bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surveillance of measles in the Sudan using filter paper blood samples
Authors: Mubarak H.S. El , Yüksel S. , Mustafa O.M. , Ibrahim S.A. , Osterhaus A.D.M.E. , de Swart R.L. 
Published: June 2004

AbstractDried blood spots collected on filter paper are considered potential clinical specimens for measles surveillance because of their ease of collection, storage, and transport. The usefulness of these samples for surveillance of measles was evaluated in a field setting. Blood spots were collected by finger‐prick from 316 clinically diagnosed measles patients in suburban Khartoum, mostly within a week after onset of the rash. Samples were collected between October, 2000 and April, 2003, and stored at 4°C. Measles virus‐specific IgM antibodies were detected in 200 (63%) of the samples using an “in‐house” IgM capture ELISA. For 201 samples reconstitution and IgM measurement was repeated 1 year after initial testing with essentially the same results, showing the stability of IgM in the filter paper under these conditions. In a limited number of samples (n = 38) measles virus‐specific IgM was also tested with a commercial indirect IgM ELISA. Although the results of the two assays correlated well, the “in‐house” IgM capture ELISA proved slightly more sensitive. Measles virus‐specific reverse transcriptase polymerase chain reaction (RT‐PCR) amplicons were obtained from 16 of 57 (28%) samples tested. Sequencing of the 3′ 456 nucleotides of the nucleoprotein gene showed the continued endemic circulation of genotype B3 viruses identified previously in this region. Although problems related to limited sample quantities were encountered, the present study confirms the usefulness of dried blood spots for measles surveillance. The results also demonstrate that measles continues to be endemic in the Sudan. J. Med. Virol. 73:624–630, 2004. © 2004 Wiley‐Liss, Inc.
Reactive Compatibilization of PBT/EVA Blends with an Ethylene‐Acrylic Acid Copolymer and a Low Molar Mass Bis‐Oxazoline
Authors: Scaffaro Roberto , La Mantia Francesco P. , Castronovo Claudia 
Published: June 2004

AbstractSummary: Polyesters and polyolefins form highly incompatible blends with poor properties and gross morphology that hinder any practical applications. In this work, the possibility to compatibilize an incompatible blend of poly(butylene terephthalate) (PBT) with ethylene vinyl acetate (EVA) by adding a bis‐oxazoline compound, 2,2′‐(1,3‐phenylene)‐bis(2‐oxazoline) (PBO), and an ethylene acrylic acid copolymer (EAA) as compatibilizer precursors has been studied. The results indicate that the binary uncompatibilized blends show poor mechanical properties and a bad morphology with scarce adhesion between the phases. The situation is only slightly improved when the EAA is added while the best performance is achieved when quaternary PBT/EVA/EAA/PBO blends are prepared. In this latter case the elongation at break and the impact strength are doubled and the morphology is deeply improved. The formation of EAA‐g‐(PBO)PBT copolymers in the presence of PBO can be invoked to explain the results and it is demonstrated that the eventual chain extension of PBT or EAA is negligible.SEM micrograph of a quaternary PBT/EVA/EAA/PBO blend.magnified imageSEM micrograph of a quaternary PBT/EVA/EAA/PBO blend.
On the Theoretical and Numerical Modelling of Unsaturated Soil
Authors: Graf Tobias , Ehlers Wolfgang 
Published: June 2004

AbstractIn this contribution, unsaturated soil is treated within the framework of the Theory of Porous Media (TPM). Therein, unsaturated soil can be described by a triphasic model consisting of a materially incompressible, elasto‐plastic or elasto‐viscoplastic solid skeleton, a viscous, materially incompressible pore‐liquid (water) and a viscous, materially compressible pore‐gas (air). The interaction between the solid skeleton and the pore‐fluids are taken into account by a capillary‐pressure‐saturation relation and a Darcy‐like filter law including relative permeabilities to consider the interaction between the two pore‐fluids. The resulting system of strongly coupled differential‐algebraic equations is solved for a gravity driven initial‐boundary‐value problem by the finite element tool PANDAS.
On some projections of homogenised coefficients for stationary diffusion equation
Authors: Antonić Nenad , Vrdoljak Marko 
Published: June 2004

