bluuebunny/crossref_metadata_2025_split huggingface dataset:
Conformations of Highly Charged Dendronized Polymers in Aqueous Solutions of Varying Ionic Strength
Authors: Girbasova Nina , Aseyev Vladimir , Saratovsky Sergey , Moukhina Irina , Tenhu Heikki , Bilibin Alexander 
Published: December 2003

AbstractConformations of two linear, charged dendronized polymers in aqueous solutions of different ionic strengths have been studied by light scattering. Both polymers have a polyacrylic core. The repeating unit of the first of the polymers studied contains a residue of aspartic acid bound to a carboxylic group of the core by an amide group as a first‐generation dendron, whereas the second polymer contains second‐generation dendrons constructed of three molecules of aspartic acid. The dendritic polymers adopt different conformations depending on the generation. Polymers with first‐generation dendrons are flexible and their conformation is sensitive to salt. The polymers with dendrons of the second generation adopt a semi‐flexible rod conformation. Their conformation is not sensitive to salt but is determined by the bulkiness of the dendrons.Polyacrylic polymers having a residue of aspartic acid as a first‐generation dendron (P1), and having a second‐generation dendron on the basis of aspartic acid (P2).magnified imagePolyacrylic polymers having a residue of aspartic acid as a first‐generation dendron (P1), and having a second‐generation dendron on the basis of aspartic acid (P2).
Preparation of Positively and Negatively Charged Organic Colloids from a Single Precursor
Authors: Röder Thorsten , Kramer Thomas , Huber Klaus , Kitzerow Heinz‐S. 
Published: December 2003

AbstractA synthetic route is presented for the preparation of electrically charged colloidal particles with either sign from the same precursor. In the first step, methyl methacrylate was copolymerized with ω‐bromoalkyl acrylate and a cross‐linker, leading to monodisperse, bromo‐functionalized colloids. Substitution of the bromo‐functions by either trimethylamine or Na2SO3 transformed the neutral precursors into positively or negatively charged particles, respectively. The charge density could be varied in two ways: (i) by varying the fraction of bromo‐functionalized monomers; (ii) by increasing the degree of substitution of the bromo‐functions. Derivation of the charged particles from the same precursor colloid made it easier to explain various interesting physical properties of the charged colloidal particles. Higher charge densities were achieved for the cationic colloids. If a threshold value for the charge density of 55 μC · cm−2 was surpassed, the particles showed a significant swelling in aqueous solution.
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Intra‐Molecular Energy Transfer Characteristics of Novel Oligo(thienylphenyl)amine Derivatives Having a Gradient Structure
Authors: Cho Jun‐Sang , Kojima Yojiro , Norifusa Sato , Higuchi Masayoshi , Yamamoto Kimihisa 
Published: December 2003

AbstractOligo(thienylphenyl)amine (TTPA) derivatives which have different thiophene units and potential gradient molecules were synthesized. From the investigation of steady‐state absorption and emission properties and the estimation of the free energy and the energy level of the oligomers, the energy transfer efficiency of the oligomers increased with increasing thiophene units, implying that the energy transfer mainly occurs through space due to a large area overlap existing between the absorption and the emission spectra of the oligomers. Furthermore, based on the calculated Rehm‐Weller equation (ΔGen and ΔGel) and energy diagrams of the oligomers, we found that 4TTPA (4), having a 4‐unit thiophene in the backbone, showed higher energy transfer efficiency compared to that of the others.Molecular structures of TTPA oligomers.magnified imageMolecular structures of TTPA oligomers.
Ternary Gels of a Polymer Blend and a Recycled Oil: Their Use as Bitumen Modifiers
Authors: Barral Marisol , Santamaría Anton , Peña Juan Jose , Eugenia Muñoz M. 
Published: December 2003

AbstractA blend of random ethylene‐vinyl acetate copolymer (EVA) and triblock styrene‐butadiene‐styrene copolymer (SBS) was dissolved in a recycled engine oil to obtain ternary thermoreversible gels. As the temperature was increased, first a network associated with EVA disappeared, and a second one associated with SBS dominated, maintaining the elastic response of the system. The principal advantage of these ternary systems is that their mechanical properties and thermal stability are better than that of binary gels. These gels, made from waste, can be used as bitumen modifiers to obtain binders of improved properties and good stability, which are useful for road surfacing.Temperature sweeps of elastic modulus performed at a frequency of 1 Hz.magnified imageTemperature sweeps of elastic modulus performed at a frequency of 1 Hz.
Objective Evaluation of the Efficiency of Cellulase Finishing of Cotton Fabrics Dyed with Reactive Dyes
Authors: Betcheva Rossitza , Stamenova Maria , Boutris Costas , Tzanov Tzanko 
Published: December 2003

