phonon mode. Permittivity derived from dipole polarization (ε
dipole) was nearly constant below the T
c, while ε
dipole remained above the T
c and ε
dipole increased on cooling, exhibiting its maximum near the T
c. The behavior in ε
dipole above the T
c could be interpreted as precursor phenomenon of ferroelectric phase transition and the ε
dipole above the T
c was due to the local tetragonal type distortion in paraelectric phase.
Electrochemical Oscillation in Electrohydrodynamic Fluid
Authors: Abe Hiroshi , Imai Yusuke , Michishita Yosuke , Yamashita Yasuhiro , Sasaki Yoshiki
Published: April 2010

We found that electrohydrodynamic (EHD) pressure is affected by a combination of surface conditions and shape of electrodes. A smooth surface of electrodes can generate a higher pressure in the low-current region. Under ac electric fields, rhythmic electrochemical oscillation of current is induced in the dielectric liquid C4F9OCH3. From the ac frequency dependence of rhythmic current, two types of relaxation time appeared. The relaxation times correspond to the Helmholtz layer and diffuse layer, which are regarded as an electric double layer. In the case of pressure as a function of ac frequency, a stable, high pressure was obtained using a smooth surface above the relaxation frequency of the diffuse layer.
Light Extraction Enhancement of GaN-Based Light-Emitting Diodes Using Volcano-Shaped Patterned Sapphire Substrates
Authors: Kim Jae Bum , Kim Sang-Mook , Kim Young Woo , Kang Sung-Ku , Jeon Seong-Ran , Hwang Nam , Choi Yeon-Jo , Chung Chang Sub
Published: April 2010

A new volcano-shaped patterned sapphire substrate (VPSS), which enhances the light extraction efficiency (LEE) of GaN-based light emitting diodes (LEDs), was presented. The Monte Carlo ray-tracing method shows that the VPSS with a crater slope angle of about 50° has the highest LEE. To compare the optical characteristics, 380 nm ultraviolet LEDs were grown on an optimized VPSS, hemispherical PSS (HPSS), and planar sapphire substrate by metal-organic chemical vapor deposition (MOCVD). As a result, the extraction efficiency of the LED grown on the optimized VPSS was estimated to be almost 2.8 times larger than that of the planar sapphire substrate and was enhanced 1.6 times compared with that of the LED grown on the HPSS.
Ratio Effect of Codoped Spacer on Electroluminescent Characteristics of Hybrid White Organic Light-Emitting Diodes
Authors: Seo Ji Hoon , Park Jung Sun , Koo Ja Ryong , Lee Suk Jae , Seo Bo Min , Lee Kum Hee , Park Jung Keun , Yoon Seung Soo , Kim Young Kwan
Published: April 2010

The authors have demonstrated hybrid white organic light-emitting diodes (WOLEDs) using 1,4-bis[2-(7-N-diphenyamino-2-(9,9-diethyl-9H-fluoren-2-yl))vinyl] benzene as a fluorescent blue emitter and iridium(III) bis(2-phenylquinoline) acetylacetonate as a phosphorescent red emitter. As the spacer ratio of 4,4',4''-tris-(N-carbazolyl) triphenylamine to 4,7-diphenyl-1,10-phenanthroline changed from 1:1 to 1:3, WOLEDs showed changes from cold to warm electroluminescent characteristics. The optimized WOLEDs of 1:3 spacer ratio showed an external quantum efficiency of 7.40%, a luminous efficiency of 14.79 cd/A, and Commission Internationale de I'Eclairage coordinates of (0.43, 0.39) at 1000 cd/m2.
Data Transmission Scheme with Spectral Switches of a Tilting Circular Mirror in Far Field
Authors: Han Pin
Published: April 2010

An improved data transmission scheme that can be used for any chosen transmitting direction in free space is introduced. This scheme is obtained by analyzing the analytic form of the diffracted spectrum of a coherent broad band Gaussian spectrum incident on an adjustable tilting circular mirror. It is found that the transmitting angle and tilting angle are conjugate. The advantages of this method are that the transmission direction can be selected arbitrarily in advance and that it is easy to implement compared with other previous schemes which modulate some properties of the light source.
Study on the Valence State of Eu Ions in Sr3Al2O6:Eu Phosphor
Authors: Shin Hyun Ho , Kim Jin Hyung , Kim Kyung Pil , Han Bo Yong , Yoo Jae Soo
Published: April 2010

