bluuebunny/crossref_metadata_2025_split huggingface dataset:
Linking PCA and time derivatives of dynamic systems
Authors: Stanimirovic Olja , Hoefsloot Huub C. J. , de Bokx Pieter K. , Smilde Age K. 
Published: January 2007

AbstractLow dimensional approximate descriptions of the high dimensional phase space of dynamic processes are very useful. Principal component analysis (PCA) is the most used technique to find the low dimensional subspace of interest. Here, it will be shown that mean centering of the process data across time followed by PCA yields valuable information about the time derivatives of the model function underlying the data. The advantage of PCA is that it can be used when the process model is not (fully) known and enough process measurements are available. The idea is illustrated with an example of a distributed parameter system. More specifically, the binary adsorption of benzene and toluene on charcoal in a packed bed filter for air cleaning is considered. It is shown that with the information gained about time derivatives, sensor locations for monitoring this process can be found. Copyright © 2007 John Wiley & Sons, Ltd.
Proposal of 98.5% high‐efficiency chopper circuit QRAS for the electric vehicle and the verification
Authors: Tsuruta Yukinori , Kawamura Atsuo 
Published: January 2007

AbstractA high‐efficiency and high‐power chopper based on a novel soft switching scheme QRAS (Quasi‐resonant Regenerating Active Snubber) has been proposed in this paper. Operating efficiency of the proposed QRAS has been investigated by simulation and experiments. For the purposes of this study we fabricated a one‐tenth prototype model and tested it under the rated load, light load, current discontinuous mode, and under operation out of the resonant stable operational region. The overall evaluation of these test results is provided and the possibility of implementation of an 80‐kW practical model is demonstrated by these successful test results. In addition, as an approach to the next study, the feasibility of 8‐kW SiC‐QRAS is examined and a preliminary evaluation of the efficiency enhancement due to the use of silicon carbide (SiC) power devices is given based on successful experimental results. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 158(4): 68– 80, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20439
Finding optimal SVR placement in distribution systems using power density model
Authors: Kubota Yoshiyuki , Genji Takamu 
Published: January 2007

AbstractIn long distribution systems, Step Voltage Regulators (SVRs) are installed to regulate the system voltage. There are some papers on finding optimal placements of SVRs in the system. However, there is no analytic method that focuses on the voltage margin, that is, the optimal placement with respect to the system voltage.The authors propose a method of finding the placement of an SVR so that the voltage margin from the upper (or lower) voltage limit is the largest under heavy load.In order to deal with sets of loads that are dispersed over the entire distribution line, we derive the differential equation of the complex power and that of the voltage drop, which are expressed as functions of distance from a substation. The voltage profile is obtained as a cubic equation by solving the voltage equation if the load distribution is trapezoidal. The method of finding the optimal SVR placement distinguishes three modes with three different voltage profiles. One is the case in which the transformation ratio of the SVR is small and the system length is short, one is the case in which the transformation ratio of the SVR is large and the system length is short, and the third is the case in which the transformation ratio of the SVR is large and the system length is long. The optimal placement and tap position of the SVR are calculated by solving the above‐mentioned equations in these three modes.It is confirmed that the proposed analytical method is appropriate by model calculation results. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 158(4): 11–21, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20481
Voltammetric Characterization and Amperometric Detection of β‐Carboline Alkaloids at Carbon Nanotube‐Modified Electrodes
Authors: Agüí L. , Peña‐Farfal C. , Yáñez‐Sedeño P. , Pingarrón J. M. 
Published: January 2007

