bluuebunny/crossref_metadata_2025 huggingface dataset:
The Influence of Higher-Order Mode Shapes for Reduced-Order Models of Electrostatically Actuated Microbeams
Authors: Gutschmidt Stefanie
Published: April 2010

Reduced-order models for micro-electromechanical structures possess several attractive features when compared with computational approaches using, e.g., finite-element packages. However, also within the business of reduced-order modeling, there are different approaches that yield different results. The efficiency of such approaches has to be judged according to, first, the purposes and aims of the model and, second, according to computational expenses and modeling efforts. This paper deals specifically with the frequently asked question of how many modes have to be considered in the discretization procedure to ensure an efficient reduced-order model. A consistent nonlinear continuum model is employed to describe a doubly clamped microbeam subject to two cases of electromechanical actuation. The analysis, confined to the static behavior, concentrates on two discretization techniques and addresses the differences between the final reduced-order models, accordingly. The results show significant differences with respect to the number of implemented linear-undamped mode shape functions, which are used as basis functions in the approximation procedure. This is demonstrated for the two mentioned distinct excitation schemes of the doubly clamped microbeam. The purposes of this paper are twofold. First, it draws attention to the differences between reduced-order models, which have been discretized one way or the other according to investigation goals and purposes. Second, it serves as a guideline for future micro- and nano-electromechanical system modeling by elaborating the advantages and disadvantages of both techniques.
Viscoplastic Effects Occurring in Impacts of Aluminum and Steel Bodies and Their Influence on the Coefficient of Restitution
Authors: Seifried Robert , Minamoto Hirofumi , Eberhard Peter
Published: April 2010

Generally speaking, impacts are events of very short duration and a common problem in machine dynamics. During impact, kinetic energy is lost due to plastic deformation near the contact area and excitation of waves. Macromechanically, these kinetic energy losses are often summarized and expressed by a coefficient of restitution, which is then used for impact treatment in the analysis of the overall motion of machines. Traditionally, the coefficient of restitution has to be roughly estimated or measured by experiments. However, more recently finite element (FE) simulations have been used for its evaluation. Thereby, the micromechanical plastic effects and wave propagation effects must be understood in detail and included in the simulations. The plastic flow, and thus the yield stress of a material, might be independent or dependent of the strain-rate. The first material type is called elastic-plastic and the second type is called elastic-viscoplastic. In this paper, the influence of viscoplasticity of aluminum and steel on the impact process and the consequences for the coefficient of restitution is analyzed. Therefore, longitudinal impacts of an elastic, hardened steel sphere on aluminum AL6060 rods and steel S235 rods are investigated numerically and experimentally. The dynamic material behavior of the specimens is evaluated by split Hopkinson pressure bar tests and a Perzyna-like material model is identified. Then, FE impact simulations and impact experiments with laser-doppler-vibrometers are performed. From these investigations it is shown that strain-rate effects of the yield stress are extremely small for impacts on aluminum but are significant in impacts on steel. In addition, it is demonstrated that it is possible to evaluate for both impact systems the coefficient of restitution numerically, whereas for the aluminum body a simple elastic-plastic material model is sufficient. However, for the steel body an elastic-viscoplastic material model must be included.
Shock Waves in Dynamic Cavity Expansion
Authors: Cohen Tal , Masri Rami , Durban David
Published: April 2010

High velocity cavitation fields are investigated in the context of large strain J2 plasticity with strain hardening and elastic compressibility. The problem setting is that of an internally pressurized spherical cavity, embedded in an unbounded medium, which grows spontaneously with constant velocity and pressure. Expansion velocity is expected to be sufficiently high to induce a plastic shock wave, hardly considered in earlier dynamic cavitation studies. Jump conditions across singular spherical surfaces (shock waves) are fully accounted for and numerical illustrations are provided over a wide range of power hardening materials. Simple formulae are derived for shock wave characteristics and for the asymptotic behavior within near cavity wall boundary layer.
Errors Caused by Non-Work-Conjugate Stress and Strain Measures and Necessary Corrections in Finite Element Programs
Authors: Ji Wooseok , Waas Anthony M. , Bažant Zdeněk P.
Published: April 2010

Many finite element programs including standard commercial software such as ABAQUS use an incremental finite strain formulation that is not fully work-conjugate, i.e., the work of stress increments on the strain increments does not give a second-order accurate expression for work. In particular, the stress increments based on the Jaumann rate of Kirchhoff stress are work-conjugate with the increments of the Hencky (logarithmic) strain tensor but are paired in many finite element programs with the increments of Green’s Lagrangian strain tensor. Although this problem was pointed out as early 1971, a demonstration of its significance in realistic situations has been lacking. Here it is shown that, in buckling of compressed highly orthotropic columns or sandwich columns that are very “soft” in shear, the use of such nonconjugate stress and strain increments can cause large errors, as high as 100% of the critical load, even if the strains are small. A similar situation may arise when severe damage such as distributed cracking leads to a highly anisotropic tangential stiffness matrix, or when axial cracks between fibers severely weaken a uniaxial fiber composite or wood. A revision of these finite element programs is advisable, and will in fact be easy—it will suffice to replace the Jaumann rate with the Truesdell rate. Alternatively, the Green’s Lagrangian strain could be replaced with the Hencky strain.
Magnetorheological Fluid Flow in Microchannels
Authors: Whiteley Joseph , Gordaninejad Faramarz , Wang Xiaojie
Published: April 2010

