bluuebunny/crossref_metadata_2025_split huggingface dataset:
A numerical study of wave structures developed on the free surface of a film flowing on inclined planes and subjected to surface shear
Authors: Shuaib N. H. , Power H. , Hibberd S. , Simmons K. 
Published: April 2006

AbstractIn this work, we determine the different patterns of possible wave structures that can be observed on a thin film flowing on an inclined plane when at the free surface a shear force (surface traction) is applied. Different wave structures are obtained dependening on the selected combination of downstream and upstream boundary conditions and initial conditions. The resulting initial boundary value problems are solved numerically using the direct BEM numerical solution of the complete two‐dimensional Stokes system of equations. In our numerical results, the initial discontinuous shock profiles joining uniform fluid depths are smoothed due to the two‐dimensional character of the Stokes formulation, including the effect of the gravitational force as well as the interfacial surface tension force. In this way, physically feasible continuous surface profiles are determined, in which the initial uniform depths are joined by smooth moving wave structures. Numerical solutions have been attained to reproduce the different patterns of possible wave structures previously reported in the literature and extended to identify some other new structures and features defining the behaviour of the surface patterns. Copyright © 2006 John Wiley & Sons, Ltd.
On the enforcing energy conservation of time‐finite elements for particle systems
Authors: Bui Q. V. 
Published: April 2006

AbstractIn the framework of the time‐finite element method, energy‐conserving temporal integrators are developed through the design of non‐standard quadrature. The latter can be achieved by a global enforcement of the force field issued from the standard quadrature. This might, however, lead to an undesirable coupling of all degrees of freedom. A local enforcement is suggested to enhance the enforcement of energy conservation through a tailored modification to each component of acting forces. Representative examples for non‐linear particle systems are presented in order to examine the quality of various approaches in the enforcement of energy conservation. Copyright © 2006 John Wiley & Sons, Ltd.
Scale‐related topology optimization of cellular materials and structures
Authors: Zhang Weihong , Sun Shiping 
Published: April 2006

AbstractThe integrated optimization of lightweight cellular materials and structures are discussed in this paper. By analysing the basic features of such a two‐scale problem, it is shown that the optimal solution strongly depends upon the scale effect modelling of the periodic microstructure of material unit cell (MUC), i.e. the so‐called representative volume element (RVE). However, with the asymptotic homogenization method used widely in actual topology optimization procedure, effective material properties predicted can give rise to limit values depending upon only volume fractions of solid phases, properties and spatial distribution of constituents in the microstructure regardless of scale effect. From this consideration, we propose the design element (DE) concept being able to deal with conventional designs of materials and structures in a unified way. By changing the scale and aspect ratio of the DE, scale‐related effects of materials and structures are well revealed and distinguished in the final results of optimal design patterns. To illustrate the proposed approach, numerical design problems of 2D layered structures with cellular core are investigated. Copyright © 2006 John Wiley & Sons, Ltd.
Selective binding and enrichment for low‐molecular weight biomarker molecules in human plasma after exposure to nanoporous silica particles
Authors: Terracciano Rosa , Gaspari Marco , Testa Flaviano , Pasqua Luigi , Tagliaferri Pierosandro , Cheng Mark Ming‐Cheng , Nijdam A. Jasper , Petricoin Emanuel F. , Liotta Lance A. , Cuda Giovanni , Ferrari Mauro , Venuta Salvatore 
Published: April 2006

AbstractThe present manuscript describes a biomarker capturing strategy based on nanoporous silica particles. The method is shown to enrich the yield of species in the low‐molecular weight proteome (LMWP), allowing detection of small peptides in the low‐nanomolar range. Plasma samples were exposed to the silica particles, and the captured molecular species were profiled using MALDI‐TOF. Mass spectra of the silica‐treated human plasma samples showed a significant enrichment in MALDI‐TOF protein profiles in the LMWP. Preliminary results indicated good level of reproducibility in plasma profiles with CVs on peak heights ranging from 6.3 to 14.7%. The MALDI‐TOF signature changed significantly when the characteristics of the nanoporous silica were altered. The facile sample pretreatment before MS analysis, coupled to the potential for tailoring the surface properties of silica supports, hold promise for improving the recovery of low‐abundance serum biomarkers.
Preparation of SiO2/PMMA composite particles via conventional emulsion polymerization
Authors: Cheng Xinjian , Chen Min , Zhou Shuxue , Wu Limin 
Published: April 2006