AbstractThis work evaluates the effect of cellulase finishing of dyed cotton fabrics. Fabric samples were dyed with reactive dyes possessing different reactive groups with or without metal atoms in their structures. Enzymatic treatments were carried out with total crude cellulase (TC), purified endoglugonase (EG) and cellobiohydrolase (CBH). The Kawabata system (KES) was used to evaluate the effect of enzymatic treatments depending on the pre‐existing dyes on the cotton fabric. Dyed samples differed significantly from the undyed samples in their physico‐mechanical characteristics after the cellulase application. It was found that the geometrical roughness of fabrics could provide a quantitative description of the influence of the reactive dye structure on the cellulase finishing efficiency.Influence of reactive type group on the relative change of geometrical roughness of dyed fabrics.magnified imageInfluence of reactive type group on the relative change of geometrical roughness of dyed fabrics.
Disentangled State in Polymer Melts; a Route to Ultimate Physical and Mechanical Properties
Authors: Rastogi Sanjay , Kurelec Lada , Cuijpers Juul , Lippits Dirk , Wimmer Markus , Lemstra Piet J. 
Published: December 2003

AbstractThe role of entanglements in obtaining a homogeneous product of ultra high molecular weight polyethylene (UHMW‐PE) has been explored. Studies performed in this report show that a disentangled state before melting is a prerequisite to obtain homogeneous products of an intractable polymer like UHMW‐PE. The disentangled state is obtained directly from the reactor by controlling the polymerisation conditions or in the solid state when there is enhanced chain mobility along the c‐axis of a unit cell. The disentangled state is maintained in the melt over a period of time, invoking implications in polymer rheology. This approach is applicable to polymers in general. The homogeneous fully sintered UHMW‐PE, obtained for the first time, shows a considerable decrease in oxygen permeability, and increase in toughness and fatigue resistance. Such homogeneous products of UHMW‐PE are of beneficial in highly demanding applications, especially in knee‐prosthesis, where the polymer is used as an inlay between the human bone and a metal or ceramic part, which slides against the polyethylene component during normal gait.Phase diagram for the extended chain crystals.magnified imagePhase diagram for the extended chain crystals.
Effect of Copolymer Composition on the Dynamic Mechanical and Thermal Behaviour of Butyl Acrylate‐Acrylonitrile Copolymers
Authors: Suresh Kattimuttathu I. , Sitaramam Bhamidipalli S. , Raju Kothapally V. S. N. 
Published: December 2003

AbstractThis article reports data on the dynamic mechanical and thermal behaviour of butyl acrylate‐acrylonitrile copolymers and their variation with copolymer composition. The copolymers were prepared by emulsion polymerisation techniques, using potassium peroxodisulfate initiator at 80 ± 2 °C. Films were prepared from the latex by casting and analysed by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA) and thermogravimetric analysis (TGA). For copolymer with 0.7 weight fraction of butyl acrylate the dynamic mechanical behaviour was identical to the synthetic rubber NBR (acrylonitrile‐butadiene rubber), such that the storage modulus shows a rapid decay with increasing temperature. The damping characteristics, as indicated by the tan δ value, increased as the weight fraction of butyl acrylate in the copolymer increased. The dynamic mechanical data has been analysed with the WLF‐Equation to study the time‐temperature relationship. The dynamic mechanical properties and glass transition data point to the formation of a copolymer, whose properties vary with acrylonitrile content. Thermogravimetric analysis revealed that weight loss occurring at a particular temperature decreases, along with the decomposition rate, with increase in acrylonitrile content. The activation energy (Ea) for the decomposition was calculated using the Coats & Redfern equation. When temperatures for 10% copolymer decomposition are compared from TGA data, the acrylonitrile rich copolymer starts decomposing at a lower temperature, but the rate of decomposition is slower and yields higher char yields.Effect of copolymer composition on the variation of tan δ (max) at a measuring frequency of 1 Hz.magnified imageEffect of copolymer composition on the variation of tan δ (max) at a measuring frequency of 1 Hz.
Generalized approximation spaces and applications
Authors: Almira Jose Maria , Luther Uwe 
Published: December 2003

