bluuebunny/crossref_metadata_2025_split huggingface dataset:
Horseshoe crab sperm contain a unique isoform of arginine kinase that is present in midpiece and flagellum
Authors: Strong S. J. , Ellington W. R. 
Published: September 2005

AbstractSpermatozoa of the horseshoe crab, Limulus polyphemus, contained high activities of arginine kinase (AK), the bulk of which was completely solubilized in buffer lacking detergent. Sperm AK, along with the fast isoform of muscle AK, were purified to homogeneity. Sperm AK had similar electrophoretic mobility on cellulose acetate to that of muscle AK. In contrast, sperm AK ran somewhat slower than muscle AK on SDS‐PAGE, indicating that this protein has a higher relative molecular mass (44 kD vs. 41 kD). These two forms also showed different chromatographic behavior on a reverse‐phase HPLC column. Peptide maps of cyanogen bromide cleavage fragments of sperm and muscle AK showed distinct differences. Collectively, these data suggest that the sperm of L. polyphemus contain a unique AK isoform. Polyclonal anti‐muscle AK antibodies, which showed strong reactivity against sperm AK, were used to localize AK in sperm. Both indirect immunofluorescence and immunogold transmission electron microscopy showed that AK was present in the midpiece in the vicinity of the mitochondria and also along the length of the flagellum. Given the polarized geometry of these cells, it appears that the AK reaction may play a role in high energy phosphate transport to dynein ATPases in the flagellum. © 1993 Wiley‐Liss, Inc.
Different distribution of epidermal basal cells in the anuran larval skin correlates with the skin's region‐specific fate at metamorphosis
Authors: Izutsu Yumi , Kaiho Masayoshi , Yoshizato Katsutoshi 
Published: September 2005

AbstractThe epidermis of the body skin in anurans undergoes a metamorphic fate different from that of the tail skin. The former survives metamorphosis and is transformed into the adult type, while the latter is subject to apoptosis. In a search for an explanation for this regional specificity at the cellular level, the epidermis of tadpoles of the bullfrog, Rana catesbeiana, was characterized histologically and immunohistochemically during metamorphosis and was compared between the body and the tail. No histological difference in the epidermis was apparent between the two tissues at stages I and II defined by Taylor and Kollros (Anatomical Record94:7–23, 1946). A clear difference was first noticed at late stage III with respect to basal cells, which are thought to be the progenitor cells of the germinative basal cells of the adult‐type epidermis: basal cells appeared at this stage in the body but not in the tail. At stage X, about 22% of epidermal cells were basal cells in the body, whereas there were still no basal cells in the tail. However, we present histological evidence for the presence of adult‐type cells in the tail at the late stages of climax. Weak but consistent expression of adult antigens in the tail skin was also demonstrated immunohistochemically with antibodies against human blood group A antigen, which cross‐react with an epitope present in adult‐type epidermal cells. We conclude that even the tail epidermis, a larva‐specific tissue, contains a population of cells that can differentiate into adult‐type cells. The different distribution of basal cells between the body and the tail epidermis closely correlates with the difference in metamorphic fate between the two tissues. © 1993 Wiley‐Liss, Inc.
In vitro spontaneous cytotoxic activity against mammalian target cells by the hemocytes of the solitary ascidian, Ciona intestinalis
Authors: Peddie Clare M. , Smith Valerie J. 
Published: September 2005

AbstractBlood cell‐mediated cytotoxic activity against mammalian target cells by the hemocytes of the solitary ascidian Ciona intestinalis was investigated in vitro by fluorochromasia. Salt‐conditioned target cells were labeled with carboxyfluorescein diacetate and challenged with mixed and separated hemocytes. The assay provided optimal conditions for the functioning of the effector hemocytes while maintaining low background leakage from the target cells. Comparison of different hemocyte populations, separated by density gradient centrifugation, revealed that only cell bands containing the phagocytic and nonphagocytic amoebocytes exhibited cytotoxicity. Experiments to characterize cytolysis demonstrated that activity increased with the effector to target cell ratio, occurred within 15 min, and was maximal at an incubation temperature of 20°C. Both human (K562) and mouse [YAC‐1, P815, WEHI (3B) and L929] target cell lines were killed by the ascidian effector hemocytes. This paper demonstrates a population of nonspecific cytotoxic effector cells in the blood of C. intestinalis that are able to spontaneously kill a range of mammalian targets in vitro. © 1993 Wiley‐Liss, Inc.
Deficiency indices and spectral theory of third order differential operators on the half line
Authors: Behncke Horst , Hinton Don 
Published: September 2005