AbstractA series of SiO2/PMMA composite particles with different morphologies were prepared by conventional emulsion polymerization by the aid of acid–base interaction between the silanol groups of unmodified silica particles and the amino groups of 4‐vinylpyridine. In this approach, no surface treatment for nanosilica particles was required. The morphologies of composite particles, for example, multicore–shell, raspberry‐like, and conventional core–shell, could be controlled by modulating emulsifier content, monomer/silica ratio, silica size, and monomer feed method. The possible particle formation mechanisms were discussed. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3807–3816, 2006
Optimization strategies for segmented Peltier coolers
Authors: Müller Eckhard , Walczak Steven , Seifert Wolfgang 
Published: April 2006

AbstractCommercialisation of Peltier coolers has progressed during last years and special efforts have been undertaken to enhance the efficiency of thermoelectric (TE) devices. Along with the continued search for advanced TE materials, the concept of functionally graded materials (FGM) offers a pathway to gradual improvement of device performance. Starting from the first principles of thermoelectricity in a 1D approach, a differential equation governing the coupling of thermal and electrical transports is applied here for modelling multi‐segment Peltier cooling elements within the framework of a constant parameters theory.With the constant material properties values in each segment representing volume average values of spatially varying non‐constant profiles, this model provides an approximation of excellent accuracy also for continuously graded elements. The work presents parameter studies on segmented Peltier elements based on material parameters close to real data thus revealing strategies for optimal design. As target parameters, the maximum C.O.P., maximum cooling power, and the maximum temperature difference have been determined for various shapes of gradients. Tendencies for favourite gradients of the Seebeck coefficient and the electrical conductivity have been found. Example calculations for a material withZT≈ 1 show an enhancement of the maximum temperature difference by up to 15% (13 K). (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic domain walls at the edge of patterned NiO/NiFe bilayers
Authors: Kim S. W. , Lee S. S. , Gomez R. D. , Hahn E. J. , Hwang D. G. 
Published: April 2006

AbstractThe magnetic domain walls at the edges of a large patterned and exchange‐biased NiO (10–60 nm)/NiFe (10 nm) bilayers and their motions with applied field were investigated by MFM. Three kinds of domain walls were found at the edges of the NiO (30 nm)/NiFe (10 nm) bilayer having the exchange biasing field (Hex) of 21 Oe. Two zigzag charged walls and Néel wall appeared at the edges perpendicular and parallel to Hex, respectively. The zigzag charged walls are nearly a factor of three wider than the Néel wall, and were not observed for the strong exchange‐biased bilayer (60 nm NiO, H ex = 75 Oe). We investigated the subsequent motion of the walls, and identified the pinning and nucleation sites during magnetization reversal. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Preparation of inorganic–organic hybrid titania sol–gel nanocomposite films, and their dielectric properties
Authors: Kim Hoon , Pramanik Nimai Chand , Ahn Bok Yeop , Seok Sang Il 
Published: April 2006

AbstractHybrid titania materials were prepared by a process involving the phase separation of TiO2 by hydrolysis and polycondensation from hybrids between titanium tetraisopropoxide (TTIP) and 3‐(methacryloyloxy)propyl trimethoxysilane (MPTS) with excess acidic water at an elevated temperature (80 °C). The formation of TiO2 nanoparticles within the hybrid materials was studied as a function of the ageing time as well as the Ti/Si molar ratio. The crystalline phases of the TiO2 nanoparticles formed in situ within the inorganic–organic hybrid matrix were characterized by X‐ray diffraction and Fourier transform infrared studies. The microstructures and the morphologies of thick films of the hybrid materials were studied using scanning and transmission electron microscopy, which showed the existence of nanocrystalline TiO2 within the crack‐free hybrid matrix. The dielectric constants of the composites were found to be in the range 5.0–7.1, depending on the measuring frequency and the composite composition. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Role of interfaces on the direct tunneling and the inelastic tunneling behaviors through metal/alkylsilane/silicon junctions
Authors: Aswal D. K. , Petit C. , Salace G. , Guérin D. , Lenfant S. , Yakhmi J. V. , Vuillaume D. 
Published: April 2006

