bluuebunny/crossref_metadata_2025 huggingface dataset:
Multimode fiber lasers based on Bragg gratings and double-clad Yb-doped
fibers
Authors: Kurkov A S , Grukh D A , Medvedkov O I , Paramonov V M , Dianov E M , Yashkov M V , Vechkanov N I , Guryanov A N
Published: August 2004

We have realized a set of multimode lasers based on a
double-clad Yb-doped fiber and Bragg gratings written on a
graded-index multimode fiber. Efficient laser operation in the
spectral range of 1.03-1.09 μm has been observed. Spectral
characteristics of the laser emission have been investigated.
Photodynamic therapy of pigmented melanoma B16 using sterically stabilized
fullerenosomes
Authors: Babincová M , Sourivong P , Leszczynska D , Babinec P
Published: August 2004

Novel multifunctional approach to the therapy of very
virulent pigmented melanoma B16 tumor is proposed based on
exploitation of fullerenosomes, nanostructures build from
sterically stabilized liposomes with incorporated fullerenes
C60 in their lipid bilayers and encapsulated photosensitizer
naphthalocyanate. 24 hours after their intravenous administration
the melanoma tumors implanted in C57 mice were irradiated with one
pulse of 8 ns infrared laser for the bleaching of melanin granules
and for the release of photosensitizer and subsequently
illuminated with 776 nm diode laser for conventional photodynamic
treatment of tumors. Significant tumor response was found which is
markedly larger than that obtained with either treatment alone.
Polypyrrole Thin Films Formed by Admicellar Polymerization Support the Osteogenic Differentiation of Mesenchymal Stem Cells
Authors: Castano Harold , O'Rear Edgar A. , McFetridge Peter S. , Sikavitsas Vassilios I.
Published: August 2004

Summary: The objective of this study was to evaluate the attachment, proliferation, and differentiation of rat mesenchymal stem cells (MSC) toward the osteoblastic phenotype seeded on polypyrrole (PPy) thin films made by admicellar polymerization. Three different concentrations of pyrrole (Py) monomer (20, 35, and 50 × 10−3 M) were used with the PPy films deposited on tissue culture polystyrene dishes (TCP). Regular TCP dishes and PPy polymerized on TCP by chemical polymerization without surfactant using 5 × 10−3 M Py, were used as controls. Rat MSC were seeded on these surfaces and cultured for up to 20 d in osteogenic media. Surface topography was characterized by atomic force microscopy, X‐ray photoelectron spectroscopy, and static contact angle. Cell attachment, proliferation, alkaline phosphatase (ALP) activity, and calcium content were measured to evaluate the ability of MSC to adhere and differentiate on PPy‐coated TCP. Increased monomer concentrations resulted in PPy films of increased thickness and surface roughness. PPy films generated by different monomer concentrations induced drastically different cellular events. A wide spectrum of cell attachment characteristics (from excellent cell attachment to the complete inability to adhere) were obtained by varying the monomer concentration from 20 m to 50 × 10−3 M. In particular the 20 × 10−3 M PPy thin films demonstrated superior induction of MSC osteogenicity, which was comparable to standard TCP dishes, unlike PPy films of similar thickness prepared by chemical polymerization without surfactant.

Adhesion of mesenchymal stem cells on tissue culture plates (TCP) coated with polypyrrole thin films made by admicellar polymerization.

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Adhesion of mesenchymal stem cells on tissue culture plates (TCP) coated with polypyrrole thin films made by admicellar polymerization.
Extracellular Matrix‐Like Surfactant Polymers Containing Arginine‐Glycine‐Aspartic Acid (RGD) Peptides
Authors: Anderson Eric H. , Ruegsegger Mark A. , Murugesan Gurunathan , Kottke‐Marchant Kandice , Marchant Roger E.
Published: August 2004

