bluuebunny/crossref_metadata_2025_split huggingface dataset:
Incidence and characteristics of endemic Norwalk‐like virus‐associated gastroenteritis
Authors: Marshall John A. , Hellard Margaret E. , Sinclair Martha I. , Fairley Christopher K. , Cox Bradley J. , Catton Michael G. , Kelly Heath , Wright Peter J. 
Published: February 2003

AbstractEndemic gastroenteritis associated with the Norwalk‐like viruses (NLVs) is little understood. This study tested for NLV in gastroenteritis cases in 257 households in Melbourne, Australia, for the period September 1997 to February 1999 by a reverse transcription hemi‐nested polymerase chain reaction. Positive samples were studied by nucleotide sequencing and phylogenetic analysis. NLV was detected in 73 (11.4%) of 638 faecal specimens tested. Twelve (1.9%) were NLV genogroup 1 (G1) and 61 (9.6%) NLV genogroup 2 (G2). Gastroenteritis symptoms associated with NLV G2/no other pathogens were significantly more severe than where no NLV was detected. NLV G1 and NLV G2 were detected in adults and children, males and females. NLV G2 incidence showed a marked seasonal periodicity with significant peaks in the Australian late spring/early summer periods. NLV G1 seasonality was significantly different from that of NLV G2. Seven major NLV clusters were identified by phylogenetic analysis. J. Med. Virol. 69:568–578, 2003. © 2003 Wiley‐Liss, Inc.
Epidemiological features of rotavirus infection among hospitalized children with gastroenteristis in Ho Chi Minh City, Vietnam
Authors: Doan Lan Thi Phuong , Okitsu Shoko , Nishio Osamu , Pham Dung Trung , Nguyen Dung Hoang , Ushijima Hiroshi 
Published: February 2003

AbstractAn epidemiological study of the G serotype and P genotype distribution of group A rotaviruses by using ELISA and/or RT‐PCR was conducted in children (aged 1 month to 15 years) with diarrhea that were admitted to the General Children's Hospital No. 1, Ho Chi Minh City, Vietnam from December 1999 to November 2000. The results showed that rotavirus is associated with 65.6% (889/1355) of diarrheal admissions. Rotavirus infection mostly affected children under 2 years of age with a peak incidence in children 1 to 2 years of age (75.7%) and it occurs year round with a slight seasonal pattern; 99.5% of the specimens could be G‐typed: G1 was predominant (68.7%), followed by G4 (15.4%), G2 (12.3%), G3 (0.6%), and G9 (0.5%). High identities of VP7 nucleotide (96.3 to 96.9%) and deduced amino acid (98.1 to 98.4%) were found between two Vietnamese G9 strains and also the recent emergence of G9 strains US 1205, Brazilian R143, and Malawian MW69. Mixed infections were identified in 17 (2.0%), and 5 strains (0.5%) remained untypable. The four most common worldwide strains, G1P[8], G2P[4], G3P[8], and G4P[8], constituted 81.1% of all rotaviruses typed with G1P[8] being the most prevalent type (58.2%). Unusual G/P combinations (11 strains) were detected in 11.7% of all strains, of which, G1P[4] was the most prevalent, accounting for 5.6% of the total. Several combinations of G and P types were observed in this study, suggesting a complex rotavirus infection pattern in Vietnam. This study has provided for the first time clear indication on the circulating G and P genotypes among hospitalized children in Ho Chi Minh City, Vietnam. The results suggest that these viral infections are prevalent among hospitalized children and that the four most common worldwide G types as well as the four most common G‐P combinations were also infecting children in Ho Chi Minh City, Vietnam. This result could have important implications for rotavirus vaccine programs and for understanding the epidemiological characteristics of human rotavirus in Ho Chi Minh City, Vietnam. J. Med. Virol. 69:588–594, 2003. © 2003 Wiley‐Liss, Inc.
Antibody response after RSV infection in children younger than 1 year of age living in a rural area of Mozambique
Authors: Roca Anna , Quintó Llorenç , Abacassamo Fátima , Loscertales Maria Paz , Gómez‐Olivé Francesc Xavier , Fenwick Fiona , Cane Patricia A. , Saiz Juan Carlos , Toms Geoffrey , Alonso Pedro L. 
Published: February 2003