This study presents experimental results on the flow of magnetorheological grease (MRG) through microchannels. MR materials flowing through microchannels create microvalves. The flow is controlled by injecting the MRG through microchannels with controlled adjustable rates. To study the effect of different channel diameters and surface roughnesses, microchannels made of stainless steel, PEEK, and fused silica materials with nominal internal diameters ranging from 1 mm to 0.075 mm (75 μm) are tested. A magnetic field is applied perpendicular to the microchannel flow and is controlled by an input electric current. The pressure drop of the flow is measured across the length of the microchannels. The dynamic pressure drop range and surface roughness effects are also discussed. The Herschel–Bulkley model for non-Newtonian fluid flow is employed to the experimental results with good agreement. The results show a significant pressure drop for different magnetic field strengths.
Adhesion Between Thin Cylindrical Shells With Parallel Axes
Authors: Majidi Carmel , Wan Kai-tak
Published: April 2010

Energy principles are used to investigate the adhesion of two parallel thin cylindrical shells under external compressive and tensile loads. The total energy of the system is found by adding the strain energy of the deformed cylinder, the potential energy of the external load, and the surface energy of the adhesion interface. The elastic solution is obtained by linear elastic plate theory and a thermodynamic energy balance, and is capable of portraying the measurable quantities of external load, stack height, contact arc length, and deformed profile in the reversible process of loading-adhesion and unloading-delamination. Several worked examples are given as illustrations. A limiting case of adhering identical cylinders is shown to be consistent with recent model constructed by Tang et al. Such results are of particular importance in modeling the aggregation of heterogeneous carbon nanotubes or cylindrical cells, where the contacting microstructures have a different radius and/or bending stiffness.
Time-Decaying Uniform Stresses Inside an Anisotropic Elliptical Inhomogeneity With Nonuniform Interfacial Slip
Authors: Wang Xu
Published: April 2010

This study addresses the problem of an elastically anisotropic elliptical inhomogeneity bonded to an infinite elastically anisotropic matrix through a linear viscous interface. Our results show that uniform, as well as time-decaying stresses, still exist inside the elliptical inhomogeneity when the interface drag parameter, which is varied along the interface, is properly designed, and when the matrix is subjected to remote uniform antiplane shearing. Interestingly, the internal stresses decay with not one but two relaxation times. Some special cases are discussed in detail to demonstrate the obtained solutions.
Effects of the size of silicon grain on the gate-leakage current in nanocrystalline silicon thin-film transistors
Authors: Mao Ling-Feng
Published: April 2010

The size of silicon grain in silicon thin-film transistors (TFTs) and the dependence of the gate-leakage current have been theoretically investigated after the effect of the silicon-grain size on the surface potential is considered. After the crystal-size effect has been included, the gate-leakage current of nanocrystalline silicon TFTs strongly depends on the silicon-grain size when the silicon-grain size is in the regime of nanoscale. Such a strong dependent relation results from the large changes in the band gap and dielectric constant due to size effects. The numerical calculations also demonstrate that the effect of the silicon-grain size on the gate-leakage current is independent (or weakly dependent) on the device temperature, the gate voltage, and the active-dopant density.
n
-type InP Schottky diodes with organic thin layer: Electrical and interfacial properties
Authors: Güllü Ö. , Türüt A.
Published: April 2010

The rectifying junction characteristics of methyl red (MR) organic film on n-type InP substrate have been studied. It has been observed that MR-based structure shows an excellent rectifying behavior and that the MR film increases the effective barrier height by influencing the space charge region of the n-type InP. The barrier height and ideality factor values for this structure have been obtained as 0.75 eV and 1.93 from the forward bias current-voltage characteristics, respectively. By using capacitance-voltage characteristics at 1 MHz, the barrier height and the carrier concentration values have been calculated as 0.93 eV and 5.13×1015 cm−3, respectively. The energy distributions of the interface states and their relaxation times have been determined from the forward bias capacitance-frequency and conductance-frequency characteristics. Moreover, it was seen that both the interface-state density and the relaxation time of the interface states decreased with bias voltage from experimental results.
Mn-induced growth of InAs nanowires
Authors: Jabeen F. , Piccin M. , Felisari L. , Grillo V. , Bais G. , Rubini S. , Martelli F. , d’Acapito F. , Rovezzi M. , Boscherini F.
Published: April 2010

InAs nanowires have been grown by molecular beam epitaxy using Mn as growth catalyst. Nanowires (NWs) have been obtained on SiO2 and oxidized GaAs for growth temperatures in the range of 370–410 °C. The growth temperature is found to be the same as that of the growth of Au-catalyzed InAs wires. These results suggest that the InAs NWs grow with the Mn nanoparticle in the solid phase and allow some comparison with the existing models for Au-catalyzed nanowires. The morphology and the lattice structure were investigated by electron microscopy techniques. The lattice of the wire body is found to be mainly wurtzite InAs. Mn K-edge x-ray absorption fine structure was used to determine the local environment of the Mn atoms: The authors found that most of the Mn atoms are found in a hexagonal MnAs phase.
Effect of the Preparation Procedure on the Surface Properties of Nanosized Ceria Powders
Authors: Natile Marta Maria , Galenda Alessandro , Glisenti Antonella
Published: April 2010

Nanosized cerium (IV) oxide powders were synthesized using three different preparation procedures: (1) precipitation from a basic solution of cerium nitrate containing H2O2 at 273 K; (2) Marcilly method, and (3) microemulsion method. In this work the influence of the preparation procedure on the surface properties is studied by means of XPS. Besides the wide scan spectrum, detailed spectra for the Ce 3d, Ce 4d, O and 1s and regions and relative data are presented and discussed.
ZnxNi1-xO Mixed-Metal Oxides by AES
Authors: Gaskell Karen J. , Starace Anne , Langell Marjorie A.
Published: April 2010