AbstractThe voltammetric behavior of β‐carboline alkaloids at carbon nanotubes‐modified glassy carbon electrodes, as well as their quantification by amperometric monitoring of the oxidation responses, are reported. Cyclic voltammograms of harmane, harmine, harmaline and harmalol at the CNT‐GCE showed enhanced voltammetric responses with respect to those obtained at a bare GCE. The effect of pH on the oxidation ip and Ep values obtained by differential pulse voltammetry was discussed, as well as their mechanistic aspects. Hydrodynamic voltammogram of these compounds led us to select a potential value of +900 mV for their amperometric detection. Under these conditions, no fouling of the modified electrode surface is evidenced. The HPLC separation and determination of β‐carboline alkaloids were carried out using a mobile phase consisting of 20% (v/v) methanol‐20% (v/v) acetonitrile‐0.05 mol L−1 HPO solution of pH 9.0. Detection limits ranging between 28 nM (harmalol) and 88 nM (harmaline) were achieved. The usefulness of the chromatographic method with amperometric detection at the CNT‐GCE was demonstrated by analyzing soy seeds samples spiked with harmaline, harmane and harmine at a 0.25 μg/g level.
Voltammetric Peak Area as Instrumental Datum. A Possibility to Improve the Determination at Ultratrace Level Concentration of Platinum Group Metals (PGMs) and Lead. Application to Particulate Matter
Authors: Locatelli Clinio 
Published: January 2007

AbstractPeak area as instrumental datum for determining the concentration of metals in solution instead of peak height is proposed for analytical voltammetric determinations. In the case of species present at ultratrace concentration level or having low reversibility degree of the electrodic processes, the employment of peak area permits to achieve limits of detection lower even more of one order of magnitude. The present work shows the possibility of determining at ultratrace level concentration Pd(II), Pt(II), Rh(III) and Pb(II) by voltammetry in particulate matter; these species, linked to vehicle emissions, show to have, in the supporting electrolytes employed, a very high irreversibility degree of the electrodic processes.
The effect of enzymatically degradable IPN coatings on peri‐implant bone formation and implant fixation
Authors: Ho James E. , Barber Thomas A. , Virdi Amarjit S. , Sumner Dale R. , Healy Kevin E. 
Published: January 2007

AbstractShort‐term osseointegration of orthopedic implants is critical for the long‐term stability of the implant–bone interface. To improve initial implant stability, one strategy under consideration involves the presentation of adhesion ligands on the implant surface to stimulate bone regeneration in the peri‐implant region. To assess the relative effects of implant surface chemistry and topography on osseointegration within the rat femoral ablation implant model, a nonfouling, enzymatically degradable interpenetrating polymer network (edIPN) of poly(AAm‐co‐EG/AAc) amenable to presenting the cell signaling domain Arg‐Gly‐Asp (RGD), was developed. Moderate enhancement of peri‐implant bone formation was found after 28 days using the edIPN without peptide modification (p = 0.032). However, no data supported a benefit of peptide modification, as bone–implant contact, normalized bone volume and normalized fixation strength was equivalent or poorer than dual acid‐etched (DAE) treated implants after 28 days. Surface topography was determined to be the dominant factor in modulating osseointegration, as DAE implants produced equivalent roughness‐normalized fixation strength versus previously reported data on plasma‐sprayed hydroxyapatite/tricalcium phosphate‐coated implants (Barber et al., J Biomed Mater Res A, forthcoming). An ideal osseointegrated implant will require optimization of all three aforementioned parameters, and may take the form of biomolecule delivery from thin degradable polymer networks. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Shape‐engineered vascular endothelial cells: Nitric oxide production, cell elasticity, and actin cytoskeletal features
Authors: Kidoaki Satoru , Matsuda Takehisa 
Published: January 2007

AbstractSingle cell shape determines cellular functions. Therefore, control of cell shape is of considerable importance for the tissue engineering field. This study was designed to assess the effect of surface‐induced shaping of vascular endothelial cells (ECs) on the intracellular nitric oxide (NO) production level, the cell elasticity, and cytoskeletal (CSK) features on shape‐engineered ECs (round, 90, 120 μm diameter; spindle‐shaped, 20, 30, 40 μm width) prepared on a photolithographically microprocessed surface. Intracellular NO production was measured using a microscopic spectrometer with diaminofluorescein diacetate probe. Cell elasticity and actin CSK features were analyzed through microindentation measurement and fluorescence observations with fluorescence and atomic force microscopy. Results showed that spindle‐shaped cells exhibited lower NO production, higher cell stiffness, and denser actin stress fibers than the round and nonrestrictedly cultured control cells. Relations between cell shape with NO production, cell elasticity, and actin CSK features were discussed. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Ennoblement of stainless steel in natural seawater – A new explanation
Authors: Xiangbo L. , Jia W. , Wei W. , Hongren W. 
Published: January 2007