AbstractSerological responses have been studied in respiratory syncytial virus (RSV) infected children  < 1 year of age attending the outpatient department of the Manhiça District Hospital (Mozambique). Molecular characterization of viral RNA in nasopharyngeal aspirates from the infected children indicated a high level of genetic uniformity among the infecting viruses, all of which belonged to a single genotype of RSV group A. A representative virus strain, Moz00, was isolated from one of the infants and was used, together with the group A strain A2 and the group B strain 8/60, as antigens in the quantification of infant antibody responses. In this study, 97.5% (39/40) and 96.4% (27/28) of infected children produced an antibody response against Moz00 detected by the membrane fluorescent antibody test (MFAT) and the neutralization test (NT), respectively. Seroconversion rates decreased when the A2 and 8/60 strains were used as antigen in MFAT (95.4% and 88.2%, respectively) or NT (81.8% and 54.5%, respectively), indicating that antibody responses had both group‐ and strain‐specific components. Antibodies in convalescent sera of infected children were compared with maternally derived antibodies detected in a group of children also  < 1 year of age, but with no evidence of RSV infection. The convalescent sera exhibited reduced neutralizing capacity when the 8/60 strain was used as antigen (P = 0.028), suggesting that the infant antibody response lacks neutralizing capacity against strains of the heterologous virus group. Restricted cross‐reactivity and neutralizing capacity of antibodies generated by young children might be expected to induce only moderate protection in subsequent epidemics against genetically distant strains. J. Med. Virol. 69:579–587, 2003. © 2003 Wiley‐Liss, Inc.
Aqueous Gels of Diblock Oxyethylene‐Oxypropylene Copolymers
Authors: Kelarakis Antonis , Havredaki Vassiliki , Booth Colin 
Published: February 2003

AbstractAqueous solutions of diblock copolymers E102P37 and E92P55 (E = oxyethylene unit, P = oxypropylene unit) were investigated by rheometry. Storage (G′) and loss (G″) modulus and yield stress (σy) were used to detect and characterise hard and soft gels in experiments which covered the concentration range 4–28 wt.‐% copolymer and the temperature range 5–85 °C. Comparison is made with phase diagrams reported for other diblock copoly(oxyalkylene)s, and it is shown that the mesophase behaviour of these systems depends on the effective thickness of the E‐block corona and the stability of the micelles at low temperatures.
Hard‐gel boundaries (circles) and soft‐gel boundaries (squares) for aqueous solutions of copolymers (○, □) E92P55 and (•, ▪) E96B18.magnified imageHard‐gel boundaries (circles) and soft‐gel boundaries (squares) for aqueous solutions of copolymers (○, □) E92P55 and (•, ▪) E96B18.
Magnetic Polystyrene Nanoparticles with a High Magnetite Content Obtained by Miniemulsion Processes
Authors: Ramírez Liliana P. , Landfester Katharina 
Published: February 2003

AbstractThe encapsulation of high amounts of magnetite into polystyrene particles can efficiently be achieved by a new three‐step preparation route including two miniemulsion processes. In the first step, a dispersion of oleic acid coated magnetite particles in octane is obtained. In the second step, magnetite aggregates in water are produced in a miniemulsion process by using sodium dodecyl sulfate (SDS) as surfactant. In the third step, the dispersion with the magnetite aggregates which are covered by an oleic acid/SDS bilayer were mixed with a monomer miniemulsion and a second miniemulsion process, an ad‐miniemulsification process, is used to obtain full encapsulation. After polymerization, polymer encapsulated magnetite aggregates were obtained. Characterization by thermogravimetry, preparative ultracentrifugation, and transmission electron microscopy showed that up to 40% magnetite could be encapsulated resulting in particles with a high homogeneity of the magnetite content. Magnetometry measurements reveal that the included iron oxide aggregates still consist of separated superparamagnetic magnetite particles.
Transmission electron micrograph for magnetite polystyrene particles (Latex‐1).magnified imageTransmission electron micrograph for magnetite polystyrene particles (Latex‐1).
ADMET Polymerization as a Route to Functionalized Polycarbosilanes
Authors: Church A. Cameron , Pawlow James H. , Wagener K. B. 
Published: February 2003