ZnxNi1-xO samples with a compositional range 0 < × ≤ 0.3 were synthesized via thermal dissolution in air and their surface characterized with Auger electron spectroscopy (AES). AES analysis shows the surface composition to be comparable to the bulk composition. These systems are interesting as they place zinc in an octahedral environment which is unusual for zinc normally preferring a tetrahedral environment. This submission contains survey spectra for the homogeneous solid solutions, Zn0.05Ni0.95O, Zn0.1Ni0.9O, Zn0.2Ni0.8O, Zn0.3Ni0.7O and for pure NiO and ZnO. All samples have the rocksalt crystal structure except ZnO which has the Wurtzite crystal structure.
CVD Cu2O and CuO Nanosystems Characterized by XPS
Authors: Barreca Davide , Gasparotto Alberto , Tondello Eugenio
Published: April 2010

In the present investigation, X-ray photoelectron and X-ray excited Auger electron spectroscopy analyses of the principal core levels (O 1s, Cu 2p, and Cu LMM) of Cu2O and CuO nanosystems are proposed. The samples were obtained by chemical vapor deposition starting from a novel second-generation copper(II) precursor, Cu(hfa)2·TMEDA (hfa=1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; TMEDA=N,N,N′,N′-tetramethylethylenediamine), under a dry O2 atmosphere. The obtained route led to pure, homogeneous and single-phase Cu(I) and Cu(II) oxide nanosystems at temperatures of 300 and 500 °C, respectively, whose chemical nature could be conveniently distinguished by analyzing the Cu 2p band shape and position, as well as by evaluating the Auger parameters. The samples were characterized by O/Cu atomic ratios greater than the expected stoichiometric values, due to marked interactions with the outer atmosphere attributed to their high surface-to-volume ratio.
Nanostructured Dy2O3 films: An XPS Investigation
Authors: Barreca Davide , Gasparotto Alberto , Milanov Andrian , Tondello Eugenio , Devi Anjana , Fischer Roland A.
Published: April 2010

The present investigation is devoted to the X-ray photoelectron spectroscopy (XPS) analysis of the main core levels (C 1s, O 1s, Dy 4d, Dy 3d) of a representative dysprosium(III) oxide thin film. The specimen was grown on Si(100) at 500 °C by metal organic chemical vapor deposition (MOCVD) starting from Dy((iPrN)2CNMe2)3 in an N2/O2 atmosphere. The above route yielded uniform and homogeneous nanostructured Dy2O3 films characterized by a remarkable reactivity towards atmospheric CO2 and H2O, resulting in the surface co-presence of dysprosium carbonates/bicarbonates and hydroxides. The most relevant spectral features are presented and discussed.
Sm–Nd geochemistry and U–Pb geochronology of the Preissac and Lamotte leucogranites, Abitibi Subprovince
Authors: Ducharme Yan , Stevenson Ross K. , Machado Nuno
Published: April 2010

The Lacorne Block in the Southern Volcanic Zone of the Abitibi Subprovince is composed of interleaved metavolcanic and metasedimentary rocks that are intruded by syn- to posttectonic diorites, granodiorites, and granites. These rocks form the Lacorne, Lamotte, and Preissac plutons, which can be divided into an early suite of dioritic–granodioritic rocks and a later suite of S-type, leucocratic granites with an estimated age of 2640 Ma. This study presents Sm–Nd data and U–Pb monazite and titanite ages for the late leucocratic granites of the Preissac and Lamotte plutons. A biotite–muscovite monzogranitic phase of the Lamotte pluton is dated at 2647 ± 2 Ma, but similar phases of the Preissac pluton are dated at 2681–2660 Ma. These ages extend the period of leucogranitic plutonism for this area to 40 Ma and suggest that the age of collision of the Abitibi and the Pontiac subprovinces occurred before 2685 Ma. The εNd values for the leucogranites range from −1 to +3 and suggest an origin largely through melting of sediments having a juvenile isotopic signature (i.e., a short crustal residence time). Possible sources of the leucogranites include metasedimentary rocks of the Pontiac Subprovince, the Lacorne Block, and the Southern Abitibi Volcanic Zone, but the εNd values of the granites are most consistent with melting of metasediments of the Southern Volcanic Zone. We suggest that sediments of the Southern Volcanic Zone formed an accretionary prism along the southern continental margin of the Abitibi before collision with the Pontiac Subprovince. This prism was subsequently trapped between the two colliding margins, subducted, and partially melted to produce the Lamotte, Preissac, and Lacorne leucogranites.
COVERS OF SURFACES WITH FIXED BRANCH LOCUS
Authors: EDIXHOVEN BAS , DE JONG ROBIN , SCHEPERS JAN
Published: April 2010

Given a connected smooth projective surface X over ℂ, together with a simple normal crossings divisor D on it, we study finite normal covers Y → X that are unramified outside D. Given further a fibration of X onto a curve C, we prove that the "height" of Y over C is bounded linearly in terms of the degree of Y → X. We indicate how an arithmetic analog of this result, if true, can be auxiliary in proving the existence of a polynomial time algorithm that computes the mod-ℓ Galois representations associated to a given smooth projective geometrically connected surface over ℚ. A precise conjecture is formulated.
GEOMETRY OF QUASI-FREE STATES OF CCR ALGEBRAS
Authors: YAMAGAMI SHIGERU
Published: April 2010