AbstractWe investigate the spectral theory of a general third order formally symmetric differential expression of the form

acting in the Hilbert space ℒ︁2w (a ,∞). A Kummer–Liouville transformation is introduced which produces a differential operator unitarily equivalent to L . By means of the Kummer–Liouville transformation and asymptotic integration, the asymptotic solutions of L [y ] = zy are found. From the asymptotic integration, the deficiency indices are found for the minimal operator associated with L . For a class of operators with deficiency index (2, 2), it is further proved that almost all selfadjoint extensions of the minimal operator have a discrete spectrum which is necessarily unbounded below. There are however also operators with continuous spectrum. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Sturm–Liouville problems with singular non‐selfadjoint boundary conditions
Authors: Eberhard Walter , Freiling Gerhard , Zettl Anton 
Published: September 2005

AbstractSingular boundary conditions are formulated for non‐selfadjoint Sturm–Liouville problems which are limitcircle in a very general sense. The characteristic determinant is constructed and it is shown that it can be used to extend the Birkhoff theory for so called “Birkhoff regular boundary conditions” to the singular case. This is illustrated for a class of singular Birkhoff‐regular problems; in particular we prove for this class an asymptotic formula for the eigenvalues and an expansion theorem. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A glimpse into the life and times of F. V. Atkinson
Authors: Mingarelli Angelo B. 
Published: September 2005

AbstractWe review the life and scientific work of F. V. Atkinson, mathematician. The article consists of a brief overview of his academic and professional life followed by an extensive compilation of his life's work, some unpublished. He is best remembered for his contributions to Number Theory (mean value theorems for the Riemann zetafunction on the critical line), his work in operator theory (index theorems for abstract Fredholm operators), and his seminal work in many areas of differential equations (multiparameter spectral theory, Sturm–Liouville theory, asymptotics, etc.). (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Best Sobolev constants and quasi‐linear elliptic equations with critical growth on spheres
Authors: Bandle C. , Peletier L. A. , Stingelin S. 
Published: September 2005

AbstractSharp existence and nonexistence results for positive solutions of quasilinear elliptic equations with critical growth in geodesic balls on spheres are established. The arguments are based on Pohozaev type identities and asymptotic estimates for Emden–Fowler type equations. By means of spherical symmetrization and the concentration‐compactness principle existence and nonexistence results for general domains on spheres are obtained. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Counting eigenvalues of biharmonic operators with magnetic fields
Authors: Evans W. D. , Lewis R. T. 
Published: September 2005

AbstractAn analysis is given of the spectral properties of perturbations of the magnetic bi‐harmonic operator Δ2A in L 2(Rn ), n = 2, 3, 4, where A is a magnetic vector potential of Aharonov–Bohm type, and bounds for the number of negative eigenvalues are established. Key elements of the proofs are newly derived Rellich inequalities for Δ2A which are shown to have a bearing on the limiting cases of embedding theorems for Sobolev spaces H 2(Rn ). (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Additional spectral properties of the fourth‐order Bessel‐type differential equation
Authors: Everitt W. N. , Kalf H. , Littlejohn L. L. , Markett C. 
Published: September 2005

AbstractThis paper discusses the spectral properties of the self‐adjoint differential operator generated by the fourth‐order Bessel‐type differential expression, as defined by Everitt and Markett in 1994, in a Lebesgue–Stieltjes Hilbert function space. This space involves functions defined on the real line; the Lebesgue–Stieltjes measure is locally absolutely continuous on the real line, with the origin removed; the origin itself has strictly positive measure. It is shown that there is a unique such self‐adjoint operator; this operator has no eigenvalues but has a continuous spectrum on the positive half‐line of the spectral plane. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A non‐standard multiparameter eigenvalue problem in ordinary differential equations
Authors: Faierman M. , Mennicken R. 
Published: September 2005