AbstractIt is now evident that ADMET chemistry can be employed to prepare a family of unsaturated carbosilane polymers containing a common backbone decorated with different alkoxysilane pendant groups, demonstrating the generality and potential utility of this chemistry. Four functionalized silicon containing dienes have been synthesized by nucleophilic substitution of the same parent diene monomer containing two reactive silicon‐chlorine bonds. These new α,ω‐diene monomers have been polymerized under ADMET conditions using the 2nd generation Grubbs's ruthenium catalyst, producing polymers with useful molecular weights. Variation of the pendant group results in differing chemical and physical properties of the resulting polymers. We believe this chemistry offers much to broaden the synthetic pathways to new organosilicon polymers.
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Synthesis of π‐Conjugated Organometallic Polymer Networks
Authors: Kokil Akshay , Huber Christian , Caseri Walter R. , Weder Christoph 
Published: February 2003

AbstractThe present paper reports the synthesis of π‐conjugated organometallic polymer networks based on poly[2,5‐dioctyloxy‐1,4‐diethynyl‐phenylene‐alt‐2,5,‐bis(2′‐ethylhexyloxy)‐1,4‐phenylene] (EHO‐OPPE), a soluble poly(p‐phenylene ethynylene) (PPE) derivative. The ethynylene moieties of the polymer coordinate to Pt0 centers, which act as conjugated cross‐links. These materials are readily accessible through ligand‐exchange reactions between the linear PPE and Pt(styrene)3. The in‐situ NMR investigation of model reactions of Pt(styrene)3 with diphenylacetylene (DPA) has shown that the ethynylene moieties comprised in the PPE readily coordinate to Pt0 centers under release of the relatively weakly‐bound styrene ligands. Spin‐coating has resulted in cross‐linked films of good optical quality. We also have been able to produce PPE‐Pt‐gels with high solvent content (> 95 wt.‐%). As expected, the coordination of Pt markedly influences the photophysical characteristics of the PPE. The photoluminescence is efficiently quenched, and the absorption maximum in the visible regime experiences a hypsochromic shift.
Ligand‐exchange reaction between EHO‐OPPE and [Pt(PhCHCH2)3] leading to the target EHO‐OPPE‐Pt0 networks.magnified imageLigand‐exchange reaction between EHO‐OPPE and [Pt(PhCHCH2)3] leading to the target EHO‐OPPE‐Pt0 networks.
Synthesis, Structure and Properties of Melamine‐Based pTHF‐Urethane Supramolecular Compounds
Authors: Öjelund Karin , Loontjens Ton , Steeman Paul , Palmans Anja , Maurer Frans 
Published: February 2003

AbstractThe properties of melamine based supramolecular compounds have been studied with rheological, thermal, mechanical, dielectric and scattering techniques and compared with similar covalently bonded materials. The complexes are based on a linear pTHF‐diol (Mn = 1 000) connected via a diisocyanate with melamine. The results obtained show that, despite of the material's low molecular weight (< 2 000 g · mol−1), it has properties typical for high molar mass polymers. The material has a high modulus above the glass transition temperature, and shows behavior similar to a semi‐crystalline material. This is attributed to the presence of the hydrogen bonds, in combination with phase separation giving rise to hard domain formation. In comparison with a covalently bonded and a low molecular weight material of similar composition, the supramolecular compounds have a higher and more temperature dependent viscosity. By exchanging parts of the pTHF with a low molecular weight diol, in our case hexane diol, the mechanical properties at room temperature could be modified to a stiffer but more brittle material.
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Oligothiophenes for Pattern Formation by Stamping
Authors: Allard Sybille , Braun Lydia , Brehmer Martin , Zentel Rudolf 
Published: February 2003