Geometric positions of square roots of quasi-free states of CCR algebras are investigated together with an explicit formula for transition amplitudes among them.
ARITHMETIC-GEOMETRIC MEANS FOR HYPERELLIPTIC CURVES AND CALABI–YAU VARIETIES
Authors: MATSUMOTO KEIJI , TERASOMA TOMOHIDE
Published: April 2010

In this paper, we define a generalized arithmetic-geometric mean μg among 2g terms motivated by 2τ-formulas of theta constants. By using Thomae's formula, we give two expressions of μg when initial terms satisfy some conditions. One is given in terms of period integrals of a hyperelliptic curve C of genus g. The other is by a period integral of a certain Calabi–Yau g-fold given as a double cover of the g-dimensional projective space Pg.
THE SASAKI–RICCI FLOW
Authors: SMOCZYK KNUT , WANG GUOFANG , ZHANG YONGBING
Published: April 2010

In this paper, we introduce the Sasaki–Ricci flow to study the existence of η-Einstein metrics. In the positive case any η-Einstein metric can be homothetically transformed to a Sasaki–Einstein metric. Hence it is an odd-dimensional counterpart of the Kähler–Ricci flow. We prove its well-posedness and long-time existence. In the negative or null case the flow converges to the unique η-Einstein metric. In the positive case the convergence remains in general open. The paper can be viewed as an odd-dimensional counterpart of Cao's results on the Kähler–Ricci flow.
HYBRID TECHNOLOGY FOR SELF-ORGANIZATION OF RESOURCES OF PERVASIVE ENVIRONMENT FOR OPERATIONAL DECISION SUPPORT
Authors: SMIRNOV ALEXANDER , LEVASHOVA TATIANA , SHILOV NIKOLAY , KASHEVNIK ALEXEY
Published: April 2010

The paper addresses the development of a hybrid technology for operational decision support in a pervasive environment. The technology encompasses the idea of implementing a decision support system as a set of Web-services. The Web-services are intended to form an ad-hoc collaborative environment, whose members cooperate with an objective of serving the current needs according to the decision situation. The collaborative environment is made up of resources of a pervasive environment. The technology is focused on three types of resources to be organized: information, problem-solving, and acting, and is supported by a service-based architecture of the decision support system providing types of Web-services needed for this technology implementation. The hybrid technology integrates technologies of ontology management, context management, constraint satisfaction, Web-services, profiling, and intelligent agents. The technology application is illustrated by the decision support for dynamic logistics.
ACCRETION AND PLASMA OUTFLOW FROM DISSIPATIONLESS DISCS
Authors: BOGOVALOV S. V. , KELNER S. R.
Published: April 2010

We consider the specific case of disc accretion for negligibly low viscosity and infinitely high electric conductivity. The key component in this model is the outflowing magnetized wind from the accretion disc, since this wind effectively carries away angular momentum of the accreting matter. Assuming magnetic field has variable polarity in the disc (to avoid magnetic flux and energy accumulation at the gravitational center), this leads to radiatively inefficient accretion of the disc matter onto the gravitational center. In such a case, the wind forms an outflow, which carries away all the energy and angular momentum of the accreted matter. Interestingly, in this framework, the basic properties of the outflow (as well as angular momentum and energy flux per particle in the outflow) do not depend on the structure of accretion disc. The self-similar solutions obtained prove the existence of such an accreting regime. In the self-similar case, the disc accretion rate (Ṁ) depends on the distance to the gravitational center, r, as [Formula: see text], where λ is the dimensionless Alfvenic radius. Thus, the outflow predominantly occurs from the very central part of the disc provided that λ ≫ 1 (it follows from the conservation of matter). The accretion/outflow mechanism provides transformation of the gravitational energy from the accreted matter into the energy of the outflowing wind with efficiency close to 100%. The flow velocity can essentially exceed the Kepler velocity at the site of the wind launch.
ANGULAR SIZE TEST ON THE EXPANSION OF THE UNIVERSE
Authors: LÓPEZ-CORREDOIRA MARTÍN
Published: April 2010

Assuming the standard cosmological model to be correct, the average linear size of the galaxies with the same luminosity is six times smaller at z = 3.2 than at z = 0; and their average angular size for a given luminosity is approximately proportional to z-1. Neither the hypothesis that galaxies which formed earlier have much higher densities nor their luminosity evolution, merger ratio, and massive outflows due to a quasar feedback mechanism are enough to justify such a strong size evolution. Also, at high redshift, the intrinsic ultraviolet surface brightness would be prohibitively high with this evolution, and the velocity dispersion much higher than observed. We explore here another possibility of overcoming this problem: considering different cosmological scenarios, which might make the observed angular sizes compatible with a weaker evolution.

One of the explored models, a very simple phenomenological extrapolation of the linear Hubble law in a Euclidean static universe, fits quite well the angular size versus redshift dependence, also approximately proportional to z-1 with this cosmological model. There are no free parameters derived ad hoc, although the error bars allow a slight size/luminosity evolution. The supernova Ia Hubble diagram can also be explained in terms of this model without any ad-hoc-fitted parameter.