Europium-activated strontium aluminate phosphor, Sr3Al2O6:Eu2+, was prepared by solid-state reaction. The main concerns on the formation of a stable Sr3Al2O6 phase and the complete reduction of europium ions in this crystal phase, which is considered controversial in the literature and is available for white light-emitting-diode application, were addressed. It was found that the single phase of Sr3Al2O6 could be well formed and the valence state of europium ions depended on treatment temperature, flux, reduction gas, and the resultant stiffness of the host lattice. The redshift emission of Eu2+ in the Sr3Al2O6 host was not marked in our experimental regime. However, the green emission of Sr3Al2O6:Eu2+ increased gradually with the mole fraction of Al2O3 to SrCO3 in the starting materials owing to the complete formation of the Sr3Al2O6 phase.
Electro-Optic Characteristics of a Cooled Deuterated Potassium Dihydrogen Phosphate Crystal
Authors: Takeuchi Yasuki , Yoshida Akira , Tokita Shigeki , Fujita Masayuki , Kawanaka Junji
Published: April 2010

The half-wave voltage of a deuterated potassium dihydrogen phosphate (DKDP) crystal was measured between 231 K and room temperature. It was found to decrease linearly with crystal temperature at a rate of 55.1 V/K. The lowest voltage of 511 V was observed at 231 K, which is one eighth of that at room temperature. The cooled DKDP crystal was discussed for use as an electro-optic modulator as it provides various advantages such as the reduced voltage of the power supply needed and the lower B-integral.
Design of Element Configuration on Magnetic Rotation Angle Sensor with Spin-Valve Film
Authors: Okada Yasuyuki , Mitsumata Chiharu , Ishii Osamu
Published: April 2010

To reduce the error of a magnetic rotation angle sensor, we investigated the effect of sensor element configuration on the output signal of the sensor by using numerical calculations. The sensor elements were made of spin-valve films with a large shape-induced anisotropy. The magnetization of elements was calculated by minimizing the magnetic energy in a framework of the Stoner–Wohlfarth model. The sensor response was calculated as a function of the relative angle between the spin-valve elements. The error of signals was minimized when the relative angle was 99.5°. It is clear that this configuration is robust against the variation of shape-induced anisotropy.
Electrical Control of Magnetoresistance in Highly Insulating Co-Doped ZnO
Authors: Xu Qingyu , Zhou Shengqiang , Bürger Danilo , Hochmuth Holger , Lorenz Michael , Grundmann Marius , Schmidt Heidemarie
Published: April 2010

A Zn0.96Co0.04O film with low electron concentration (about 1.5 ×1017cm-3at 21 K) on a highly conducting Zn0.99Al0.01O layer has been deposited ona-plane sapphire substrate by pulsed laser deposition. To study the magnetoresistance (MR) of depleted, highly insulating Co-doped ZnO an Au ohmic contact and Pd Schottky contact were deposited on the Zn0.99Al0.01O and Zn0.96Co0.04O layer, respectively. Positive MR of 30% with a current of 10-6A was observed at 5 K. The positive MR decreases drastically at 5 K and changes to negative MR at 50 K with increasing current, which is considered to be due to the bias voltage control of the electron concentration in the Zn0.96Co0.04O layer. Our work demonstrates the electrically controllable magnetotransport behavior in insulating ZnO-based diluted magnetic semiconductors.
Local Oxidation Fin-Field-Effect-Transistor Structure for Nanodevice Applications
Authors: Tai Ya-Li , Lee Jam-Wem , Lien Chen-Hsin
Published: April 2010