AbstractThe set 𝒦(θ) of all composite materials obtained by mixing two isotropic phases (with given local proportion θ of the .rst material), in a stationary di.usion problem, is considered. The question of describing two columns of these matrices, or more precisely the set {(Ae, Af) : A ∈ 𝒦(θ)}, for two vectors e and f, is addressed.
Reliability of Structures in High Dimensions
Authors: Koutsourelakis P.S. , Pradlwarter H.J. , Schuëller G.I. 
Published: June 2004

AbstractA novel simulation procedure for the estimation of structural reliability is outlined. It is based on a stepwise algorithm which exhibits convergence rates that are independent of the dimensionality of the problem and outperform direct Monte Carlo as well as existing methods ([2]).
Successful treatment of severe aplastic anemia in children using standardized immunosuppressive therapy with antithymocyte globulin and cyclosporine A
Authors: Goldenberg Neil A. , Graham Douglas K. , Liang Xiayuan , Hays Taru 
Published: June 2004

AbstractBackgroundGiven the heterogeneity of published data in US children, we sought to evaluate outcomes of a standardized immunosuppressive therapy (IST) regimen for severe aplastic anemia (SAA) at The Children's Hospital (Denver, CO).MethodsWe retrospectively analyzed the records of 16 children diagnosed from 1990 to 2003 and treated by IST, among whom 14 received the standardized regimen of antithymocyte globulin (ATG) and cyclosporine A (CsA). Serial hematologic parameters, complications, transfusion requirements, and time to response were assessed.ResultsOne child who died from a pre‐existing Aspergillus infection prior to expected IST response was excluded from the analysis. Overall (transfusion‐independent) response to IST was 100% (13/13), without any relapses or clinically evident leukemic/myelodysplastic transformations after a median follow‐up time of 4.4 years (range: 10 months–13.3 years).ConlusionsThis report documents excellent outcome using combination ATG and CsA IST for pediatric SAA. © 2004 Wiley‐Liss, Inc.
Cure kinetics of epoxy resin used for advanced composites
Authors: Du Shanyi , Guo Zhan‐Sheng , Zhang Boming , Wu Zhanjun 
Published: June 2004

AbstractThe cure kinetics of an epoxy resin used for the preparation of advanced polymeric composite structures was studied by isothermal differential scanning calorimetry (DSC). A series of isothermal DSC runs provided information about the kinetics of cure over a wide temperature range. According to the heat evolution behavior during the curing process, several influencing factors of isothermal curing reactions were evaluated. The results showed that the isothermal kinetic reaction of this epoxy resin followed an autocatalytic kinetic mechanism. In the latter reaction stage, the curing reaction became controlled mainly by diffusion. Cure rate was then modeled using a modified Kamal autocatalytic model that accounts for the shift from a chemically controlled reaction to a diffusion‐controlled reaction. The model parameters were determined by a nonlinear multiple regression method. Copyright © 2004 Society of Chemical Industry
Random copolymerization of 2,2‐dimethyltri methylene carbonate and ε‐caprolactone using a rare‐earth tris(4‐tert‐butylphenolate)s as a single‐component initiator
Authors: Yu Cuiping , Zhang Lifang , Shen Zhiquan 
Published: June 2004

AbstractHighly random copolymers of 2,2‐dimethyltrimethylene carbonate (DTC) and ε‐caprolactone (CL) were synthesized by single component rare‐earth tris(4‐tert‐butylphenolate)s [Ln(OTBP)3] for the first time. The influences of reaction conditions on the copolymerization initiated by La(OTBP)3 have been examined in detail. The monomer reactivity ratios of DTC and CL determined by the Fineman–Ross method are 4.0 for rDTC and 0.27 for rCL. The microstructure of the copolymer was determined by the analyses of the diads DTC–DTC, DTC–CL, CL–DTC and CL–CL of the 1H NMR spectra. The high degree of randomness of the chain structure was further confirmed by the 13C NMR spectra and differential scanning calorimetry. The thermal properties of the copolymers as a function of composition are reported. The mechanism investigated by 1H NMR data indicates that the rare‐earth tris(4‐tert‐butylphenolate)s initiate the ring‐opening copolymerization of DTC and CL with acyl‐oxygen bond cleavages of the monomers. Copyright © 2004 Society of Chemical Industry
Electrochemical polymerization of chiral pyrrole derivatives in electrolytes containing chiral camphor sulfonic acid
Authors: Han GY , Shi GQ , Qu LT , Yuan JY , Chen FE , Wu PY 
Published: June 2004