AbstractWe studied the influence of the end group of the alkylsilane molecule used in Self Assembled Monolayer (SAM) in Silicon/SAM/Metal junctions. By Inelastic Electron Tunneling spectroscopy (IETS), we showed the formation of a covalent bond between the molecules and the gold electrode in the case of a thiol terminated alkylsilane. By electrical characterizations, we demonstrated that the thiol group at the interface avoids diffusion of gold into the molecule even for a 3 carbons chain. For this short molecule, we observed pure tunnel conduction with barrier height at the monolayer/Si and monolayer/Au interfaces found to be respectively 2.14 and 2.56 eV. These values were obtained using Simmons equation with an effective mass parameter m * = 0.16m e (m e = mass of the electron).This extends the demonstration of the excellent tunnel dielectric behavior of these organic monolayers down to 3 carbon atoms with a thiol/Au bond at the interface. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of matrix defects on the photoluminescence of InAs self‐assembled quantum dots
Authors: Chahboun A. , Baidus N. V. , Demina P. B. , Zvonkov B. N. , Gomes M. J. M. , Cavaco A. , Sobolev N. A. , Carmo M. C. , Vasilevskiy M. I. 
Published: April 2006

AbstractWe report the effect of defects that appear during capping layer growth or are introduced intentionally, on the photoluminescence (PL) properties of InAs strained quantum dots. A treatment of the samples with CCl4 during the growth leads to the reduction of native defect concentration in the GaAs matrix. This is shown to improve the emission intensity and to remove the quenching effect at room temperature. Some samples were subjected to proton irradiation in order to generate more defects in the matrix. The comparison between the emission from as‐grown samples and irradiated ones shows a decrease of the PL intensity with the irradiation dose. However, no change in the activation energy for carrier's thermal escape was observed. The deterioration of the emission properties with the increasing irradiation dose is probably related to traps generated by the irradiation in the matrix, which reduce the overall concentration of the photocarriers. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Density functionals and half‐metallicity in La2/3Sr1/3MnO3
Authors: Ferrari V. , Pruneda J. M. , Artacho Emilio 
Published: April 2006

AbstractThe electronic structure and equilibrium geometry of La2/3Sr1/3MnO3 are studied theoretically by means of density functional calculations. The doping is treated by introducing holes and a compensating jellium background. The results for the local density approximation (LDA) agree with previous LDA calculations, with an equilibrium volume 5.3% too small and with both majority and minority spin states present at the Fermi level for the relaxed system. The generalised gradient approximation (GGA) offers a qualitatively improved description of the system, with a more realistic volume, and a half‐metallic behaviour for the relaxed structure, which enables studies needing theoretical relaxation. The ideal MnO2‐terminated (001) surface is then described with explicit doping. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Symmetry breaking and Wigner molecules in few‐electron quantum dots
Authors: Yannouleas Constantine , Landman Uzi 
Published: April 2006

AbstractWe discuss symmetry breaking in two‐dimensional quantum dots resulting from strong interelectron repulsion relative to the zero‐point kinetic energy associated with the confining potential. Such symmetry breaking leads to the emergence of crystalline arrangements of electrons in the dot. The so‐called Wigner molecules form already at field‐free conditions. The appearance of rotating Wigner molecules in circular dots under high magnetic field, and their relation to magic angular momenta and quantum‐Hall‐effect fractional fillings is also discussed. Recent calculations for two electrons in an elliptic quantum dot, using exact diagonalization and an approximate generalized‐Heitler–London treatment, show that the electrons can localize and form a molecular dimer for screened interelectron repulsion. The calculated singlet‐triplet splitting (J ) as a function of the magnetic field (B ) agrees with cotunneling measurements; its behavior reflects the effective dissociation of the dimer for large B . Knowledge of the dot shape and of J (B ) allows determination of two measures of entanglement (concurrence and von Neumann entropy for indistinguishable fermions), whose behavior correlates also with the dissociation of the dimer. The theoretical value for the concurrence at B = 0 agrees with the experimental estimates. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Charting Biological and Chemical Space: PSSC and SCONP as Guiding Principles for the Development of Compound Collections Based on Natural Product Scaffolds
Authors: Arve Lars , Voigt Tobias , Waldmann Herbert 
Published: April 2006