Summary: We report on a novel series of biomimetic polymers exhibiting interfacial properties similar to the extracellular matrix. A series of well‐defined surfactant polymers were synthesized by simultaneously incorporating arginine‐glycine‐aspartic acid (RGD) peptide, dextran oligosaccharide, and hexyl ligands with controlled feed ratios onto a poly(vinyl amine) (PVAm) backbone. The peptide sequence was H‐GSSSGRGDSPA‐NH2 (Pep) having a hydrophilic extender at the amino terminus and capped carboxy terminus. The peptide‐to‐dextran (Pep:Dex) ratios were varied to create surfactants having 0, 25, 50, 75, and 100 mol‐% peptide relative to dextran. The surfactants were characterized by IR, NMR and atomic force microscopy (AFM) for composition and surface active properties. AFM confirmed full surface coverage of PVAm(Pep)(100%) on graphite, and supported the mechanism of interdigitation of hexyl ligands between surfactant molecules within a specified range of hexyl chain densities. the attachment and growth of human pulmonary artery endothelial cells on the PVAm(Pep)(100%) surface was identical to the fibronectin positive control. Cell adhesion decreased dramatically with decreasing peptide density on the surfactant polymers.

Molecular model of a peptide surfactant polymer, consisting of poly(vinyl amine) backbone with peptide, dextran oligosaccharide and hexyl branches coupled to the polymer chain.

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Molecular model of a peptide surfactant polymer, consisting of poly(vinyl amine) backbone with peptide, dextran oligosaccharide and hexyl branches coupled to the polymer chain.
Fully‐Biodegradable Poly(3‐hydroxybutyrate)/Poly(vinyl alcohol) Blend Films with Compositional Gradient
Authors: Zhao Li , Tsuchiya Katsunori , Inoue Yoshio
Published: August 2004

Summary: Fully‐biodegradable bacterial poly(3‐hydroxybutyrate) (PHB)/chemosynthetic poly(vinyl alcohol) (PVA) blend films with compositional gradient from one surface to the other surface of the films were prepared by a dissolution‐diffusion technique. Three kinds of PVA samples, high‐ and low‐molecular weight atactic PVA and highly syndiotactic PVA (s‐PVA), were used in order to investigate the effects of molecular weight and tactic structure on the generation of compositional gradient. The solution of PHB in 1,1,1,3,3,3‐hexafluoro‐2‐propanol (HFIP), which is also a good solvent for PVA, was cast on the PVA film and then the solvent HFIP was evaporated. By selecting the optimum volume of solvent and the evaporation rate, the PHB/PVA blend film with compositional gradient was obtained. The formation of compositional gradient was confirmed by FT‐IR microscopy and ATR‐FT‐IR analysis. The 50%/50% PHB/s‐PVA blend film with a nearly ideal compositional gradient, that is, the composition of PHB (or PVA) in the film changing gradually from 100% at one surface to 0% at the other surface of the film was obtained by casting PHB/HFIP solution on to the s‐PVA film.

Positional dependence of the absorbance of CO and OH stretching bands along the film thickness direction for the PHB/S‐PVA cast films.

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Positional dependence of the absorbance of CO and OH stretching bands along the film thickness direction for the PHB/S‐PVA cast films.
Bone Tissue Engineering: State of the Art and Future Trends
Authors: Salgado António J. , Coutinho Olga P. , Reis Rui L.
Published: August 2004

Summary: Although several major progresses have been introduced in the field of bone regenerative medicine during the years, current therapies, such as bone grafts, still have many limitations. Moreover, and in spite of the fact that material science technology has resulted in clear improvements in the field of bone substitution medicine, no adequate bone substitute has been developed and hence large bone defects/injuries still represent a major challenge for orthopaedic and reconstructive surgeons. It is in this context that TE has been emerging as a valid approach to the current therapies for bone regeneration/substitution. In contrast to classic biomaterial approach, TE is based on the understanding of tissue formation and regeneration, and aims to induce new functional tissues, rather than just to implant new spare parts. The present review pretends to give an exhaustive overview on all components needed for making bone tissue engineering a successful therapy. It begins by giving the reader a brief background on bone biology, followed by an exhaustive description of all the relevant components on bone TE, going from materials to scaffolds and from cells to tissue engineering strategies, that will lead to “engineered” bone.