AbstractWe consider two simultaneous Sturm–Liouville systems involving three spectral parameters. However unlike the standard multiparameter problem, we now suppose that the principal part of each of the differential operators involved is multiplied by a different parameter. For such a non‐standard system we establish the oscillation theory and discuss the associated eigenfunction expansion. Some open problems concerning the eigenfunction expansion are also presented. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Inverse problems for differential operators with singular boundary conditions
Authors: Freiling Gerhard , Yurko Vjacheslav 
Published: September 2005

AbstractSingular boundary conditions are formulated for Sturm–Liouville operators having singularities and turning points at the end‐points of the interval. For boundary‐value problems with singular boundary conditions, inverse problems of spectral analysis are studied. We give formulations of the inverse problems both for the case of separated and non‐separated singular boundary conditions. For each class of inverse problems we prove a uniqueness theorem and give a procedure for constructing the solution of the inverse problem. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Limits of zeros of orthogonal polynomials on the circle
Authors: Simon Barry , Totik Vilmos 
Published: September 2005

AbstractWe prove that there is a universal measure on the unit circle such that any probability measure on the unit disk is the limit distribution of some subsequence of the corresponding orthogonal polynomials. This follows from an extension of a result of Alfaro and Vigil (which answered a question of P. Turán): namely, for n < N , one can freely prescribe the n ‐th polynomial and N – n zeros of the N ‐th one. We shall also describe all possible limit sets of zeros within the unit disk. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Two perspectives on reduction of ordinary differential equations
Authors: Zagaris Antonios , Kaper Hans G. , Kaper Tasso J. 
Published: September 2005

AbstractThis article is concerned with general nonlinear evolution equations x ′ = g (x ) in RN involving multiple time scales, where fast dynamics take the orbits close to an invariant low‐dimensional manifold and slow dynamics take over as the state approaches the manifold. Reduction techniques offer a systematic way to identify the slow manifold and reduce the original equation to an autonomous equation on the slow manifold. The focus in this article is on two particular reduction techniques, namely, computational singular perturbation (CSP) proposed by Lam and Goussis [Twenty‐Second Symposium (International) on Combustion, The University of Washington, Seattle, Washington, August 14–19, 1988 (The Combustion Institute, Pittsburgh, 1988), pp. 931–941] and the zero‐derivative principle (ZDP) proposed recently by Gear and Kevrekidis [Constraint‐defined manifolds: A legacy‐code approach to low‐dimensional computation, SIAM J. Sci. Comput., to appear]. It is shown that the tangent bundle to the state space offers a unifying framework for CSP and ZDP. Both techniques generate coordinate systems in the tangent bundle that are natural for the approximation of the slow manifold. Viewed from this more general perspective, both CSP and ZDP generate, at each iteration, approximate normal forms for the system under examination. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Friedrichs extension and essential spectrum of systems of differential operators of mixed order
Authors: Kusche Tobias , Mennicken Reinhard , Möller Manfred 
Published: September 2005

AbstractA general construction for the Friedrichs extension of symmetric semi‐bounded block operators

with not necessarily bounded entries, acting in the product of Hilbert spaces has been given by Konstantinov and Mennicken via the form

There the entry A was assumed to be essentially self‐adjoint. Here it will be shown that the result remains true if A is only symmetric and that the closability of γμ follows from the semiboundedness of L 0. This will be applied to a 2 × 2 system of singular mixed‐order differential equations satisfying the quasi‐regularity condition, thus enabling us to give a much simpler calculation for the essential spectrum than in papers by Hardt, Mennicken, Naboko and Faierman, Mennicken, Möller, respectively, for a related 3 × 3‐system. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Proton Conducting Polysulfone Ionomers Carrying Sulfoaryloxybenzoyl Side Chains
Authors: Lafitte Benoît , Puchner Mario , Jannasch Patric 
Published: September 2005