Local oxidation (LOCOS) fin field-effect transistors (finFETs), a type of delta-FETs, are studied here for comparison with silicon-on-insulator (SOI) finFETs and bulk silicon finFETs. In our simulation, the LOCOS finFET shows a lower leakage current than the bulk finFET and a driving capability superior to that of the SOI finFET. The results can be attributed to the partial connection between the channel region and the substrate in LOCOS finFETs. The partially isolated oxide layer of LOCOS provides electrical isolation to suppress leakage, and the interspace between isolated oxide layers provides good thermal conduction to sustain a high driving current. For device fabrication, different parameters, fin height (H), gate length (L), and oxide interspace (S), are also investigated. The results show that the LOCOS finFET structure is an exceptional alternative for nanodevice applications.
Impact of Local High-k Insulator on Drivability and Standby Power of Gate-All-Around Silicon-on-Insulator Metal–Oxide–Semiconductor Field-Effect Transistor
Authors: Omura Yasuhisa , Hayashi Osanori , Nakano Shunsuke
Published: April 2010

In this paper, we study the impact of a local high-k gate insulator on the drivability and off-current of a gate-all-around (GAA) silicon-on-insulator (SOI) metal–oxide–semiconductor field-effect transistor (MOSFET). The replacement of part of the gate SiO2 film with a thick high-k insulator (for example, HfO2) results in the high drivability of the GAA MOSFET, which stems from the lateral extension of high gate-induced potential. A simulation was performed to determine the optimal width of the high-k insulator in order to realize the best performance. In addition, simulation results reveal that the parasitic resistance of the low-doped source and drain diffusion region is markedly reduced by the lateral extension of gate-induced potential because the crosssection of the silicon wire is very small.
Investigation of TiO2Thin Film Growth by Layer-by-Layer Self-Assembly for Application to Optical Devices
Authors: Kyung Kyu-Hong , Fujimoto Kouji , Shiratori Seimei , Kim Jin-Ho , Kim Sae-Hoon
Published: April 2010

Recently, optical thin films fabricated using a water-based process have been strongly demanded. We fabricated TiO2thin films consisting of poly(diallyl dimethyl ammonium chloride) (PDDA) and titanium(IV) bis(ammonium lactate) dihydroxide (TALH) for optical devices fabricated using layer-by-layer self-assembly. We report the effects of the pH and concentration of a solution, immersion time, and the amount of NaCl added to a solution on the thickness, morphology, surface roughness, and transmittance of fabricated thin films. The thickness, surface morphology, and transparency of (PDDA/TALH) thin films were determined by ellipsometry, field-emission scanning microscopy (FE-SEM), atomic force microscopy (AFM), and ultraviolet–visible (UV–vis) spectrometry. It was found that the thickness and surface morphology of (PDDA/TALH) multilayer films can be controlled by adjusting the TiO2particle size of TALH solution. TiO2particle size was controlled by adjusting the pH of TALH solution and the concentration of PDDA solution, and by adding NaCl to PDDA solution. It was found that we can increase deposition speed while maintaining optical quality by suppressing the surface roughness within 10 nm. These experimental results showed that the fabrication speed of thin films can be markedly increased, by approximately 6-fold.
Multi-Walled Carbon Nanotubes Growing Vertically from Root Particles
Authors: Chang Hui Lin , Kuo Cheng Tzu
Published: April 2010

The catalytic growth of multi-walled carbon nanotubes (MWCNTs) was performed on Si substrates with and without interfacial layers, by microwave plasma chemical vapor deposition (MPCVD). Many vertically grown, dense MWCNTs attached to a catalytic film penetrated the root particles. The diameter of root particles, in the order of 100 nm, is larger than the tube diameters of 10–15 nm. Base growth and tip growth are proposed as part of a new CNT growth model. The interaction between catalytic film and the supporting interfacial layer is suggested to determine whether the catalytic particles are driven up or pinned down on the substrate during the growth.
Ion Acceleration by the Coulomb Explosion of Graphene
Authors: Ming Chen , Lin Zheng-Zhe , Wang Yin , Zhang Wenxian , Zhuang Jun , Ning Xi-Jing
Published: April 2010

Coulomb explosion of graphene with different sizes and layers is investigated via molecular dynamics simulation. A group of collimated ions with average energy of keV can be obtained from the Coulomb explosion process of nanometer-scale multilayer graphene in a tube with nanometer-scale length, as the carbon ion taking on only 1+ charge. The average ion energy is found to be proportional to the square root of the number of atoms in a single layer while also proportional to layer numbers. According to this linear relationship, we estimate that collimated ions with average energy as high as MeV can be generated from graphene layers of several microns while the carbon ions taking on 3+ charge.
An X-ray Imaging System for Hard-to-Reach Facility Diagnosis Using Femtosecond Laser-Plasma
Authors: Oishi Yuji , Nayuki Takuya , Nakajima Chikahito , Fujii Takashi , Zhidkov Alexei , Nemoto Koshichi
Published: April 2010