AbstractN‐Substituted pyrrole derivatives with chiral side groups have been synthesized and electrochemically polymerized in acetonitrile containing tetrabutylammonium perchlorate (TBAClO4) and (S)‐(+)‐camphor‐10‐sulfonic acid ((S)‐(+)‐CSA) or (R)‐(−)‐camphor‐10‐sulfonic acid ((R)‐(−)‐CSA). The resulting N‐substituted polypyrrole films were characterized by cyclic voltammetry, infrared, Raman and X‐ray photoelectron (XPS) spectroscopies. XPS results demonstrated that the as‐grown polymer films are preferably doped by CSA anions when the monomer and the CSA anion have the same optical rotation dispersion (ORD). Furthermore, the conductivities of the polymers synthesized in the media containing CSA with the same ORD of the corresponding monomers were measured to be about 2–10 times higher than those of polymers obtained from electrolytes without CSA. Copyright © 2004 Society of Chemical Industry
Fluorinated polymers as stone‐protective materials: an FTIR study on intermolecular interactions
Authors: D'Alessio Aldo , Turchi Fabrizia , Narducci Piero , Vergamini Piergiorgio , Ciardelli Francesco , Catanorchi Stefano 
Published: June 2004

AbstractAttempts have been performed to obtain spectroscopic evidence of intermolecular interactions between fluorinated polymers to be used as protective materials and various stones. In this paper we report an investigation by means of FTIR spectroscopy on poly(vinyl fluoride)(PVF) which contains acid hydrogens that can give rise to intermolecular interactions with calcium carbonate. Spectral changes have been found in the CH and CF stretching regions at 3000–2840 and 1200–950 cm−1, respectively. These last are attributed to intermolecular interactions of the polymer with CO32− and with conformational changes of the macromolecular chain. Scanning electron microscopy investigations were also performed on marble slabs coated with a PVF film in order to gain information about the morphology of the polymer film. Copyright © 2004 Society of Chemical Industry
Hyperbranched polyesters of 3,5‐diacetoxybenzoic acid: A reinvestigation
Authors: Kricheldorf Hans R. , Hobzova Radka , Schwarz Gert , Schultz Claus‐Ludolf 
Published: June 2004

Abstract3,5‐Diacetoxybenzoic acid was polycondensed at temperatures in the range of 200–250 °C either in the absence of a catalyst or with addition of MgO or SnCl2. The highest molecular weight was obtained in the absence of a catalyst. The matrix‐assisted laser desorption/ionization time‐of‐flight mass spectra revealed the formation of cyclic hyperbranched polyesters. The content of polyesters with cyclic core increased with higher conversions, and thus, with higher molecular weights. Furthermore, a loss of acetyl groups was found to be a significant side reaction. The same side reactions were found when trimethylsilyl 3,5‐bisacetoxybenzoate was polycondensed at 280 or 310 °C. Model reactions concerning the deacetylation mechanism were performed and the results are discussed. Size exclusion chromatography measurements in two different solvents proved that the high‐molecular‐weight fraction is not the result of aggregation via hydrogen bonds. Yet, the nature of the solvent, the profile of the columns, and the character of the detector had a significant influence on the shape of the elution curves and on the apparent molecular weights. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3751–3760, 2004
Living ring‐opening polymerization of lactides catalyzed by guanidinium acetate
Authors: Li Hong , Wang Chenhong , Yue Jin , Zhao Xiaona , Bai Feng 
Published: June 2004

AbstractHexabutyl guanidinium acetate (HBG · OAc) was synthesized and successfully used as a catalyst for the ring‐opening polymerization (ROP) of lactides. The experimental results indicated that the guanidinium salt HBG · OAc showed satisfactory catalytic behavior. Polymerization in bulk (120 °C, 18 h) produced polylactides with moderate molecular weights (number‐average molecular weight = 2.0 × 104) and very narrow molecular weight distributions (polydispersity index = 1.07–1.12). A kinetic study of polymerization in bulk with HBG · OAc as an initiator revealed that the polymerization possessed typical characteristics of living polymerization. A ROP mechanism by HBG · OAc was proposed on the basis of the additive effect of the polymerization and the 1H NMR characterization of the microstructure of the product polymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3775–3781, 2004
Statistical thermodynamics evaluation of polymer–polymer miscibility
Authors: Utracki L. A. 
Published: June 2004

