bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Vinylanthracene and Vinylferrocene‐Containing Copolymer: A New Dual pH/Sulfide Sensor
Authors: Robinson Kay L. , Lawrence Nathan S. 
Published: March 2006

AbstractA single electroactive copolymer containing both anthracene and ferrocene units has been synthesized to form a dual pH/sulfide sensor. Under cyclic voltammetric conditions the oxidation of the ferrocene moiety undergoes an electrocatalytic reaction with sulfide, producing a linear increase in the oxidative peak current over the range 0.2–2.0 mM. Furthermore, square wave voltammetry was utilized to determine the pH of the solution by measuring the variation in the anthracene oxidation potential with respect to the ferrocene oxidation wave.
Voltammetric Monitoring and Speciation of Copper Ions in Italian “Grappa” with Platinum Microelectrodes
Authors: Baldo M. Antonietta , Daniele Salvatore 
Published: March 2006

AbstractA linear sweep voltammetric (LSV) investigation and the anodic stripping voltammetric (ASV) detection of copper ions in ethanol‐water mixtures and grappa samples are reported. The measurements are carried out by using platinum microdisk electrodes. Ethanol‐water mixtures with ethanol content in the range 40–100 vol%, commercially available and raw grappa samples having ethanol content in the above range are examined. From LSV measurements of copper (II) ions added to the samples, the formation of intermediate copper (I) soluble species, which are stabilized mainly by the naturally occurring organic compounds present in the real samples, is observed. The analysis of LSV and ASV current responses against added Cu2+ ions provides linear trends over the concentration range 5×10−5−5×10−3 M and 5×10−7−5×10−5 M, respectively. The sensitivity depends on the ethanol content in the mixture and, as expected, it is the higher the lower the viscosity of the medium. In particular, it varies from 1.54 to 3.53 nA mM−1 and from 0.114 to 0.263 nA μM−1 for LSV and ASV measurements, respectively, upon changing the ethanol content from 40 to 100 vol%. In the same range of ethanol content, detection limits obtained by ASV vary from 0.27 to 0.15 μM, respectively. Labile or total copper contents in the grappa samples are determined by ASV measurements performed in the untreated matrices or in the samples acidified with 0.1 M HClO4, respectively. Finally, acidification of the samples with different amounts of HClO4 allows also some speciation investigations to be performed.
X‐Ray Photoelectron Spectroscopy and Electron Microscopy of Hydralazinium Ion‐Selective Electrode Membrane's Surface
Authors: Shoukry Adel F. , Maraffie Hayat M. , El‐Shatti Laila A. 
Published: March 2006

AbstractNew hydralazinium (Hz) plastic membrane electrodes of either conventional or coated‐wire type were constructed based on incorporation of Hz‐phosphotungstate (Hz‐PT) ion associate or Hz‐reineckate (Hz‐Rn) ion‐pair in poly(vinyl chloride) membranes. The (Hz‐PT)‐based electrodes required 30 minutes conditioning time to exhibit nearly Nernstian response over the concentration range 1.58×10−5–1.7×10−2 M HzCl. They also showed life span of 17 days, working pH range of 3.2 to 9.4 and high selectivity for Hz towards Na+, K+, Mg2+ and Ca2+. The electrodes have not lost their efficiency at temperatures elevated up to 60 °C. They were successfully employed to assaying HzCl in a pharmaceutical preparation. The electrode containing (Hz‐Rn) ion‐pair required 30 minutes conditioning time to show response for Hz over the concentration range 2.5×10−5–5.6×10−2 M. The life span of the electrode was only 8 h. X‐ray photoelectron spectroscopy was applied to investigate the effect of prolonged soaking on the membrane's surface of both types of electrodes. The surfaces of fresh and expired membranes containing Hz‐PT were also examined by electron microscopy. The results indicated that the limitation of the life span of plastic membrane electrodes is attributed to leaching of the ion exchanger from the membrane to the test solution in addition to deformation at the surface of the expired electrode.
Synthesis, Design and Electrochemical Properties of Langmuir–Blodgett (LB) Films Built of Bis(Pyrrolyl)Fluorene
Authors: Cabaj Joanna , Sołoducho Jadwiga , Nowakowska Anna , Chyla Antoni 
Published: March 2006