NB: I do not argue here that the true universe is static. My intention is just to discuss which intellectual theoretical models fit better some data of the observational cosmology.
DRESSING A NAKED SINGULARITY: AN EXAMPLE
Authors: BRANDT C. F. C. , CHAN R. , DA SILVA M. F. A. , VILLAS DA ROCHA JAIME F.
Published: April 2010

Considering the evolution of a perfect fluid with self-similarity of the second kind, we find that an initial naked singularity can be trapped by an event horizon due to collapsing matter. The fluid moves along timelike geodesics with a self-similar parameter α = -3. Since the metric obtained is not asymptotically flat, we match the space–time of the fluid with a Schwarzschild space–time. All the energy conditions are fulfilled until the naked singularity.
COSMOLOGICAL ROLLING SOLUTIONS OF NONLOCAL THEORIES
Authors: CALCAGNI GIANLUCA , NARDELLI GIUSEPPE
Published: April 2010

We find nonperturbative solutions of a nonlocal scalar field equation, with cubic or exponential potential on a cosmological background. The former case corresponds to the lowest level effective tachyon action of cubic string field theory. While the well known Minkowski solution is wildly oscillating, due to Hubble friction its cosmological counterpart describes smooth rolling toward the local minimum of the potential.
INVARIANCE OF SUBSPACES UNDER THE SOLUTION FLOW OF SPDE
Authors: LIU WEI
Published: April 2010

In this paper we investigate some regularity property for the solution to SPDE. Under certain assumptions we prove that the solution of an SPDE takes values in some subspace of the original state space if the initial condition does so. As examples, the main result is applied to different types of SPDE such as stochastic reaction-diffusion equations, the stochastic p-Laplace equation, stochastic porous media and fast diffusion equations in Hilbert space.
MULTIPLE MARKOV GENERALIZED GAUSSIAN PROCESSES AND THEIR DUALITIES
Authors: SI SI
Published: April 2010

A stochastic process describes evolutional random phenomena towards future. Corresponding with this direction, there will be a process describing, as it were, backward evolution from future to present. The dual process is a realization of this fact.

We restrict our attention to Gaussian processes for which multiple Markov property is well investigated. This property expresses way of dependence of involved randomness as time goes by. We can therefore expect that such a process with multiple Markov property would present an exact form of the dual process.

We shall show that having defined generalized Gaussian process with multiple Markov property, we can construct the dual process satisfying the properties that we claim. The analysis for this can be done in the space of Hida distributions.
EXISTENCE, UNIQUENESS AND REGULARITY w.r.t. THE INITIAL CONDITION OF MILD SOLUTIONS OF SPDEs DRIVEN BY POISSON NOISE
Authors: PRÉVÔT CLAUDIA INGRID
Published: April 2010

In this paper we investigate stochastic partial differential equations in a separable Hilbert space driven by a compensated Poisson random measure. Our interest is directed towards the existence and uniqueness of mild solutions and their regularity w.r.t. the inital condition. We show the existence of a unique mild solution and prove the Gâteaux differentiability of the mild solution w.r.t. the initial condition. As a consequence, we obtain a gradient estimate for the Gâteaux derivative of the mild solution and for the resolvent associated to the mild solution.
Heteronuclear lanthanide-containing complexes on the base of modified porphyrins and their luminescent properties
Authors: Rusakova Natalya , Semenishyn Nikolay , Korovin Yuriy
Published: April 2010

The mono- and heteronuclear complexes of the general formula M-ATPP-Ln-L ( Ln = Yb , Lu; M = Zn , Cu , 2H ; ATPP - mono-p-aminotetraphenylporphyrin; L = EDTA - ethylenediaminetetraacetic acid or DTPA - diethylenetriaminepentaacetic acid) were prepared and characterized by elemental analysis, MS, 1H NMR, UV-vis and luminescent spectra. In all compounds the lanthanide ion is coordinated by aminopolycarboxylic fragment only. The spectra of metal complexes were compared with those of free-base porphyrins. Luminescence studies showed that porphyrin fragment of ligands absorbed the visible light and transferred the energy to lanthanide (ytterbium) ion emitting in the near IR-region. Efficiency of the 4f-luminescence has been determined for d-f-metal containing porphyrin complexes in comparison with the mononuclear Yb-containing complexes in DMF solutions.
A manganese porphyrin-based sensor for flow-injection potentiometric determination of thiocyanate
Authors: Beheshti Saeed S. , Sohbat Fatemeh , Amini Mohammad K.
Published: April 2010

Metalloporphyrin-based ion-selective electrodes for flow-injection potentiometric determination of thiocyanate are described. The detection system is based on a coated glassy carbon electrode membrane sensor incorporating 5,10,15,20-tetraphenyl-21H,23H-porphine manganese(III) chloride as the active ingredient. The influences of the membrane composition, pH, and the effects of flow-injection parameters on the response of the system were investigated. At the optimized flow-injection potentiometric conditions, the sensor exhibited a Nernstian slope of -58.0 mV per decade of thiocyanate activity over the range 4.2 × 10-7–7.6 × 10-2M , where 50 μL of each sample solution was injected into the carrier solution. The detection limit of thiocyanate in the FIP mode was 4.2 × 10-7M . The selectivity of the flow-injection potentiometric system with respect to several common inorganic and organic anions was superior to that of the batch mode using the same sensor and similar operating conditions. The sensor was applied to the determination of thiocyanate in urine samples.
DDT-reductive dechlorination catalyzed by cobalt phthalocyanine, 2,3- and 3,4-tetrapyridoporphyrazine complexes in non-aqueous media
Authors: Shao Jianguo , Thomas Abegayl , Han Baocheng , Hansen Christopher A.
Published: April 2010