AbstractOligothiophene monomers with a fixed length varying from 3 to 5 thiophene rings were prepared by Stille coupling. They were functionalised with one or two methacrylate groups to allow polymerization and cross‐linking. These monomers can be patterned with the help of soft silicon stamps (e.g., with the micro‐injection moulding in capillaries process) on substrates like glass or flexible polymer foils. If a photoinitiator has been added, they can then be hardened by exposure to UV‐light through the transparent stamp. Afterwards the stamp can be removed. This allows the preparation of several centimeters long oligothiophene lines of a width varying between 50 and 0.5 μm. These lines of semiconducting organic material can be used e.g., as an orientation layer for liquid crystals.
The resulting line patterns from embossing oligomer 17, line width 500 nm.magnified imageThe resulting line patterns from embossing oligomer 17, line width 500 nm.
Morphological Evolution of Polyoctenamer upon Photo‐Ageing
Authors: Commereuc Sophie , Svecova Lenka , Verney Vincent 
Published: February 2003

AbstractThe morphological structure evolutions of polyoctenamer upon photo‐ageing have been monitored with the aim of correlating the changes of the microstructure with our previous results concerning chemical and molecular evolutions. The influence of the experimental temperature of photo‐oxidation has been investigated with regard to the melting temperature of the different crystalline microphases. A critical point was clearly exhibited (10 h of UV exposure at 35 °C). Before this point the degradation occurs according an oxidative process and takes place only in the amorphous phases. During this period, the molecular structure changes to induce rapid cross‐linking. After the critical point, the chemical oxidation results from a photolytic process. The extent of the tridimensional network becomes invariant and imperfect crystalline zones are then affected.
Kinetic curves of the formation of carbonylated by‐products (□) and peroxidic species (▪) through photo‐oxidation of V6040 films (thickness about 100 μm) at λ > 300 nm at 35 °C.magnified imageKinetic curves of the formation of carbonylated by‐products (□) and peroxidic species (▪) through photo‐oxidation of V6040 films (thickness about 100 μm) at λ > 300 nm at 35 °C.
Thermo‐Responsive Organic/Inorganic Hybrid Hydrogels based on Poly(N‐vinylcaprolactam)
Authors: Loos Wouter , Verbrugghe Sam , Goethals Eric J. , Du Prez Filip E. , Bakeeva Irena V. , Zubov Vitali P. 
Published: February 2003

AbstractA new type of ‘intelligent’ hydrogels has been developed in the form of organic/inorganic hybrid materials by making use of the sol‐gel technology. Poly(N‐vinylcaprolactam) (PVCL) has been incorporated in these materials for its thermo‐responsive properties. The synthesis of the hybrid hydrogels was achieved by the in situ formation of an inorganic silica phase in the presence of an aqueous solution of high molecular weight PVCL. This methodology results in the preparation of micro‐heterogeneous systems in which silica particles of nanometer dimensions act as physical cross‐links for the PVCL molecules. Hydrogen bonds between the remaining non‐condensed silanol groups and the PVCL carbonyl functions, together with physical entanglements, are responsible for the strong interactions between the organic and inorganic phases. Stress‐strain tests on highly swollen materials demonstrated that the unique structure of these thermo‐responsive hybrid hydrogels improves the mechanical stability to a great extent as compared to conventional hydrogels. Transmission measurements demonstrate that the presence of the inorganic phase does not influence the cloud point temperatures of PVCL significantly. On the other hand, the response of the reinforced hybrid hydrogels to temperature becomes less pronounced for increasing silica fractions. The reversibility of the swelling/deswelling process has been demonstrated by swelling experiments as a function of temperature.
PVCL/SiO2 hybrid hydrogels.magnified imagePVCL/SiO2 hybrid hydrogels.
Novel Fluorinated Polymer by Radiation‐Induced Polyaddition of Bisperfluoroisopropenyl Terephthalate with 1,4‐Dioxane
Authors: Enomoto Kazuyuki , Narita Tadashi , Maekawa Yasunari , Yoshida Masaru , Hamana Hiroshi 
Published: February 2003