AbstractThe synthesis, characterization, electropolymerization, electrical and sensing properties of LB films of mono‐ and dihexadecyl‐bis(pyrrolyl)fluorene derivatives are reported. Different responses to different gases at various concentrations obtained for mono‐ and disubstituted derivatives of bis(pyrrolyl)fluorene make these materials a very good candidates for elements of gas sensing devices of the different type of an “artificial nose” or a neuronic network.
Tailoring Solution Cast Poly(3,4‐dioctyloxythiophene) Transducers for Potentiometric All‐Solid‐State Ion‐Selective Electrodes
Authors: Michalska Agata , Skompska Magdalena , Mieczkowski Józef , Zagórska Małgorzata , Maksymiuk Krzysztof 
Published: March 2006

AbstractA novel concept of tailoring potentiometric responses of all‐solid‐state ion‐selective electrodes was introduced. The effect of composition and resulting properties of the conjugated polymer transducer, placed between the electrode support and ion‐selective membrane, on analytical characteristic of obtained sensors was studied.
An Eulerian approach to fluid–structure interaction and goal‐oriented mesh adaptation
Authors: Dunne Th. 
Published: March 2006

AbstractWe propose an Eulerian framework for modelling fluid–structure interaction (FSI) of incompressible fluids and elastic structures. The model is based on an Eulerian approach for describing structural dynamics. This is achieved by tracking the movement of the initial positions of all ‘material’ points. In this approach the displacement appears as a primary variable in an Eulerian framework.Our approach uses a technique which is similar to the level set method in so far that it also tracks initial data, in our case the set of initial positions (IP), and from this determines to which ‘phase’ a point belongs. To avoid the occasional reinitialization of the initial position set we employ the harmonic continuation of the structure velocity field into the fluid domain.By using the IP set for tracking the structure displacement, we can ensure that corners and edges of the fluid–structure interface are preserved well.Based on this monolythic model of the FSI we apply the Dual Weighted Residual (DWR) method for goal‐oriented a posteriori error estimation to stationary FSI problems.Examples are presented based on the model and for the goal‐oriented local mesh adaptation. Copyright © 2006 John Wiley & Sons, Ltd.
Haplotype analysis in the presence of informatively missing genotype data
Authors: Liu Nianjun , Beerman Isabel , Lifton Richard , Zhao Hongyu 
Published: March 2006

AbstractIt is common to have missing genotypes in practical genetic studies, but the exact underlying missing data mechanism is generally unknown to the investigators. Although some statistical methods can handle missing data, they usually assume that genotypes are missing at random, that is, at a given marker, different genotypes and different alleles are missing with the same probability. These include those methods on haplotype frequency estimation and haplotype association analysis. However, it is likely that this simple assumption does not hold in practice, yet few studies to date have examined the magnitude of the effects when this simplifying assumption is violated. In this study, we demonstrate that the violation of this assumption may lead to serious bias in haplotype frequency estimates, and haplotype association analysis based on this assumption can induce both false‐positive and false‐negative evidence of association. To address this limitation in the current methods, we propose a general missing data model to characterize missing data patterns across a set of two or more markers simultaneously. We prove that haplotype frequencies and missing data probabilities are identifiable if and only if there is linkage disequilibrium between these markers under our general missing data model. Simulation studies on the analysis of haplotypes consisting of two single nucleotide polymorphisms illustrate that our proposed model can reduce the bias both for haplotype frequency estimates and association analysis due to incorrect assumption on the missing data mechanism. Finally, we illustrate the utilities of our method through its application to a real data set. Genet. Epidemiol. 2006. © 2006 Wiley‐Liss, Inc.
Two‐connected orientations of Eulerian graphs
Authors: Berg Alex R. , Jordán Tibor 
Published: March 2006

AbstractA graph G = (V, E) is said to be weakly four‐connected if G is 4‐edge‐connected and G – x is 2‐edge‐connected for every x ∈ V. We prove that every weakly four‐connected Eulerian graph has a 2‐connected Eulerian orientation. This verifies a special case of a conjecture of A. Frank . © 2006 Wiley Periodicals, Inc. J Graph Theory 52: 230–242, 2006
Isomorphic factorization of the complete graph into Cayley digraphs
Authors: Chia G. L. , Ong Poh‐Hwa 
Published: March 2006