Neutral cobalt(II) phthalocyanine and 2,3- and 3,4-tetrapyridoporphyrazine complexes were examined in pyridine, dimethyl sulfoxide and N,N-dimethylformamide to evaluate their catalytic properties in the reductive dechlorination of 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane (p,p'-DDT). Cyclic voltammetry, controlled potential bulk electrolysis and thin-layer UV-visible spectroelectrochemistry of each compound in the presence of DDT indicated that both the singly and doubly reduced species, [Co(I)]- and [Co(I)]2- , can catalyze the dechlorination of DDT through the formation of, and a photoinduced or electrochemically induced cleavage of, the Co-C bond in the organometallic intermediates. GC-MS analysis revealed that DDT was converted to 1,1-bis(4-chlorophenyl)-2, 2-dichloroethane (p,p'-DDD), 1,1-bis(4-chlorophenyl)-2,2-dichloroethylene (p,p'-DDE) and 1,1-bis(4-chlorophenyl)-2-chloroethylene (p,p'-DDMU), upon dechlorination. The catalytic performance of the three cobalt complexes depends upon the reactive nature of each compound, the solvent, the reaction time and the equivalence of DDT. In addition, either DDD or DDE can be catalytically dechlorinated to generate DDMU, possibly through a similar mechanism.
Light-induced hole transfer in a hypervalent phosphorus(V) octaethylporphyrin bearing an axially linked bis(ethylenedithio)tetrathiafulvalene
Authors: Poddutoori Prashanth K. , Dion Ann , Yang Songjie , Pilkington Melanie , Wallis John D. , van der Est Art
Published: April 2010

A phosphorus(V) porphyrin bearing an axially linked bis(ethylenedithio)tetrathiafulvalene, dyad 1, and its radical cation phosphorus(V) porphyrin- O-CH2 -(bis(ethylenedithio)tetrathiafulvalene)+•, dyad 2, have been synthesized and studied as an electron hole donor-acceptor system. The absorption spectrum of dyad 1 does not show evidence for electronic coupling between the porphyrin and the bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) moieties. However, the steady-state fluorescence of the porphyrin chromophore is quantitatively quenched and its transient fluorescence lifetime is shortened compared to a reference compound in which the BEDT-TTF moiety is replaced by a methoxy group. Chemical oxidation of the BEDT-TTF moiety in dyad 1 to give dyad 2 results in recovery of the fluorescence intensity. This behavior suggests that the fluorescence quenching in dyad 1 is the result of intramolecular hole transfer from the the excited porphyrin to the BEDT-TTF moiety. The occurence of hole transfer in dyad 1 is confirmed by freeze-trapping and time-resolved electron paramagnetic resonance (EPR) measurements. The freeze-trapping EPR experiments show that steady-state irradiation of the complex leads to accumulation of its radical cation (dyad 2) while the transient EPR measurements at 5 °C show that flash irradiation of dyad 1 results in formation of a radical-ion pair with a lifetime of at least 300 ns. The triplet state of the porphyrin, which is formed by intersystem crossing and gives a strong transient EPR spectrum in the reference compound, is not observed for dyad 1. Together, the fluorescence quenching and the polarization pattern of the radical pair suggest that the hole transfer occurs from the excited singlet state of the porphyrin with high efficiency.
3D seismic evidence of internal structure within Tampen Slide deposits on the North Sea Fan: are chaotic deposits that chaotic?
Authors: Gafeira J. , Long D. , Scrutton R. , Evans D.
Published: April 2010

The seismic character of slide deposits is typically described as structureless or chaotic. However, 3D seismic data from the northern flank of the North Sea Fan reveal recognizable internal, penetrative structures within the Tampen Slide deposits. The study of its seismic attributes allowed an integrated characterization of the slide deposits and has shown distinctive acoustic fabrics, both at the top and base of the slide deposit, which are interpreted to be the expression of internal deformation structures. Based on their geometry, four main seismic fabric types have been defined: anastomosing, curvilinear, rectilinear and wispy. The spatial distribution of the fabric was mainly controlled by a topographic high present on the sea-bed at the time of the gravitational collapse, which influenced the transport of material. Areas of distinct fabrics are thought to reflect different flow behaviour during the latest stages of the mass movement and could be considered kinematic indicators. The results give new insights into the transport and deformation processes of submarine mass movements and highlight the potential of detailed analysis of 3D seismic data.
Zircon dating ties NE Atlantic sill emplacement to initial Eocene global warming
Authors: Svensen Henrik , Planke Sverre , Corfu Fernando
Published: April 2010

The Earth experienced rapid greenhouse gas induced global warming during the Palaeocene–Eocene thermal maximum (PETM). The source of the gas is, however, debated. We have, for the first time, determined the ages of magmatic sills in the Vøring Basin offshore Norway. Zircon U–Pb ages of 55.6 ± 0.3 and 56.3 ± 0.4 Ma demonstrate that sill emplacement was synchronous with the PETM within small errors. This discovery strengthens the hypothesis that global warming was triggered by rapid release of greenhouse gases generated by heating of organic-rich sediments around intrusions in the NE Atlantic rather than from dissociation of gas hydrates.