AbstractSummary: Novel proton conducting ionomers have been prepared by attaching pendant sulfonated aromatic side chains to polysulfone. Lithiated polysulfone was first reacted with 4‐fluorobenzoic acid chloride to introduce 4‐fluorobenzoyl side chains to the polymer main chain. Next, the activated fluoro groups were replaced by 4‐sulfophenoxy or 7‐sulfo‐2‐naphthoxy in a potassium carbonate‐mediated nucleophilic substitution reaction. This reaction proceeded under full conversion and the degree of substitution was easily controlled by the degree of lithiation in the first step. Membranes based on ionomers carrying one sulfophenoxybenzoyl unit per polymer repeat unit reached a proton conductivity exceeding 30 mS · cm−1 at 120 °C under immersed conditions.Structures of sulfophenoxybenzoyl polysulfone and sulfonaphthoxybenzoyl polysulfone.magnified imageStructures of sulfophenoxybenzoyl polysulfone and sulfonaphthoxybenzoyl polysulfone.
Thermal Properties of Aromatic Polycarbonates Copolymers Based on Bisphenol A and Tetramethyl Bisphenol A
Authors: Penco Maurizio , Sartore Luciana , Della Sciucca Stefania , Di Ladro Luca , Grassia Luigi , D'Amore Alberto 
Published: September 2005

AbstractStatistical copolycarbonates containing different bisphenol A/tetramethyl bisphenol A (BPA/TMBPA) molar ratios were synthesized by polycondensation reaction between a mixture of the two bisphenols and phosgene. The reaction conditions were selected for producing polymers having comparable molecular weights (M̄n≈9000 g/mol) but different composition, and the same composition but different molecular weights.The calorimetric properties of the products were investigated by differential scanning calorimetry (DSC) and dynamical‐mechanical thermal analysis (DMTA). In particular, the effect of the copolymers molecular characteristics on the glass transition temperature (Tg) and the related relaxation processes were studied.DMTA was employed for evaluating the effect of macromolecular structure on the γ low temperature relaxation peak.
Single Drop Dynamics under Shearing Flow in Systems with a Viscoelastic Phase
Authors: Sibillo Vincenzo , Guido Stefano , Greco Francesco , Maffettone Pier Luca 
Published: September 2005

AbstractIn this article, we discuss the dynamics of a single drop immersed in an immiscible liquid, under an imposed shear flow. The two situations of a viscoelastic matrix with a Newtonian drop and of a viscoelastic drop in a Newtonian matrix are considered, both systems being characterized by a viscosity ratio equal to one, and by the same elasticity parameter. Experimental data are taken with a rheo‐optical computer‐assisted shearing device, allowing for drop observation from the vorticity direction of the shear flow. Data favourably compare with predictions of the recently proposed Maffettone‐Greco model, where the drop is described as a deforming ellipsoid.
Time Scales in Polymer Modified Asphalts
Authors: Polacco Giovanni , Stastna Jiri , Biondi Dario , Vlachovicova Zora , Zanzotto Ludovit , Magagnini Pierluigi 
Published: September 2005

AbstractHistorically, Maxwell was probably the first one who recognized the importance of time scales for understanding the mechanical response of asphalt. In instantaneous response asphalt behaves as an elastic, solid‐like material, on the other hand its long time response is that of a viscous, fluid‐like material. In the linear viscoelastic region asphalt behaves as a low molecular weight polymer. However, in the nonlinear region of high strains or rates of strain the behavior of some asphaltic systems can be rather complicated. In asphalts, asphaltenes, resins and alkanes compose a complex colloidal system, in which alkanes act as a solvent, asphaltenes as micelles and the polar resins as stabilizers. In order to enhance the mechanical properties of asphalts they are frequently modified by blending them with appropriate polymers. Changes in the impermanent network that can be formed in some of these blends can lead to an unexpected behavior of the steady shear viscosity function. Several different time scales emerge from this behavior. A possible relation of these “nonlinear” time scales to the linear viscoelastic time scales is discussed and examples of anomalous behavior of polymer‐modified asphalts are given.
Dielectric and Viscoelastic Study of Entanglement Dynamics: A Review of Recent Findings
Authors: Watanabe Hiroshi , Matsumiya Yumi , Inoue Tadashi 
Published: September 2005