AbstractFinding small molecules that selectively modulate protein function remains one of the major challenges in the fields of chemogenomics and drug development. Natural products interact with proteins in their biosynthesis and when displaying biological activity, and can therefore be considered as “privileged structures”. Thus, natural products may serve as biologically validated starting points for the design of focused compound collections. In recent years, effective synthesis methods for natural‐product‐based focused compound collections have been developed, including multi‐component reactions. This review discusses recent advances in the synthesis of natural‐product‐inspired compound collections as well as the application of Protein Structure Similarity Clustering (PSSC) and a Structural Classification Of Natural Products (SCONP) as guiding principles for the design of focused compound collections based on natural products.
Differences in beech (Faguscrenata) regeneration between two types of Japanese beech forest and along a snow gradient
Authors: Shimano Koji 
Published: April 2006

AbstractDifferences in beech (Fagus crenata) regeneration were quantitatively investigated using power function analysis for the size–class (diameter at breast height, DBH) distribution and juvenile‐to‐canopy tree (J/C) ratio along a snow gradient throughout Japan. In snowy areas, all species combined, as well as F. crenata alone, showed constant regeneration, with parameter b≈−1.6 for the power function y=axb (x=DBH, y=density), which is related to the DBH–class distribution. The good fit of the data to the function suggests that beech regenerates constantly with self‐thinning patch dynamics. Parameter a, which indicates the abundance of small trunks, was high. Furthermore, the mean J/C ratio was ≈8, i.e., each parent beech tree produced eight juveniles. These results suggest that beech regenerates constantly with gap dynamics in snowy beech forests on the Japan Sea side of Japan (snowy). However, the fit of F. crenata was lower and nonsignificant in some forests in less snowy areas, despite the high fit of all species combined. In these areas, the mean of a was low, and b was often near zero for F. crenata regressions. These results suggest that the abundance of beech was low, and self‐thinning was not evident because of the initial low abundance. Moreover, the mean J/C ratio was <1.0, suggesting that juvenile density was lower than that of canopy trees. Thus, the regeneration of F. crenata on the Pacific Ocean side of Japan (less snowy) is rather sporadic. Less snowy conditions may promote seed desiccation, predation of beechnuts and seedlings, and water stress. Lower F. crenata density may also reduce predator satiation and wind pollination.
A Novel Method for the Quantitative Evaluation of Lumbar Spinal Stenosis
Authors: Zheng Fengyu , Farmer James C. , Sandhu Harvinder S. , O'Leary Patrick F. 
Published: April 2006