AbstractIn the paper we generalize the theory of classical approximation spaces to a much wider class of spaces which are defined with the help of best approximation errors. We also give some applications. For example, we show that generalized approximation spaces can be used to find natural (in some sense) domains of definition of unbounded operators. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Asymptotic completeness for functions of the Laplacian perturbed by potentials and obstacles
Authors: Giere Eckhard 
Published: December 2003

AbstractIn this paper we show with scattering theoretical methods the absence of the singular continuous spectrum for operators that are perturbations of functions of the Laplacian. We extend the semigroup criteria developed in [9] and apply the result to the case of the fractional Laplacian (−Δ)α/2 where α ∈ (0, 2). We prove weighted Lp estimates for the semigroups generated by H0 = (−Δ)α/2 and H0 + V . These estimates are used for the verification of the semigroup criteria. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Graded rings and equivariant sheaves on toric varieties
Authors: Perling Markus 
Published: December 2003

AbstractIn this note we derive a formalism for describing equivariant sheaves over toric varieties. This formalism is a generalization of a correspondence due to Klyachko, which states that equivariant vector bundles on toric varieties are equivalent to certain sets of filtrations of vector spaces. We systematically construct the theory from the point of view of graded ring theory and this way we clarify earlier constructions of Kaneyama and Klyachko. We also connect the formalism to the theory of fine‐graded modules over Cox' homogeneous coordinate ring of a toric variety. As an application we construct minimal resolutions of equivariant vector bundles of rank two on toric surfaces. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Absolute continuity of autophage measures on finite‐dimensional vector spaces
Authors: Raja C. R. E. 
Published: December 2003

AbstractWe consider a class of measures called autophage which was introduced and studied by Szekely for measures on the real line. We show that the autophage measures on finite‐dimensional vector spaces over real or Qp are infinitely divisible without nontrivial idempotent factors and are absolutely continuous with bounded continuous density. We also show that certain semistable measures on such vector spaces are absolutely continuous. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Polynomial growth solutions of Sturm‐Liouville equations on a half‐line and their zero distribution
Authors: Shin Chang Eon , Tovbis Alexander , Zayed Ahmed I. 
Published: December 2003

AbstractFor α ∈ [0, 2π], consider the Sturm‐Liouville equation on the half liney″(x) + (λ − q(x))y(x) = 0,  0 ≤ x < ∞,withy(0) = sinα,  y′(0) = −cosα.For each λ > 0, denote by ϕ(x, λ) the solution of the above initial‐value problem. It is known that the condition xq(x) ∈ L1(ℝ+) is sufficient for ϕ(x, λ) to be uniformly bounded by a linear function in x for all x, λ ≥ 0; however, this condition is not necessary as the Bessel differential equation demonstrates. In this paper we extend this result to the borderline case in which q(x) = O(1/x2) as x → ∞. We show that if q(x) is continuously differentiable and q(x) = O(1/x2) as x → ∞, that is, xq(x) may not be integrable on ℝ+, then there exists a polynomial p(x) such that|ϕ(x, λ)| ≤ p(x)  for any  x ∈ [0,∞) and λ ∈ [0,∞).As a particular example, we consider the perturbed Bessel equation

where ν ∈ ℝ and h(x) = o(1/x2) as x → ∞. The technique, developed in the paper, allows us to find upper and lower bounds on the distance between consecutive zeroes xn, xn+1 of the solution v(x) of the perturbed Bessel equation, as well as the asymptotics of xn+1 − xn as n → ∞. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of the Helical Backbone in the Behavior of a Simple Model for Dimeric Coiled‐Coil Proteins
Authors: Prieto Lidia , Rey Antonio 
Published: December 2003