For hard-to-reach facility diagnosis, a radiographic testing system that consists of a compact laser-plasma X-ray (LPX) generator and a compact X-ray imaging sensor is shown to be competitive to that based on the isotope imaging. A 1-mm-thick CsI charge-coupled device (CCD) sensor supplied with a cooling system was developed to tolerate a long X-ray exposition. Even without optimization of X-ray yield from a Ta thin film irradiated by 230 mJ, 70 fs laser pulses, clear X-ray images of a SUS304 pipe (outer diameter 34 mm with 4.5 mm thickness) with an elbow were produced.
Study of Dual-Laser-Generated Surface Acoustic Waves Interacting with Multiangled Surface Breaking Cracks by Finite Element Method
Authors: Ni Chenyin , Shi Yifei , Shen Zhonghua , Lu Jian
Published: April 2010

In this paper we study the situation of a laser line source directly irradiating a crack modeled by a slot, which is an essential process in the scanning laser line source (SLLS) technique. The finite element method (FEM) was used to calculate the scattering of an ultrasonic wave. The propagation paths of ultrasonic waves were analyzed and corresponding waves were identified accordingly. The displacements for various slot orientations were then calculated and analyzed, and it was shown that the arrival times of some ultrasonic wave modes can be used for detecting the slot orientation. As a result, the relationship between the slot orientation and the ultrasound diffraction pattern was clarified.
Unique Reflection Property Due to Bumpy Multilayer Structure in Elytra of Rhomborrhina unicolor
Authors: Edo Susumu , Okoshi Kento , Kang Sungmin , Tokita Masatoshi , Watanabe Junji
Published: April 2010

Various species of animals use microstructures in their bodies to produce brilliant colors called structural colors. In this study, we analyzed the glossy green structural color ofRhomborrhina unicolor(a coleoptera) using scanning transmission electron microscopy (STEM) and reflection spectroscopy. The reflector in the elytra ofR. unicoloris composed of a bumpy multilayer whose tilting angle to the elytron surface is approximately 20°, as revealed by STEM and reflection spectroscopy. This bumpiness broadens the reflection band. In other words, the green light is reflected over a broad range of angles to the elytron surface, which may be helpful in camouflage, conspecific recognition, and so forth.
Influence of Carbon in In-situ Carbon-Doped SiGe Films on Si(001) Substrates on Epitaxial Growth Characteristics
Authors: Oomae Hiroto , Itokawa Hiroshi , Mizushima Ichiro , Nakamura Shinichi , Uchitomi Naotaka
Published: April 2010

Carbon doped SiGe (SiGe:C)/Si(001) heterostructure were grown by reduced pressure chemical vapor deposition using silane, germane and methylsilane as a source of Si, Ge, and C, respectively. We performed a systematic experiment of growth of SiGe:C and carried out measurements to determine the surface roughness and occupation sites of carbon atoms as functions of C source flow, Ge concentration, growth temperature and growth rate. Ge concentration range was from 0 to 23.0%. Growth temperature was 575 to 625 °C. The range of Growth rate was between 1.5 and 4.3 Å/s. These SiGe:C analyzed by atomic force microscopy (AFM), secondary ion mass spectrometry (SIMS), high-resolution X-ray diffraction (HR-XRD) and cross-sectional transmission electron microscopy (TEM). Total C compositions did not depend on growth temperature with the constant Ge concentration and with SiH3CH3 flow ratio. Surface roughness of SiGe:C with high Ge concentration increased with the increase of C source gas flow. Interstitial C concentration in SiGe:C films with rough surface increased with the increase of C source gas flow. The roughness of SiGe:C layer grown constant C gas source flow ratio decreased for low growth temperature and/or faster growth rate. From these results, we revealed that the mechanism of defect formation with localized C as the cause of rough. The excess migration can suppress surface roughness.