AbstractThe Simha and Somcynsky (S–S) statistical thermodynamics theory was used to compute the solubility parameters as a function of temperature and pressure [δ = δ(T, P)], for a series of polymer melts. The characteristic scaling parameters required for this task, P*, T*, and V*, were extracted from the pressure–temperature–volume (PVT) data. To determine the potential polymer–polymer miscibility, the dependence of δ versus T (at ambient pressure) was computed for 17 polymers. Close proximity of the δ versus T curves for four miscible polymer pairs: PPE/PS, PS/PVME, and PC/PMMA signaled the usefulness of this approach. It is noteworthy, that the tabulated solubility parameters (derived from the solution data under ambient conditions) propounded the immiscibility of the PVC/PVAc pair. The computed values of δ also suggested miscibility for polymer pairs of unknown miscibility, namely PPE/PVC, PPE/PVAc, and PET/PSF. In recognizing the limitations of the solubility parameter approach (the omission of several thermodynamic contributions), these preliminary results are auspicious because they indicate a new route for estimating the miscibility of any polymeric material at a given temperature and pressure. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2909–2915, 2004
β‐Hairpin conformation of fibrillogenic peptides: Structure and α‐β transition mechanism revealed by molecular dynamics simulations
Authors: Daidone Isabella , Simona Fabio , Roccatano Danilo , Broglia Ricardo A. , Tiana Guido , Colombo Giorgio , Di Nola Alfredo 
Published: June 2004

AbstractUnderstanding the conformational transitions that trigger the aggregation and amyloidogenesis of otherwise soluble peptides at atomic resolution is of fundamental relevance for the design of effective therapeutic agents against amyloid‐related disorders. In the present study the transition from ideal α‐helical to β‐hairpin conformations is revealed by long timescale molecular dynamics simulations in explicit water solvent, for two well‐known amyloidogenic peptides: the H1 peptide from prion protein and the Aβ(12–28) fragment from the Aβ(1–42) peptide responsible for Alzheimer's disease. The simulations highlight the unfolding of α‐helices, followed by the formation of bent conformations and a final convergence to ordered in register β‐hairpin conformations. The β‐hairpins observed, despite different sequences, exhibit a common dynamic behavior and the presence of a peculiar pattern of the hydrophobic side‐chains, in particular in the region of the turns. These observations hint at a possible common aggregation mechanism for the onset of different amyloid diseases and a common mechanism in the transition to the β‐hairpin structures. Furthermore the simulations presented herein evidence the stabilization of the α‐helical conformations induced by the presence of an organic fluorinated cosolvent. The results of MD simulation in 2,2,2‐trifluoroethanol (TFE)/water mixture provide further evidence that the peptide coating effect of TFE molecules is responsible for the stabilization of the soluble helical conformation. Proteins 2004. © 2004 Wiley‐Liss, Inc.
Glycine N‐methyltransferases: A comparison of the crystal structures and kinetic properties of recombinant human, mouse and rat enzymes
Authors: Pakhomova Svetlana , Luka Zigmund , Grohmann Steffi , Wagner Conrad , Newcomer Marcia E. 
Published: June 2004

AbstractGlycine N‐methyltransferases (GNMTs) from three mammalian sources were compared with respect to their crystal structures and kinetic parameters. The crystal structure for the rat enzyme was published previously. Human and mouse GNMT were expressed in Escherichia coli in order to determine their crystal structures. Mouse GNMT was crystallized in two crystal forms, a monoclinic form and a tetragonal form. Comparison of the three structures reveals subtle differences, which may relate to the different kinetic properties of the enzymes.The flexible character of several loops surrounding the active site, along with an analysis of the active site boundaries, indicates that the observed conformations of human and mouse GNMTs are more open than that of the rat enzyme. There is an increase in kcat when going from rat to mouse to human, suggesting a correlation with the increased flexibility of some structural elements of the respective enzymes.Proteins 2004, © 2004 Wiley‐Liss, Inc.
Kinetics of folding and unfolding of goat α‐lactalbumin
Authors: Chedad Allel , Van Dael Herman 
Published: June 2004