Study design A retrospective study of computed tomography (CT) myelographic images in patients with degenerative lumbar spinal stenosis (LSS). Objectives To introduce a new technique for the quantitative evaluation of LSS. Background Advances in hardware and software technology now permit inexpensive digitalization of radiological images, and enable methodologies for quantifying space available for neural elements in spinal canal. However, a valid method with quantitative evaluation of spinal stenosis in living patients has not been developed yet. Methods and materials Preoperative CT myelographic scans of 50 patients with degenerative LSS were collected for retrospective investigation. The patients subsequently underwent lumbar decompressive surgery. They included scans from thoracic vertebra 12 (T12) to sacrum (S1), in which each segment was scanned through both the vertebral body and disk. All CT scan films were digitized using a high-resolution digital camera. ImageTool™ software was used to measure three parameters: cross-sectional area of dural sac at disk level (A), cross-sectional area of spinal canal at midpedicular level (B), and cross-sectional area of vertebral body (C). The dural sac canal ratio (DSCR) was calculated as A/ B×100%. Low DSCR implied severe dural sac compression with a high degree of stenosis. The spinal canal vertebral ratio (CVR) was also calculated as B/ C×100%. Low CVR implied a low baseline of canal capacity for neural elements. They were calculated from T12 to S1. Results The study consisted of 26 male and 24 female patients, with an average age of 68.4 (35–97) years. A total of 295 segments were evaluated, of which 118 (40%) were surgically decompressed. There were wide ranges of canal cross-sectional areas (140–475 mm2) and dural sac cross-sectional area (54–435 mm2). Male patients had a slightly larger canal cross-sectional area than female patients at each level. The mean CVR was found decreased from T12 (26.1%) to L4 (18.3%). This was higher in female than in male patients, especially from T12 to L2 ( P < 0.01). There were significant correlations between spinal canal and dural sac cross-sectional area ( r = 0.55, P < 0.001), and also between CVR and DSCR ( r = 0.31, P < 0.001). Of the levels decompressed, 82% was performed from the level L2 to L5, in which there was no significant difference in canal cross-sectional area and CVR between decompression and nondecompression ( P > 0.05). There was a good correspondence between decreasing mean DSCR and increasing percentile of levels decompressed. Conclusion DSCR represents a useful method for the quantitative diagnosis of lumbar spinal canal stenosis. ImageTool™ software is a useful tool in measuring spinal morphometry.
The benefits of expediting government gold sales
Authors: Henderson Dale W. , Salant Stephen W. , Irons John S. , Thomas Sebastian 
Published: April 2006

AbstractAdditional gold can be made available either by mining at high cost (approximately $250 per ounce in 1997 dollars) or by mobilizing government stocks at zero cost. Governments own massive above‐ground stocks but loan out only a small percentage of these stocks. Making all government gold available for private uses immediately through some combination of sales and loans maximizes total welfare from private uses, a consequence of the first welfare theorem. We simulate a calibrated version of our model to quantify the effects of liquidating government stocks on alternative dates. If governments sell immediately rather than never, total welfare increases by $340 billion; if they make an unanticipated sale in 20 years, $105 billion of that amount is lost. By depressing prices, such sales benefit depletion and service users but injure private owners of stocks above and below‐ground. However, the injury to above‐ground stock owners is more than offset by the benefits to service users—often the same individuals. Mine owners would be the principal losers; however, they could be compensated (twice over) from government sales revenue without any need for tax increases.
On the origin of wave patterns in fluidized beds
Authors: Göz M. F. 
Published: April 2006

In this report, a model designed for the description of the flow of two miscible phases in a fluidized bed is discussed. Apart from basic problems of modelling accurately such multi-phase flows, little analytical progress had been achieved in the investigation of a certain standard model based on the theory of interacting continua. It turns out, however, that the model under consideration can be investigated with the help of bifurcation theory. In particular, the methods of the theory of bifurcation with symmetry can be applied owing to the symmetries of the system.In general, a stationary homogeneous state exists in fluidized beds which can become unstable when the physical parameters of the system are varied. Then pattern formation takes place, e.g. in the form of one- and/or two-dimensional waves, bubbles, or convection patterns; also turbulent behaviour has been observed.In order to understand the occurrence of wave patterns and other phenomena as an inherent feature of the system, a finite, but periodically continued two-dimensional bed is investigated. While this suppresses certain boundary effects, it gives us thorough insight into the principal behaviour of this complicated system.In particular, it allows us not only to perform easily a linear stability analysis of the basic state of uniform fluidization, but also to conclude that bifurcation of travelling waves occurs when this state becomes unstable. Well-known patterns like vertical and oblique travelling waves (OTW) of the form $u(x,y,t) = \tilde{u}(x-\omega t\pm ky)$, k [ges ] 0, are discovered. Owing to symmetry, the existence of standing travelling waves (STW) of the form $u(x,y,t) = \tilde{u}(x-\omega t, y)$ is also expected, but regrettably no mathematically rigorous proof of this last conjecture is presently available.Bubble formation can also be approached via the instability of a vertical travelling plane wave train to transverse perturbations. Then a secondary stationary bifurcation to another kind of standing travelling waves takes place. This scenario is also in agreement with experimental observations. In addition, the occurrence of bifurcations of higher order, which lead to more and more complex wave patterns and are to be found on the route to turbulence, can be deduced.