AbstractLet Zp denote the cyclic group of order p where p is a prime number. Let X = X(Zp, H) denote the Cayley digraph of Zp with respect to the symbol H. We obtain a necessary and sufficient condition on H so that the complete graph on p vertices can be edge‐partitioned into three copies of Cayley digraphs of the same group Zp each isomorphic to X. Based on this condition on H, we then enumerate all such Cayley graphs and digraphs. © 2006 Wiley Periodicals, Inc. J Graph Theory 52: 243–256, 2006
Rectangular and visibility representations of infinite planar graphs
Authors: Thomassen Carsten 
Published: March 2006

AbstractWe provide a new method for extending results on finite planar graphs to the infinite case. Thus a result of Ungar on finite graphs has the following extension: Every infinite, planar, cubic, cyclically 4‐edge‐connected graph has a representation in the plane such that every edge is a horizontal or vertical straight line segment, and such that no two edges cross. A result of Tamassia and Tollis extends as follows: Every countably infinite planar graph is a subgraph of a visibility graph. Furthermore, every locally finite, 2‐connected, planar graph is a visibility graph. © 2006 Wiley Periodicals, Inc. J Graph Theory 52: 257–265, 2006
Bone marrow stromal cells induce BMP2/4 production in oxygen‐glucose‐deprived astrocytes, which promotes an astrocytic phenotype in adult subventricular progenitor cells
Authors: Xin Hongqi , Li Yi , Chen Xiaoguang , Chopp Michael 
Published: March 2006

AbstractBone morphogenetic proteins (BMPs) affect cell proliferation and differentiation. Astrocytes in ischemic brain are highly responsive to bone marrow stromal cell (BMSC) treatment. We investigated the effects of BMSCs on astrocytes cultured under oxygen‐ and glucose‐deprived conditions, which in part simulate in vivo stroke conditions, to test the hypothesis that BMSCs alter astrocytic expression of BMPs which may contribute to neurological functional recovery of stroke. Quantitative real‐time RT‐PCR showed that the expression of BMP2/4 mRNAs decreased within ischemic astrocytes, In contrast, BMP2/4 mRNA was significantly increased after cocultured with BMSCs. Western blotting also confirmed this increase at the protein level in the medium of ischemic astrocytes after coculture with BMSCs. As a source of neural stem and progenitor cells, cultured subventricular zone (SVZ) neurospheres exposed to medium obtained from ischemic astrocytes cocultured with BMSCs were significantly enriched in cells expressing the astrocytic marker glial fibrillary acidic protein (GFAP), but not at the expense of β‐III‐tubulin‐positive SVZ neuroblasts. The expression of BMP2/4 subsequently increased the phosphorylation of downstream effector Smad1 and the expression of notch signal pathway‐induced protein Hes1 in cultured SVZ neurospheres. BMP antagonist Noggin blocked the elevation of phosphorylated Smad1 and the expression of Hes1 as well as reducing the percentage of astrocytic SVZ progenitor cells. Our results indicate that BMSCs increase BMP2/4 expression in ischemic astrocytes. These changes enhance subventricular progenitor cell gliogenesis by activating relevant signaling pathways. BMSC‐stimulated signaling of endogenous astrocytes may alter the ischemic environment, promoting remodeling of brain and hence, improve functional recovery after stroke. © 2006 Wiley‐Liss, Inc.
A Schrödinger operator with a δ′‐interaction on a Cantor set and Krein–Feller operators
Authors: Albeverio Sergio , Nizhnik Leonid 
Published: March 2006

AbstractA construction of a one‐dimensional Schrödinger operator that has an inner structure defined on a set of Lebesgue measure zero and an interaction given on such a set. General Krein–Feller operators are constructed and the spectrum of a Schrödinger operator with a δ′‐interaction given on a Cantor set is studied. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dehn surgeries on periodic links
Authors: Barbieri E. , Cavicchioli A. , Spaggiari F. 
Published: March 2006