AbstractThe ennoblement of corrosion potential (Ecorr) of passive metal immersed in seawater was investigated with electrochemical technology and epifluorescence microscopy. The in situ observation showed that the bacteria number increased on the metal surface according to an exponential law which was in the same way with the ennoblement of Ecorr. At the same time, the anodic polarization current of high‐Mo stainless steel decreased in the initial days. According to the mix‐potential theory and the characteristics of polarization curves of high‐Mo steel in natural seawater, the ennoblement of corrosion potential may be induced by the decrease of the passive current density.
A SERS investigation of carbon steel in contact with aqueous solutions containing BenzylDiMethylPhenylAmmonium Chloride
Authors: Bozzini B. , Romanello V. , Mele C. , Bogani F. 
Published: January 2007

AbstractThe electrochemical behaviour of carbon steel in contact with a neutral sulphate solution containing BenzylDiMethylPhenylAmmonium Chloride (BDMPAC), a potential non‐toxic corrosion inhibitor was investigated by Surface Enhanced Raman Spectroscopy (SERS) and linear sweep voltammetry. Sound surface enhancement was obtained by potentiostatic polarisation without special electrochemical pretreatments. Potential‐dependent Raman spectra highlighted the electrodic behaviour of the adsorbate: in the range − 1200 ÷ − 900 mV (Ag/AgCl), adsorption takes place with the benzyl ring interacting with the surface in a flat configuration, as indicated by the presence of the Ph‐CH2 combination band located near 1215 cm−1. Linear sweep voltammetry testifies the difference in measured currents between sulphate containing solutions in the absence and the presence of BDMPAC at the adsorption potentials. The formation of iron corrosion products was easily detected by in situ Raman spectroscopy.
Specification of sulfate reducing bacteria biofilms accumulation effects on corrosion initiation
Authors: Liu H. , Huang L. , Huang Z. , Zheng J. 
Published: January 2007

AbstractThe accumulation process of sulfate reducing bacteria (SRB) biofilms established in anaerobic stagnant batch bioreactors on the surface of carbon steel and the nutrient transport and corrosion products distribution in it were characterized by X‐ray Photoelectron Spectroscopy (XPS). In addition, the corrosion occurrence and development of carbon steel under SRB biofilm was investigated by Electrochemical Impedance Spectroscopy (EIS) in‐situ. The results show that the thickness of SRB biofilms increases exponentially with time in the beginning and after 14 days reaches a maximum. From then on, the accumulation rate decreases to zero. In mature biofilms, SRB dispersed throughout the biofilm. In the inner layer near the substrate, due to the high sulfate‐reducing activity of SRB, corrosion products such S2−, H2S and organic acid are present, which lead to corrosion occurrence and development. In the outer layer of the biofilm SRB can also reduce the SO2−4 to SO2−3 and S2O2−3. This metabolism process enhances the Fe2+ transfer from the inner to the outer side. The activity of SRB in the biofilm plays a key role in the initial corrosion process.
Some estimates for the torsional rigidity of composite rods
Authors: Crasta Graziano , Fragalà Ilaria , Gazzola Filippo 
Published: January 2007

AbstractA well‐known problem in elasticity consists in placing two linearly elastic materials (of different shear moduli) in a given plane domain Ω, so as to maximize the torsional rigidity of the resulting rod; moreover, the proportion of these materials is prescribed. Such a problem may not have a classical solution as the optimal design may contain homogenization regions, where the two materials are mixed in a microscopic scale. Then, the optimal torsional rigidity becomes difficult to compute. In this paper we give some different theoretical upper and lower bounds for the optimal torsional rigidity, and we compare them on some significant domains. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Approximate identities in variable Lp spaces
Authors: Cruz‐Uribe D. , Fiorenza A. 
Published: January 2007

AbstractWe give conditions for the convergence of approximate identities, both pointwise and in norm, in variable L p spaces. We unify and extend results due to Diening [8], Samko [18] and Sharapudinov [19]. As applications, we give criteria for smooth functions to be dense in the variable Sobolev spaces, and we give solutions of the Laplace equation and the heat equation with boundary values in the variable L p spaces. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
KK ‐theory of amalgamated free products of C *‐algebras
Authors: Eliasen Rune 
Published: January 2007