Supplementary material:

U–Pb data are available at
http://www.geolsoc.org.uk/SUP18392
.
Geodynamic evolution of the Aegean: constraints from the Plio-Pleistocene volcanism of the Volos–Evia area
Authors: Innocenti F. , Agostini S. , Doglioni C. , Manetti P. , Tonarini S.
Published: April 2010

The Plio-Pleistocene lava flows and domes of the Volos–Evia area were erupted between 3.4 and 0.5 Ma ago on the western continuation of the North Anatolian Fault, in a back-arc position with respect to the active arc. They are mainly high-K calc-alkaline trachyandesites. Based on their Sr–Nd–Pb isotopic compositions, the mantle source of the Volos–Evia area lavas is similar to that of a large volcanic belt that developed north of the Pelagonian–Attic–Cycladic–Menderes massifs, encompassing a 35 Ma timespan and widespread over a large area from NW Greece–Macedonia to the Aegean–western Anatolia. In contrast, southern Aegean arc rocks have a similar subduction fingerprint but distinctly lower Sr and higher Nd isotopic compositions. The geochemical and isotopic differences between southern and northern Aegean rocks may be ascribed to the different nature of the mantle wedge: depleted asthenosphere under the the southern Aegean, and lithosphere northward. The lack of an asthenospheric mantle wedge below the northern Aegean fits with the hypothesis of an almost horizontal subduction of the African slab. In the mantle reference frame the African slab is moving out of the mantle, and a slab-driven suction flow of the underlying mantle may be responsible for the recent development of a thin asthenospheric layer in the southern Aegean mantle wedge.
(Invited) A Brain-Inspired VLSI Architecture for Nano Devices and Circuits
Authors: Shibata Tadashi
Published: April 2010

What kind of system is most suited to implementation in nanoelectronics? A human-like intelligent system is proposed as one of the most promising candidates. In order to achieve human-like recognition performance, various types of sensing devices are required to gather information from environment, a large capacity of memories for learning from experience, and huge computational powers for recognition and understanding. Multifunctional device integration would certainly provide a platform for such system implementation. However, regarding the computational powers, enhancing the integration density alone will not be a solution, because the computational principle in the brain is not yet known. A brain-inspired VLSI architecture based on the associative principle is presented in this paper, in which the non-linear I-V characteristics of nano functional devices are directly utilized as the very bases of computation. The mind processing algorithms are tolerable to elemental-device level variability, thus being most suited to building systems in nanoelectronics.
Effect of the Chemical Oxide Layer Thickness on the Interfacial Quality of ALD-Grown HfO2 on Silicon
Authors: Li Shibin , Chen Zhi D.
Published: April 2010

We report the effects of the thickness variation of the chemical oxide interfacial layer (IL) on the interfacial quality of the HfO2/Si system in this paper. Metal-oxide-semiconductor capacitors using the HfO2/IL gate oxide stack were fabricated using the Ni/Ti metal gate. The capacitance-voltage (C-V) and ellipsometry measurements suggest that the chemical oxide interfacial layer of ~0.45 nm is the minimum requirement for atomic layer deposition (ALD) growth of high quality HfO2 on silicon and thicker chemical oxide interfacial layers (>0.45 nm) result in better interfaces for HfO2 MOS structures with EOTs of < 1 nm.
A Comparison of O3 and H2O as Oxygen Sources for Atomic Layer Deposition Processing of HfAlOx Thin Films for High-k Dielectric Nanocapacitor Applications
Authors: Phillips Richard , Eisenbraun Eric
Published: April 2010

A comparative study of O3 and H2O as oxidizers for atomic layer deposition (ALD) HfOx and AlOx thin films was carried out employing a 300-mm wafer capable ALD cluster tool. TEMAHf (tetrakis-ethylmethylamino-hafnium) and TMA (trimethyl-aluminium) were used as metal precursors. Process conditions were varied to evaluate the effects on unary metal oxide growth as an approach towards developing a mixed-phase binary metal oxide growth process. Films were characterized using scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), Rutherford backscattering spectroscopy (RBS), and capacitance measurements of MOS capacitor structures. Initial testing results of the electrical properties of resulting binary metal oxides will be discussed.
Design of a Novel Wet-Etch Reactor and Etch Chemistries: Simulations and Experimental Verification
Authors: Pande Ashish , Levitin Galit , Mui David S. , Hess Dennis
Published: April 2010

Dilute aqueous solutions of hydrofluoric acid (HF) have been used to etch or remove SiO¬¬2-based layers. Due to the various chemical equilibria established between ionic species in aqueous HF solutions, control of etchant species concentrations and thus etch selectivity is difficult. A short contact time prototype reactor for wet etching studies of silicon-based dielectric films has been designed to investigate the effects of various process parameters during the etch process . For comparison, simulations using Computational Fluid Dynamics (CFD) have been used to predict the effect of process parameters such as flow rates and HF concentrations, thermodynamic equilibria, species transport, intrinsic etch kinetics and geometric parameters of the reactor. Results from CFD and etch experiments are in good agreement. Non-aqueous solutions utilizing fluorine-containing tetrabutylammonium salts have been investigated to control desirable equilibria and tailor etch rates and selectivity.
Modulation of the Electrical Characteristics of HfOx/TiN RRAM Devices Through the Top Electrode Metal
Authors: Chang Kow-Ming , Tzeng Wen-Hsien , Liu Kou-Chen , Lai Wei-Ren
Published: April 2010

The effect of the top electrode on switching characteristics of a HfOx/TiN structure was investigated. From the electrical conduction analysis, the conduction mechanism between Pt and Ti was found to be quite different. A potential barrier formed in the Pt/HfOx interface showing the Fowler-Nordheim tunneling at high bias. However, it was not observed in the Ti/HfOx structure. Reactive metal Ti interacted with the underlying HfOx film leading to destruction of the barrier height. As such, the device lost the ability to operate at the μA compliance current range. Pt/HfOx demonstrated the merit of a large resistance ratio and a low operation current (Ireset = 20 μA). However, Ti/HfOx exhibited better voltage dispersion at the low resistance state (0.5V dispersion). The electrode plays a dominant role in determining the electrical characteristics of a resistive random access memory (RRAM) device. Therefore, choosing an adequate electrode for RRAM is an important consideration.
(Invited) Study on Chemical Bonding States of High-k Gate Stacks for Advanced CMOS
Authors: Nohira Hiroshi
Published: April 2010