AbstractWe consider orientable closed connected 3‐manifolds obtained by Dehn surgeries with rational coefficients along the components of certain periodic links. These manifolds extend many classes of (hyperbolic) manifolds considered by several authors (see the references). We find geometric presentations of the fundamental group of such manifolds, and study some covering properties of them. Then we obtain results on their geometric structures in many cases. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mod 2 degree and a generalized No Retraction Theorem
Authors: Bloch Ethan D. 
Published: March 2006

AbstractWe provide elementary proofs of generalized versions of the No Retraction Theorem and Sperner's Lemma, and a simple definition of mod 2 degree of certain maps. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Rank one perturbations of Jacobi matrices with mixed spectra
Authors: del Rio R. , Kudryavtsev M. , Silva L. 
Published: March 2006

AbstractLet A be a self‐adjoint operator and φ its cyclic vector. In this work we study spectral properties of rank one perturbations of A
Aθ = A + θ 〈φ , ·〉φ
in relation to their dependence on the real parameter θ . We find bounds on averages of spectral measures for semi‐infinite Jacobi matrices and give criteria which guarantee existence of mixed spectral types for θ in a set of positive Lebesgue measure. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Orthogonal rational matrix‐valued functions on the unit circle: Recurrence relations and a Favard‐type theorem
Authors: Fritzsche Bernd , Kirstein Bernd , Lasarow Andreas 
Published: March 2006

AbstractThis paper contains further steps towards a Szegö theory for orthogonal rational matrix‐valued functions on the unit circle 𝕋. It continues the investigations started in [18]–[20]. Hereby we are guided by former work of Bultheel, González–Vera, Hendriksen, and Njåstad on scalar orthogonal rational functions on the one side and by research of Delsarte, Genin, and Kamp on matrix polynomials on the other side. In this paper we derive recursion formulas for Christoffel–Darboux pairs of rational matrix functions which lead us to jqq ‐recursively connected pairs of rational matrix functions. Moreover, we prove a Favard‐type theorem for rational matrix functions. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Generalized fractal dimensions on the negative axis for compactly supported measures
Authors: Germinet François , Tcheremchantsev Serguei 
Published: March 2006

AbstractWe study generalized fractal dimensions of measures, called the Hentschel–Procaccia dimensions and the generalized Rényi dimensions. We consider compactly supported Borel measures with finite total mass on a complete separable metric space. More precisely we discuss in great generality finiteness and equality of the different lower and upper dimensions for negative values of their argument q . In particular we do not assume that the measure satisfies to the so called “doubling condition”. A key tool in our analysis is, given a measure μ , the function g (ε ), ε > 0, defined as the infimum over all points x in the support of μ of the quantity μ (B (x , ε )), where B (x , ε ) is the ball centered at x and of radius ε . We provide counter examples to show the optimality of some criteria for finiteness and equality of the dimensions. We also relate this work to quantum dynamics. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characterizations of stable laws via functional equations
Authors: Gupta Arjun K. , Jagannathan Keshav , Nguyen Truc T. , Shanbhag Damodar N. 
Published: March 2006

AbstractIn this paper, characterizations of continuous and discrete stable laws are given using Deny's Theorem. These results are obtained using infinite divisibility property of the characteristic function, and the ensueing functional equations are solved using either Deny's Theorem or the Lau–Rao Theorem. Multivariate versions of these results are also given in addition to a multidimensional generalization of the main result. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Singular integrals on Besov spaces
Authors: Hytönen Tuomas , Weis Lutz 
Published: March 2006

AbstractThe boundedness of singular convolution operators f ↦ k ∗︁ f is studied on Besov spaces of vector‐valued functions, the kernel k taking values in ℒ︁(X , Y ). The main result is a Hörmander‐type theorem giving sufficient conditions for the boundedness of such an operator on these spaces. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Boundedness of solutions for a class of reversible systems
Authors: Yang Xiaojing 
Published: March 2006

AbstractIn this paper, we are concerned with the problem of boundedness of solutions for the second order differential equation x ″ + f (x )x ′ + g (x ) = e (t ), where f , g ∈ C ∞(ℝ) are odd functions and e (t ) ∈ C ∞(ℝ/ℤ) is odd. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On finite elements in vector lattices and Banach lattices
Authors: Chen Z. L. , Weber M. R. 
Published: March 2006