AbstractJ. Cuntz has conjectured the existence of two cyclic six terms exact sequences relating the KK ‐groups of the amalgamated free product A 1 ∗︁ B A 2 to the KK ‐groups of A 1, A 2 and B. First we establish automatic existence of strict and absorbing homomorphisms. Then we use this result to verify the conjecture when B is a countable direct sum of matrix algebras and the embeddings of B into A 1 and A 2 are quasiunital. Inspired by the proof we achieve the following nice classification result: A separable C *‐algebra B is a countable direct sum of matrix algebras if and only if the unitary group of the multiplier algebra U M (B) is compact in the strict topology. Finally we prove the conjecture when the amalgamated free product has the property that any asymptotically split extension of A 1 ∗︁ B A 2 is split. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ample vector bundles and Bordiga surfaces
Authors: Lanteri Antonio , Maeda Hidetoshi 
Published: January 2007

AbstractLet X be a smooth complex projective variety and let Z ⊂ X be a smooth surface, which is the zero locus of a section of an ample vector bundle ℰ of rank dimX – 2 ≥ 2 on X. Let H be an ample line bundle on X, whose restriction H Z to Z is a very ample line bundle and assume that (Z, H Z ) is a Bordiga surface, i.e., a rational surface having (ℙ2, 𝕆 (4)) as its minimal adjunction theoretic reduction. Triplets (X, ℰ, H) as above are discussed and classified. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Primary lateral sclerosis
Authors: Singer Mike A. , Statland Jeffrey M. , Wolfe Gil I. , Barohn Richard J. 
Published: January 2007

AbstractThe spectrum of motor neuron diseases ranges from disorders that clinically are limited to lower motor neurons to those that exclusively affect upper motor neurons. Primary lateral sclerosis (PLS) is the designation for the syndrome of progressive upper motor neuron dysfunction when no other etiology is identified. Distinction between PLS and the more common amyotrophic lateral sclerosis (ALS) relies primarily on recognition of their symptoms and signs, as well as on ancillary, although non‐specific, laboratory data. In this review, we survey the history of PLS from the initial descriptions to the present. We discuss the role of laboratory, electrodiagnostic, and imaging studies in excluding other diagnoses; the findings from major case series of PLS patients; and proposed diagnostic criteria. Consistent differences are evident in patients classified as PLS compared to those with ALS, indicating that, despite its limitations, this clinical designation retains important utility. Muscle Nerve, 2007
1H NMR metabonomics of plasma lipoprotein subclasses: elucidation of metabolic clustering by self‐organising maps
Authors: Suna Teemu , Salminen Aino , Soininen Pasi , Laatikainen Reino , Ingman Petri , Mäkelä Sanna , Savolainen Markku J. , Hannuksela Minna L. , Jauhiainen Matti , Taskinen Marja‐Riitta , Kaski Kimmo , Ala‐Korpela Mika 
Published: January 2007

Abstract1H NMR spectra of plasma are known to provide specific information on lipoprotein subclasses in the form of complex overlapping resonances. A combination of 1H NMR and self‐organising map (SOM) analysis was applied to investigate if automated characterisation of subclass‐related metabolic interactions can be achieved. To reliably assess the intrinsic capability of 1H NMR for resolving lipoprotein subclass profiles, sum spectra representing the pure lipoprotein subclass part of actual plasma were simulated with the aid of experimentally derived model signals for 11 distinct lipoprotein subclasses. Two biochemically characteristic categories of spectra, representing normolipidaemic and metabolic syndrome status, were generated with corresponding lipoprotein subclass profiles. A set of spectra representing a metabolic pathway between the two categories was also generated. The SOM analysis, based solely on the aliphatic resonances of these simulated spectra, clearly revealed the lipoprotein subclass profiles and their changes. Comparable SOM analysis in a group of 69 experimental 1H NMR spectra of serum samples, which according to biochemical analyses represented a wide range of lipoprotein lipid concentrations, corroborated the findings based on the simulated data. Interestingly, the choline N(CH3)3 region seems to provide more resolved clustering of lipoprotein subclasses in the SOM analyses than the methyl CH3 region commonly used for subclass quantification. The results illustrate the inherent suitability of 1H NMR metabonomics for automated studies of lipoprotein subclass‐related metabolism and demonstrate the power of SOM analysis in an extensive and representative case of 1H NMR metabonomics. Copyright © 2007 John Wiley & Sons, Ltd.
Introducing environmental constraints in generation expansion problems
Authors: Marques Marcato Rachel , Sagastizábal Claudia 
Published: January 2007