AbstractThis article gives a review of the results of recent dielectric and viscoelastic studies for entangled binary blends of linear cis‐polyisoprenes to explain the current understanding of the equilibrium entanglement dynamics on the basis of the molecular picture of dynamic tube dilation (DTD). Comparison of dielectric and viscoelastic properties reveals that the full‐DTD picture regarding the relaxed portions of the chains as a solvent fails for the high molecular weight component chain in the blends at intermediate times. This failure is related to insufficient constraint release (CR) equilibration of the entanglement segments of this chain. A partial‐DTD picture properly considering this CR equilibration successfully describes the linear relaxation behavior of the blends. The dielectric and viscoelastic properties of PI under fast flow, being affected by the flow‐activated CR/DTD mechanism, are also presented in order to demonstrate the usefulness of the comparison of these properties in both equilibrium and non‐equilibrium states.
Rheology of a Semi‐Rigid Thermotropic Liquid Crystalline Polymer
Authors: Somma E. , Nobile M.R. 
Published: September 2005

AbstractIn this work the rheological behaviour of different Mw samples of a thermotropic liquid crystalline polymer (TLCP), the random copolymer HBA/HNA 73/27 produced by Ticona, has been investigated. The linear viscoelastic behavior has been discussed. The G′ (shear storage modulus) and G″ (shear loss modulus) have been monitored as a function of frequency and of different annealing times. Rheological data obtained in steady state conditions have been used to define the viscosity flow curves for the different MW samples. In all the cases a three regions flow curve has been detected, with the plateau zone being Mw dependent.
Fullerene‐Like Structures as Interaction Sites between Carbon Black and Rubber
Authors: Cataldo Franco 
Published: September 2005

AbstractBall‐milling of N660 carbon black and graphite causes a deep activation of its surface activity which can be measured by a significant increase in the bound rubber level and in the amount of grafted rubber in comparison to the pristine untreated samples.The bound rubber measurement has been done also on a natural rubber masterbatch filled with extracted fullerene carbon black (EFCB). Also in this case extremely high levels of rubber grafting have been achieved in comparison to pure untreated graphite. It is discussed and demonstrated that the fullerene‐like nanostructures in carbon blacks play a key role in the formation of bound rubber phenomenon and in grafting natural rubber on carbon black surface.
Effect of Clay/Diamond and Clay/Carbon Nanosystems on Structure‐Properties Relationships of iPP
Authors: Silvestre Clara , Cimmino Sossio , Raimo Maria , Carfagna Cosimo , Capuano Vincenzo , Kotsilkova Rumiana 
Published: September 2005

AbstractThe effect of the addition of two combined fillers, smectite clay and diamond and smectite clay and carbon nanoparticles, on structure, morphology, isothermal and non isothermal crystallization behaviour, tensile and thermal properties of isotactic polypropylene (iPP) has been investigated by using several techniques: wide angle X‐ray diffraction, optical and scanning electron microscopy, thermogravimetry, differential scanning calorimetry and tensile techniques. It was found that nanoparticles of diamond and carbon favour the nucleation of the β‐form of iPP crystal, whereas the clay nanolayers do not have any influence on the crystal structure of iPP. The thermal stability of iPP/(clay+diamond) and iPP/(clay+carbon) is improved with respect to neat iPP, whereas no influence is detected when only clay is added to iPP. At the given crystallization conditions, the overall crystallization peak of iPP/(clay+diamond) almost exactly overlaps the crystallization peak of neat iPP, whereas in the case of iPP/clay and iPP/(clay+carbon) the maximum of the crystallization peaks is shifted to higher temperature. The spherulite growth rate, G values do not differ from one another. The iPP/(clay+carbon) system shows ductile behavior. The other systems show brittle behavior with failure before necking. These results were related with the very high percentage of beta phase present in the samples of iPP/(clay+carbon).