AbstractUsing computer simulations as a tool for thought experiments, we investigate the influence of the helical backbone geometry in the association process and the final structures of a simple model which mimics parallel, two‐stranded coiled‐coil proteins. We define three types of helices: two of them have straight helical axes and 3.5 or 3.6 residues per helical turn; the third type presents a coiled helical axis, according to the canonical scheme defined by Crick. By using a Monte Carlo simulation algorithm, we observe that the three models exhibit different transition temperatures for the formation of the dimeric structure from two independent peptides, and a different behavior concerning the appearance of out‐of‐register structures. The energy minimized dimer structures present strong deviations from the correct association for straight helices with 3.6 residues/turn, especially for long peptides, deviations which are absent for the other two types when only the burial of hydrophobic residues is considered. A careful analysis of the energies for the out‐of‐register configurations and the contact maps reveals also differences between dimers resulting from the model with Crick parameterization and with 3.5 residues/turn. The results presented in this paper may be relevant for the design of simple models which use rigid α‐helices built from predicted elements of secondary structure.Top views of the helical models used in this work.imageTop views of the helical models used in this work.
Inverse problem for a perturbed stratified strip in two dimensions
Authors: Cristofol Michel , Gaitan Patricia 
Published: December 2003

AbstractWe consider the divergence form elliptic operator A=−∇x,z·(c2(x,z) ∇x,z) in the strip Ω=ℝ× [0,H]. The velocity c(x,z) describes the multistratification of Ω: a horizontal stratification with a compact perturbation K, the velocity in K is a L∞(K) function. We suppose that the position of the perturbation is known and we prove uniqueness for identification of the perturbation from one generalized eigenfunction pattern in the neighbourhood of K. Copyright © 2004 John Wiley & Sons, Ltd.
Sufficient conditions of non‐uniqueness for the Coulomb friction problem
Authors: Hassani Riad , Hild Patrick , Ionescu Ioan 
Published: December 2003

AbstractWe consider the Signorini problem with Coulomb friction in elasticity. Sufficient conditions of non‐uniqueness are obtained for the continuous model. These conditions are linked to the existence of real eigenvalues of an operator in a Hilbert space. We prove that, under appropriate conditions, real eigenvalues exist for a non‐local Coulomb friction model. Finite element approximation of the eigenvalue problem is considered and numerical experiments are performed. Copyright © 2003 John Wiley & Sons, Ltd.
Galerkin method for optimal control of second‐order evolution equations
Authors: Dȩbińska‐Nagórska Anna , Just Andrzej , Stempień Zdzisaw 
Published: December 2003

AbstractThis paper presents the Galerkin approximation of the optimization problem of a system governed by non‐linear second‐order evolution equation where a non‐linear operator depends on derivative of the state of the system. The control is acting on a non‐linear equation. After giving some results on the existence of optimal control we shall prove the existence of the weak and strong condensation points of a set of solutions of the approximate optimization problems. Each of these points is a solution of the initial optimization problem. Finally we shall give a simple example using the obtained results. Copyright © 2004 John Wiley & Sons, Ltd.
Capacitation of mammalian spermatozoa in vivo, with a specific focus on events in the fallopian tubes
Authors: Hunter R.H.F. , Rodriguez‐Martinez H. 
Published: December 2003

AbstractThis essay argues strongly that for those sperm cells involved in fertilisation, the process of capacitation represents an active and specific coordination within succeeding regions of the female tract and one whose completion is synchronised with the events of ovulation. Observations on the time‐course of capacitation when spermatozoa are first exposed to the uterus and then progress to the Fallopian tubes indicate a synergistic influence of these adjoining portions of the female tract on the rate of capacitation. Three concepts on the control of capacitation are introduced to emphasise the importance of integration in vivo, namely that (1) completion of capacitation is a peri‐ovulatory event, (2) suppression of completion of capacitation is an essential storage strategy during a long pre‐ovulatory interval, and (3) the process of capacitation comes under the influence of local and systemic ovarian control mechanisms, especially the secretion of progesterone from Graafian follicles soon to ovulate. The last would act to coordinate the final maturation and meeting of male and female gametes. Despite the preceding points, the requirement for such integrated in vivo programming of sperm cell maturation can clearly be overridden in systems of culture. The most reasonable interpretation here would be that a microdrop of culture medium containing eggs, follicular cells and components of follicular fluid would to a considerable extent represent a post‐ovulatory environment. Within such a preparation, there would be leaching of the sperm surface among the relatively vast and heterogeneous population of cells, and a proportion of spermatozoa could then respond to ‘post‐ovulatory signals’, not least to molecular influences of the zona pellucida and vitelline products for completion of capacitation. Nonetheless, a physiologically meaningful interpretation of capacitation calls for a stepwise analysis of the dynamic interactions between sperm cell and female tract at successive stages between the uterus and ampullary‐isthmic junction. Mol. Reprod. Dev. 67:243–250, 2004. © 2004 Wiley‐Liss, Inc.
Activity of an enzyme converting single‐chain tissue‐type plasminogen activator to the two‐chain form in preovulatory human follicular fluid
Authors: Ohnishi Junji , Yokota Jyunko , Rajapakse R.G.S.C. , Ohnishi Eriko , Kudo Takayuki , Wada Shin‐Ichiro , Takahashi Takayuki 
Published: December 2003