AbstractGeneration expansion planning problems should take into account not only satisfaction of future demand but also environmental constraints, such as government imposed limits on pollution produced by coal‐based power plants. For a vertically integrated system of power plants, we model those features as a two‐stage stochastic programming problem with recourse that can be solved by decomposition methods. We present results for different demand scenarios, corresponding to low, medium, and high economic future growth, as well as different environmental cases, with stringent and non‐stringent emission limits for the thermal plants composing the electric mix. Copyright © 2006 John Wiley & Sons, Ltd.
A note on the efficiency of the conjugate gradient method for a class of time‐dependent problems
Authors: Cai Xing , Nielsen Bjørn Fredrik , Tveito Aslak 
Published: January 2007

AbstractWe discuss the efficiency of the conjugate gradient (CG) method for solving a sequence of linear systems; Aun+1 = un, where A is assumed to be sparse, symmetric, and positive definite. We show that under certain conditions the Krylov subspace, which is generated when solving the first linear system Au1 = u0, contains the solutions {un} for subsequent time steps. The solutions of these equations can therefore be computed by a straightforward projection of the right‐hand side onto the already computed Krylov subspace.Our theoretical considerations are illustrated by numerical experiments that compare this method with the order‐optimal scheme obtained by applying the multigrid method as a preconditioner for the CG‐method at each time step. Copyright © 2007 John Wiley & Sons, Ltd.
Properties of vinyl ester resins containing methacrylated fatty acid comonomer: the effect of fatty acid chain length
Authors: Dey Tania 
Published: January 2007

AbstractThis paper reports the formulation of a low‐cost vinyl ester‐based composite resin suitable for liquid molding, which has significantly lower volatile organic compound emission associated with it. Methacrylated fatty acid comonomers were used to replace the conventional yet environmentally hazardous reactive diluent, styrene. The chain length of these fatty acids played a key role in obtaining better viscosity, as it was proved to affect two interplaying factors: intermolecular friction and hydrogen bonding. The thermomechanical performance was greatly affected by the chain length of the fatty acids as well as the crosslink density of the polymer networks. A carbon number of 6 to 8 was good enough in optimizing the viscosity parameter suitable for handling; the dynamic mechanical analysis values, namely glass transition temperature and storage modulus, were in the range 66–121 °C and 0.97–2.8 GPa, respectively, as the carbon number was varied from 4 to 16, making the material suitable for various applications. Microstructures obtained from scanning electron microscopy results were correlated with polymer properties to obtain a better insight into these polymer networks. Copyright © 2007 Society of Chemical Industry
Catalytic reactions of oxetanes with protonic reagents and aprotic reagents leading to novel polymers
Authors: Kudo Hiroto , Nishikubo Tadatomi 
Published: January 2007

AbstractThis paper reports new addition reactions of oxetanes with certain protonic reagents such as carboxylic acid, phenol, and thiol, and with certain aprotic reagents such as acyl chloride, thioester, phosphonyl dichloride, silyl chloride, and chloroformate using quaternary onium salts as catalysts. The kinetic study of the addition reactions of oxetanes was also investigated. These new addition reactions were applicable to the synthesis of new polymers. These polyaddition systems could also construct both polymer main chains and reactive side chains. The alternating copolymerization of oxetanes with carboxylic anhydride was performed. Furthermore, it was found that anionic ring‐opening polymerization of oxetanes containing hydroxy groups proceeded to afford the hyperbranched polymer (HBP) with an oxetanyl group and many hydroxy groups at the ends of the polymer chains. Alkali developable photofunctional HBPs were synthesized by the polyaddition of bis(oxetane)s or tris(oxetane)s, and their patterning properties were examined, too. The photo‐induced cationic polymerization of the polymers with pendant oxetanyl groups and the thermal curing reactions of polyfunctional oxetanes (oxetane resins) were also examined to give the crosslinking materials quantitatively. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 709–726, 2007