AbstractRadical polyaddition of bis(α‐trifluoromethyl‐β,β‐difluorovinyl) terephthalate [CF2C(CF3)OCOC6H4COOC(CF3)CF2] (BFP) with 1,4‐dioxane (DOX) was investigated under γ‐rays radiation from a 60Co source to produce higher molecular weight polymers compared to those yielded by benzoyl peroxide initiation. Prior to polyaddition, the addition reactions of 2‐benzoxypentafluoropropene [CF2C(CF3)OCOC6H5] (BPFP) with tetrahydrofuran (THF) and DOX, and BFP with THF were examined in order to develop probable polyaddition reaction conditions. The polymer bearing 1.5 × 104 as a molecular weight was obtained under the feed molar ratio of DOX/BFP = 16 with an irradiation dose of 2 000 kGy at 40 °C, which is a much higher molecular weight compared to that yielded by benzoyl peroxide.
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Determination of Polyisoprene‐block‐poly(methyl methacrylate) Domain Sizes Using 1H Spin Diffusion
Authors: Werkhoven Thekla M. , Mulder Fokko M. , Zune Catherine , Jérôme Robert , de Groot Huub J. M. 
Published: February 2003

AbstractThe microphase structure of polyisoprene‐block‐poly(methyl methacrylate) diblock copolymers was studied using solid‐state NMR techniques. Wideline separation spectroscopy reveals a narrow interphase between the two polymers. The domain sizes of a lamellar sample and a sample with hexagonally ordered cylinders were determined using 1H spin diffusion. The lamellar sample shows a domain size of 16 ± 2 nm for the minor polyisoprene phase and a long period of 33 ± 4 nm. The cylindrical structure has a long period of 38 ± 7 nm, the diameter of the PMMA cylinders is 21 ± 4 nm. These results are about 20% below the estimates obtained from theoretical calculations according to Helfand and Wasserman.
Morphologies of an a) lamellar, and b) hexagonally ordered cylindrical sample (schematic). The triangle in (b) indicates the symmetry that can be used to calculate the dL.magnified imageMorphologies of an a) lamellar, and b) hexagonally ordered cylindrical sample (schematic). The triangle in (b) indicates the symmetry that can be used to calculate the dL.
SAXS from Four‐Arm Polyelectrolyte Stars in Semi‐Dilute Solutions
Authors: Moinard Delphine , Taton Daniel , Gnanou Yves , Rochas Cyrille , Borsali Redouane 
Published: February 2003

AbstractWe have performed small‐angle X‐ray scattering experiments on semi‐dilute solutions of highly charged star polyelectrolytes. Poly(sodium acrylate) (PANa) and poly(cesium acrylate) (PACs) stars with four arms were successfully synthesized by a combination of atom transfer radical polymerization and chemical modifications. Over a wide range of polyelectrolyte concentration Cp, these two systems as well as their equivalent linear polyelectrolytes were investigated at different ionic strengths. Scattering experiments show the existence of a scattering peak denoted as qmax, which disappears with the addition of a simple electrolyte, evidencing the electrostatic character of the interactions. We have also studied the effect of the charge parameter and the nature of the counterion (Na and Cs) on the scattering properties of these star polyelectrolytes. In the case of PACs, qmax scales with the polyelectrolyte concentration as Cp1/2 over the whole range of studied concentrations, whereas it scales as Cp1/2 (for Cp < 45 mg · ml−1) and Cp1/4 (for Cp > 45 mg · ml−1) in the case of PANa.
Variation of qmax as a function of polyelectrolyte concentration Cp for PA1Cs (○) and PA2Cs (•) stars (error bars are indicated).magnified imageVariation of qmax as a function of polyelectrolyte concentration Cp for PA1Cs (○) and PA2Cs (•) stars (error bars are indicated).
Effect of tert‐Butyl Chloride on the Isoprene Polymerization with Neodymium Isopropoxide/Diisobutylaluminum Hydride and Neodymium Isopropoxide/Methylaluminoxane Catalysts
Authors: Dong Weimin , Endo Kiyoshi , Masuda Toshio 
Published: February 2003