AbstractThe equilibrium unfolding and the kinetic folding and unfolding of goat α‐lactalbumin (GLA) were studied by near‐ and far‐ultraviolet circular dichroism (CD) and by stopped‐flow fluorescence spectroscopy. Specifically, the influence of environmental conditions such as pH and Ca2+ binding was examined. Compared to the apo‐form, the Ca2+‐bound form was found to be strongly stabilized in equilibrium conditions at pH 7.5 and 25°C. The kinetics of the refolding of apo‐GLA show a major change of fluorescence intensity during the experimental dead‐time, but this unresolved effect is strongly diminished in holo‐GLA. In both cases, however, the chevron plots can adequately be fitted to a three‐state model. Moreover, double‐mix stopped‐flow experiments showed that the native state (N) is reached through one major pathway without the occurrence of alternative tracks. In contrast to the homologous bovine α‐lactalbumin (BLA), the compactness of GLA is strongly influenced by the presence of Ca2+ ions. Unlike the two‐state transition observed in guanidine hydrochloride (GdnHCl)‐induced equilibrium denaturation experiments at higher pH, an equilibrium intermediate state (I) is involved in denaturation at pH 4.5. In the latter case, analysis of the kinetic data makes clear that the intermediate and the unfolded states (U) show practically no Gibbs free energy difference and that they are in rapid equilibrium with each other. A possible explanation for these variations in stability and in folding characteristics with pH could be the degree of protonation of His107 that directly influences non‐native interactions. Variation of environmental conditions and even small differences in sequence, therefore, can result in important effects on thermodynamic and folding parameters. Proteins 2004. © 2004 Wiley‐Liss, Inc.
Spectral and magnetic properties of the t–J model of cuprate perovskites
Authors: Sherman A. 
Published: June 2004

AbstractThe use of the t–J model of Cu–O planes and projection operator technique for the Hubbard operators allows us to take proper account of strong electron correlations inherent in cuprate high‐Tc superconductors. A number of unusual properties of cuprates can be reproduced in this approach. Among them are the peculiarities of the temperature and concentration dependencies of the spin‐lattice relaxation and spin‐echo decay rates, the resonance peak and the incommensurate low‐frequency magnetic response in neutron scattering. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Identification and characterization of a novel allosteric modulator (SoRI‐6238) of the serotonin transporter
Authors: Nandi Ayon , Dersch Christina M. , Kulshrestha Manish , Ananthan Subramaniam , Rothman Richard B. 
Published: June 2004

AbstractIn the present study we describe a novel agent, SoRI‐6238 (ethyl 5‐amino‐3‐(3,4‐dichlorophenyl)‐1,2‐dihydropyrido[3,4‐b]pyrazin‐7‐ylcarbamate) that partially inhibits 5‐HT transporter (SERT) binding and allosterically modulates SERT function. Membranes were prepared from rat brain. SoRI‐6238 partially inhibited SERT binding to brain membranes with a plateau at about 40% of control. SoRI‐6238 fully inhibited norepinephrine transporter (NET) and dopamine transporter (DAT) binding with IC50 values of 12.1 μM and 5.8 μM, respectively. The apparent Kd of [125I]RTI‐55 binding to SERT increased, then reached a plateau with increasing concentrations of SoRI‐6238. SoRI‐6238 fully inhibited [3H]5‐HT uptake, acting to decrease the Vmax (noncompetitive inhibition). In kinetic experiments, SoRI‐6238 slowed the dissociation of [125I]RTI‐55 from SERT and slowed the initial association rate. We conclude that SoRI‐6238 partially inhibits SERT binding and function, most likely via an allosteric mechanism. Synapse 53:176–183, 2004. © 2004 Wiley‐Liss, Inc.
Specification and analysis of synchronous reactions
Authors: Nebut Mirabelle 
Published: June 2004

Abstract.
Development environments based on the synchronous paradigm do not offer many validation tools dedicated to numerical aspects, while various techniques are well known. Actually it appears that in the most general case models are extended with a special value that makes explicit the absence of discrete events at a given instant, which prevents from directly taking advantage of existing methods. This paper deals with absence handling in the context of the synchronous paradigm. With this focus it first surveys the main languages and stresses the importance of clocks, then it discusses our “Clock Language” that makes possible the handling of numerical aspects without explicit absence.