The paper reviews the non-destructive depth profiling of the composition and the chemical structure of high-k/Si using angle-resolved photoelectron spectroscopy. Analyses of Si 2s spectra show that the reactivity between ScOx or CeOx and Si substrate is lower than that between LaOx and Si substrate. Analyses of Ce 3d5/2 and O 1s spectra show that a oxidation state of Ce changes from Ce4+ to Ce3+ by PDA in N2 at and above 400{degree sign}C and changes from Ce3+ to Ce4+ by PDA in O2 at 300{degree sign}C. This implies that a oxidation state of Ce can be controlled by changing the condition of PDA. The hard X-ray(hv = 8 keV) excited ARXPS study on high-k/Si structure show that the existence of La-silicate accelerates the formation of La-silicate by PDA.
(Invited) Oxidation, Diffusion and Desorption in a Ge/GeO2 System
Authors: Toriumi Akira , Wang Shengkai , Lee Choong-Hyun , Yoshida Mahoro , Kita Koji , Nishimura Tomonori , Nagashio Kosuke
Published: April 2010

The effects of oxidation, diffusion, and desorption in a Ge/GeO2 system on the Ge/GeO2 stack formation process for Ge-CMOS are discussed. The GeO desorption is a key to understanding and to establishing the Ge gate stack formation process. High-pressure O2 oxidation has dramatically improved Ge/GeO2 MIS capacitors. This aspect of gate stack formation in Ge is quite different from that in Si.
Effect of Processing Conditions on the Electrical Characteristics of Atomic Layer Deposited Al2O3 and HfO2 Films
Authors: Rafí Joan Marc , Zabala Miguel , Beldarrain Oihane , Campabadal Francesca
Published: April 2010

An extensive mercury-probe capacitance-voltage characterization is carried out on Al2O3 and HfO2 films deposited on silicon by atomic layer deposition (ALD) at different temperatures and subjected to various high-temperature post-deposition thermal treatments. For the case of the Al2O3 layers, higher flat-band voltages (Vfb) for higher deposition temperatures are obtained and positive Vfb shifts are always registered after the different thermal annealing conditions studied; however, the impact is found to be significantly different depending on the deposition temperature. On the contrary, smaller changes are observed for the case of the studied HfO2 layers. Interestingly for practical applications, the hystereses, as well as the Vfb shifts, clearly diminish for higher deposition temperatures or after a thermal annealing treatment. The results obtained from ellipsometry suggest that significant physical changes occur under the highest temperature treatments in either, the ALD Al2O3 or HfO2 layers and/or its interface with the silicon substrate.
(Invited) Charge Pumping and Si-SiO2 Interface Traps Electrical Characterization
Authors: Bauza D.
Published: April 2010

After recalling recent results obtained in the field of the electrical characterization of the Si-SiO2 interface traps in conventional MOS transistors and in MOSFET's having HfO2 as gate dielectric using the charge pumping (CP) technique, the paper focuses on the slope of the CP curves.
(Invited) Degradation in MOSFET Multistack High-k Gate Dielectrics Due to Hot Carrier and Constant Voltage Stress
Authors: C¸elik-Butler Zeynep , Rahman Shahriar
Published: April 2010

Hafnium based materials are the leading high dielectric constant (high-k) candidates to replace conventional SiO2 and SiON as the gate dielectric in complementary metal-oxide-semiconductor (CMOS) devices for sub-45nm technology nodes. To explain the low frequency noise behavior in these gate dielectrics, a new model is required that can take care of various material properties and new structures. In this paper, a new low frequency noise model for high-k gate materials as well as various stress-induced noise degradation are presented. The additional, stress-induced low-frequency noise was evaluated on nMOSFETs with TiN metal gate and HfSiON gate dielectric. Nitridation of HfSiO was achieved either by high temperature thermal nitridation or by relatively lower temperature plasma nitridation. The difference in stress-induced noise behavior is attributed to the nitrogen profile across the gate dielectric/Si interface and the bulk of the high-k gate oxide caused by different nitridation techniques.
(Invited) Advanced FinFET Technologies: Extension Doping, Vth Controllable CMOS Inverters and SRAM
Authors: Liu Yongxun , Endo Kazuhiko , O'uchi Shinichi , Matsukawa Takashi , Sakamoto Kunihiro , Masahara Meishoku
Published: April 2010

The advanced FinFET technologies including extension doping, threshold voltage controllable CMOS inverters and the b-ratio optimized SRAMs are presented. It is experimentally found that the best extension ion implantation conditions are dose of 4x1014 cm-2 and tilted angle of 60o. With further increasing dose, the device performance deteriorates owing to the incomplete recrystallization of amorphous regions in the thin extensions. The logic gate threshold voltage controllable single metal gate FinFET CMOS inverter constructed by a tied-gate 3-terminal (3T) PMOS and an independent double-gate 4-terminal (4T) NMOS is proposed and demonstrated. Furthermore, the FinFET SRAMs with different b-ratios were fabricated and evaluated. The higher b-ratio provides the large static noise margin at read condition due to the high current drivability of pull-down transistor.