Scaffolds processed by using a methodology based on extrusion with blowing agents.

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Scaffolds processed by using a methodology based on extrusion with blowing agents.
Release of Chlorambucil from Poly(N‐isopropylacrylamide) Hydrogels with β‐Cyclodextrin Moieties
Authors: Liu Yu‐Yang , Fan Xiao‐Dong , Hu Hui , Tang Zhong‐Hua
Published: August 2004

Summary: The present work is focused on investigating the behavior of controlled drug release poly(N‐isopropylacrylamide) (PNIPA) hydrogels in the presence of β‐cyclodextrin (β‐CD). For this purpose, three types of NIPA hydrogels with β‐CD moieties were synthesized with different architectures according to our previous studies. An anti‐cancer drug (chlorambucil, CLB), which can form an inclusion complex with β‐CD, was selected for loading and in vitro release studies. The drug was loaded into hydrogels via a swelling method. DSC was used to study the interactions between the CLB molecules and the polymers. The results indicate that the CLB‐polymer interactions are at the molecular level. Loading CLB into these polymers can result in an evident decrease in the glass transition temperature (Tg), and the variation of Tg (ΔTg) depends on the structures of the polymers and their β‐CD content. The controlled release experiments show that the presence of β‐CD can markedly enhance CLB release from shrunken PNIPA hydrogels and increase the ratio of CLB released in total drug loading content.

Release profile of CLB from hydrogels 1a‐c and 4 at pH 1.4 and 7.4, at 37 °C.

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Release profile of CLB from hydrogels 1a‐c and 4 at pH 1.4 and 7.4, at 37 °C.
Enzymatic Synthesis and Chemical Recycling of Poly(carbonate‐urethane)
Authors: Soeda Yasuyuki , Toshima Kazunobu , Matsumura Shuichi
Published: August 2004

Summary: Novel enzymatically recyclable poly(carbonate‐urethane) consisting of a diurethane moiety as a hard segment and a carbonate linkage as an enzymatically cleavable unit was prepared by the polycondensation of biodegradable diurethanediol and diethyl carbonate using lipase. The produced poly(carbonate‐urethane) was readily transformed by lipase into the corresponding cyclic oligomers which were more easily repolymerized by lipase to produce a higher molecular weight poly(carbonate‐urethane) than that of the parent poly(carbonate‐urethane).

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End‐Functionalised 1‐Vinyl‐2‐Pyrrolidinone Oligomers Bearing Lactate Functions at One End
Authors: Ranucci Elisabetta , Macchi Luca , Annunziata Rita , Ferruti Paolo , Chiellini Federica
Published: August 2004

Summary: 1‐Vinyl‐2‐pyrrolidinone (VP) oligomers bearing a lactate group at one end (PVP‐L) were obtained by chain‐transfer controlled radical polymerisation carried out in the presence of ethyl L‐lactate as chain‐transfer agent (CTA). Their number‐average molecular weights were in the range 1500–4000 with molecular weight distributions ranging from 1.4 to 1.8. The chain transfer constant, CT, of the ethyl L‐lactate/VP system was determined by monitoring the variation of PVP‐L number‐average molecular weight on conversion. The CT value so obtained was 1.03 × 10−2, which is by about one order of magnitude higher than the CT value previously determined for a seemingly similar system, namely methyl isobutyrate/1‐vinyl‐2‐pyrrolidinone (1.64 × 10−3). The resultant PVP‐L oligomers were thoroughly characterised by means of 1H and 13C NMR, in order to ascertain the regular presence of the lactate functions at one of their chain terminals. NMR characterisations gave results in full agreement with the proposed structure. Moreover, the molecular weight values determined by NMR very closely agreed with those obtained by SEC. Preliminary biological evaluations of the PVP‐L oligomers showed a complete lack of toxicity.