AbstractIn Archimedean vector lattices we show that each element of the band generated by a finite element is also finite. In vector lattices with the (PPP) and in Banach lattices we obtain some characterizations of finite elements by using the generalized order units for principal bands. In the case of Banach lattices with order continuous norm the ideal of all finite elements coincides with the linear span of all atoms. Some other related results and applications are included. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Operator holes and extensions of sectorial operators and dual pairs of contractions
Authors: Malamud Mark 
Published: March 2006

AbstractWe find a criterion of existence and uniqueness of an m ‐sectorial extension of a dual pair {A 1, A 2} of nonnegative operators. A description of the set of all such extensions of a dual pair {A 1, A 2} is obtained too. A complete description of the set of all proper and improper m ‐sectorial extensions of a nonnegative operator is also obtained. All the problems are reduced to similar problems for a dual pair {T 1, T 2} of non‐densely defined symmetric contractions Tj = (I – Aj )(I + Aj )–1, j ∈ {1, 2}. In turn these problems are reduced to the investigation of the corresponding operator “holes”, intersections of two operator balls. Basically, complexity of the problem depends upon that whether the left/right radii of the operator ball(s) coincide or not. A parametrization of an operator hole with equal left and right radii is obtained. Solutions to the above problems are based on such a parametrization.Some classes of non‐contractive extensions of the dual pair {T 1, T 2} are described too. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Gas‐phase ion chemistry in organometallic systems
Authors: Operti Lorenza , Rabezzana Roberto 
Published: March 2006

AbstractThis review essentially deals with positive ion/molecule reactions occurring in gas‐phase organometallic systems, and encompasses a period of time of approximately 7 years, going from 1997 to early 2004. Following the example of the excellent review by Eller & Schwarz (1991; Chem Rev 91:1121–1177), in the first part, results of reaction of naked ions are presented by grouping them according to the neutral substrate, while in the second part, ligated ions are grouped according to the different ligands. Whenever possible, comparison among similar studies is attempted, and general trends of reactivities are evidenced. © 2005 Wiley Periodicals, Inc., Mass Spec Rev 25:483–513, 2006
Multicontrast sequences with continuous table motion: A novel acquisition technique for extended field of view imaging
Authors: Sommer Gregor , Fautz Hans‐Peter , Ludwig Ute , Hennig Jürgen 
Published: March 2006

AbstractA novel acquisition technique called multicontrast imaging is presented that provides multiple datasets of different image contrasts covering an extended field of view within one measurement procedure. The technique uses a continuously moving table and is based on the repetitive acquisition of axial volume sections while the patient moves through the scanner once. To compensate for the table motion during the measurement, adaptive slice shifting is applied. Multicontrast imaging is designed to combine the comfort of a moving table examination with the high time efficiency of a multitask protocol and can be used for generating differences in both contrast and spatial parameters of the acquired data. The technique and its properties are demonstrated on healthy human volunteers. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Robust quantification of short echo time 1H magnetic resonance spectra using the Padé approximant
Authors: Williamson David C. , Hawesa Halima , Thacker Neil A. , Williams Stephen R. 
Published: March 2006

AbstractAccurate quantification of in vivo short echo time spectra is hampered by the presence of overlapping peaks and a significant baseline. In this work the Padé approximant in conjunction with Monte Carlo simulation is used to extract peak areas from short echo time 1H spectra. We exploit the fact that the Padé approximant is known to model broad non‐Lorentzian signals as arbitrary sums of Lorentzian components to separate baseline components from sharper metabolite signals by combining the Padé approximant with Monte Carlo simulation. The simulation results demonstrate that the Padé approximant–Monte Carlo hybrid analysis is able to separate the metabolite signals from the baseline, while a least squares fitting of a time domain model may result in significant bias of the peak area estimations. For the in vivo data the estimates of the peak areas using the Padé approximant and AMARES compare well, with the exception of the NAA peak at 2.02 ppm. We suggest that the discrepancy may be due to the baseline contamination as supported by the simulation results; however, without an in vivo gold standard this remains difficult to demonstrate. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.