AbstractThe biological role of the tissue‐type plasminogen activator (tPA)/plasmin system has long been implicated in ovarian function. We have recently shown that the follicular fluid of human ovaries contains an α2‐macroglobulin/protease complex capable of converting single‐chain (sc) tPA to the two‐chain (tc) enzyme tPA, suggesting the occurrence of its corresponding enzyme in a free form in the fluid. The aim of the current study is therefore to gain further information about the putative sctPA‐converting enzyme present in follicular fluid. Incubation of human recombinant sctPA with the fluid brought about the production of tctPA. It was also demonstrated that tctPA production resulted in the activation of endogenous fluid plasminogen. Production of tctPA and plasmin both was strongly inhibited by aprotinin, suggesting that the enzyme is a serine protease. The sctPA‐converting enzyme was partially purified from the fluid by column chromatographies. The enzyme preferably hydrolyzed synthetic peptide substrates containing arginine at the P1 position. The enzyme preparation had a protease inhibitor profile similar to that observed with the crude fluid sample. These results clearly demonstrated that follicular fluid contains an enzyme capable of efficiently converting sctPA to tctPA. Discovery of this sctPA‐converting enzyme strongly suggests that the tPA/plasmin system in the preovulatory follicle of human ovaries is operated through the proteolytic conversion of sctPA to tctPA rather than being regulated by a fibrin‐dependent mechanism. Mol. Reprod. Dev. 67:178–185, 2004. © 2004 Wiley‐Liss, Inc.
Mitochondrial DNA heteroplasmy in calves cloned by using adult somatic cell
Authors: Han Zhi‐Ming , Chen Da‐Yuan , Li Jin‐Song , Sun Qing‐Yuan , Wan Qiu‐Hong , Kou Zhao‐Hui , Rao Gang , Lei Lei , Liu Zhong‐Hua , Fang Sheng‐Guo 
Published: December 2003

AbstractAdult somatic cell cloned calves were produced by somatic cell nuclear transfer prepared by fusion of cultured ear fibroblast from a Holstein cow into enucleated oocytes of Luxi Yellow cow. In order to determinate the source of mitochondrial DNA of cloned calves, we designed the breed‐specific PCR primers by aligning the known D‐loop sequences of Bos taurus and analyzed the displacement loop sequences of five live cloned calves by breed‐specific primers PCR. The results demonstrated that mtDNA originated from Holstein breed and that from Luxi breed co‐exist in all five live calves. Mol. Reprod. Dev. 67:207–214, 2004. © 2004 Wiley‐Liss, Inc.
Intracarpal steroid injection is safe and effective for short‐term management of carpal tunnel syndrome
Authors: Armstrong Timothy , Devor William , Borschel Laura , Contreras Richard 
Published: December 2003

AbstractA double‐blinded placebo‐controlled trial was performed to evaluate the use of steroid injections beneath the transverse carpal ligament in the treatment of carpal tunnel syndrome (CTS) refractory to nonsurgical therapy. Forty‐three patients received 6 mg betamethasone and lidocaine and 38 patients received 1 ml saline placebo and lidocaine. The primary outcome measure was satisfaction with symptom relief. Thirty patients (70%) in the steroid‐treated group were satisfied or highly satisfied compared with 13 (34%) of placebo‐treated patients (P < 0.001). Patients receiving steroids also showed significant improvement in median nerve conduction parameters and scores on validated symptom/function questionnaires. Forty‐six patients were treated with serial injections for recurrent CTS symptoms. After 18 months, 17 patients reported adequate symptom relief with steroid injection, and 18 patients with unsatisfactory symptom relief were referred for carpal tunnel release surgery. We conclude that although steroid injections are safe and effective for temporary relief of CTS, most patients will eventually require surgery for long‐term control of their symptoms. Muscle Nerve 29: 82–88, 2003