AbstractThe effect of tert‐butyl chloride (tBuCl) as a third catalyst component on the isoprene polymerization with neodymium isopropoxide (Nd(OiPr)3)/diisobutylaluminum hydride (Al(iBu)2H) and Nd(OiPr)3/methylaluminoxane(MAO) catalysts was examined in heptane at a fixed [Al]/[Nd] ratio of 30 and reaction temperatures of 30 and 60 °C. The Nd(OiPr)3/Al(iBu)2H catalyst was inactive without tBuCl, i.e., at [Cl]/[Nd] = 0, while it showed the highest activity under the conditions of [Cl]/[Nd] = 3.0 and an addition order of {Al(iBu)2H + tBuCl} + Nd(OiPr)3 to yield polyisoprene with relatively low molecular weight (Mn ca. 5 × 104), broad MWD (Mw/Mn ca. 5.4), and high cis‐1,4 content (ca. 96%) at 30 °C. On the other hand, the Nd(OiPr)3/MAO catalyst was effective at [Cl]/[Nd] = 0, and the most active at [Cl]/[Nd] = 1.0–1.5 with an addition order of {Nd(OiPr)3 + MAO} + tBuCl to afford polymer with high molecular weight (Mn ca. 8 × 105), fairly narrow MWD (Mw/Mn ca. 1.6) and high cis‐1,4 content (ca. 94%) at 30 °C. Thus, the novel Nd(OiPr)3/MAO/tBuCl system features high activity, high molecular weight, narrow MWD, and high cis‐1,4 stereospecificity, as compared with the conventional Nd(OiPr)3/Al(iBu)2H/tBuCl system.
Effect of the [Cl]/[Nd] mole ratio on the cis‐1,4 contents with Nd(OiPr)3/Al(iBu)2H/tBuCl catalyst. Curve a: at 30 °C, 180 min; curve b: at 60 °C, 90 min.magnified imageEffect of the [Cl]/[Nd] mole ratio on the cis‐1,4 contents with Nd(OiPr)3/Al(iBu)2H/tBuCl catalyst. Curve a: at 30 °C, 180 min; curve b: at 60 °C, 90 min.
Crystallization in ABC Triblock Copolymers with Two Different Crystalline End Blocks: Influence of Confinement on Self‐Nucleation Behavior
Authors: Schmalz Holger , Müller Alejandro J. , Abetz Volker 
Published: February 2003

AbstractThe influence of different confinements active during crystallization within polybutadiene‐block‐polyisoprene‐block‐poly(ethylene oxide) (PB‐b‐PI‐b‐PEO) and the corresponding hydrogenated polyethylene‐block‐poly(ethylene‐alt‐propylene)‐block‐poly(ethylene oxide) (PE‐b‐PEP‐b‐PEO) triblock copolymers on the self‐nucleation behavior of the crystallizable PEO and PE blocks is investigated by means of differential scanning calorimetry (DSC). In triblock copolymers with PEO contents ≤ 20 wt.‐% crystallization of PEO is confined within small isolated microdomains (spheres or cylinders), and PEO crystallization takes place exclusively at high supercoolings. Self‐nucleation experiments reveal an anomalous behavior in comparison to the classical self‐nucleation behavior found in semicrystalline homopolymers. In these systems, domain II (exclusive self‐nucleation domain) vanishes, and self‐nucleation can only take place at lower temperatures in domain IIISA, when annealing is already active. The self‐nucleation behavior of the PE blocks is significantly different compared with that of the PEO blocks. Regardless of the low PE content (10–25 wt.‐%) in the investigated PE‐b‐PEP‐b‐PEO triblock copolymers a classical self‐nucleation behavior is observed, i.e., all three self‐nucleation domains, usually present in crystallizable homopolymers, can be located. This is a direct result of the small segmental interaction parameter of the PEP and PE segments in the melt. As a consequence, crystallization of PE occurs without confinement from a homogeneous mixture of PE and PEP segments.
Self‐nucleation regimes of a block copolymer showing confined crystallization by means of DSC.magnified imageSelf‐nucleation regimes of a block copolymer showing confined crystallization by means of DSC.