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Local Chain Mobility of Gellan in Aqueous Systems Studied by Fluorescence Depolarization
Authors: Horinaka Jun‐ichi , Kani Kohei , Honda Haruhiko , Uesaka Yoko , Kawamura Takanobu
Published: August 2004

Summary: The local chain mobility of a gellan, an electrolyte polysaccharide, in aqueous systems was examined with respect to the effect of the temperature, the concentration of gellan (cG), and the concentration of added salt (cS). The relaxation time of local motion was estimated for fluorescein isothiocyanate (FITC)‐labeled‐gellan by the fluorescence depolarization technique, and the chain mobility was discussed. The relaxation time increased with decreasing temperature, in particular when accompanying the coil‐helix transition due to the great difference in chain mobility between the coil and the helical conformations. The effect of cG was observed for gellan solutions even below the critical concentration of chain entanglement (2 wt.‐%) for well‐expanded nonelectrolyte polymers with size similar to that of the gellan. This suggests that the actual excluded volume of gellan is larger than that of nonelectrolyte polymers due to the electrostatic repulsion between segments. The relaxation time for 0.2 wt.‐% systems of gellan in coil conformation is independent of cS, whereas a cS dependence of the relaxation time is clearly observed for 0.5 wt.‐% systems. The degree of expansion of the gellan chain is independent of the shielding effect of cations on the electrostatic repulsion between gellan segments due to the stiffness of gellan chain. On the other hand, the cG as well as the cS dependence of the chain mobility is clearly observed for gellan in the helical conformation, examined over the concentration range, probably due to the partial aggregation of helices induced by the attractive interaction between gellan segments.

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Influence of the mode of introduction of a reactive element on the high temperature oxidation behavior of an alumina‐forming alloy. Part II: Cyclic oxidation tests
Authors: Chevalier S. , Dawah Tankeu A. P. , Buscail H. , Issartel C. , Borchardt G. , Larpin J. P.
Published: August 2004

Several routes of yttrium introduction were applied to test the high temperature oxidation performance of a FeCrAl alloy. Isothermal oxidation tests were described in a previous paper (Part I of this paper in this journal, 2004, 55, 352). Cyclic oxidation tests were performed in air under atmospheric pressure on blank specimens, Y2O3 sol‐gel coated‐, Y2O3 metal‐organic chemical vapor deposited (MOCVD)‐, yttrium ion implanted‐alloys, as well as on a steel containing 0.1 wt. % of yttrium as an alloying element. For the 20 hours cycles, all the samples, except FeCrAl‐0.1Y, exhibit weight losses after a few cycles, indicating drastic spallation of the oxide scales. The MOCVD coated specimen has the highest weight loss. The oxidation kinetics of the FeCrAl‐0.1Y alloy obey a parabolic law, indicating that the alumina scale formed on its surface is protective even after more than 1200 hours of oxidation (> 50 cycles). The 100 hours cycle oxidation tests give similar results. The FeCrAl‐0.1Y alloy exhibits the best oxidation behavior with very little spallation after more than 2000 hours (85 days) of oxidation at 1100°C (20 cycles). Most of the other samples exhibit severe oxide scale spallation followed by an increase of their oxidation rate related to the formation of non‐protective iron oxides.
Effects of turbulent flow on the corrosion kinetics of X52 pipeline steel in aqueous solutions containing H2S
Authors: Galvan‐Martinez R. , Mendoza‐Flores J. , Duran‐Romero R. , Genesca‐Llongueras J.
Published: August 2004

This work presents the electrochemical results obtained during the study of the corrosion of X52 pipeline steel sample, immersed in brines containing H2S, under turbulent flow conditions. Linear polarisation resistance (LPR), electrochemical impedance spectroscopy (EIS), Electrochemical Noise (EN) and polarisation curves were used in order to determine the effect of turbulent flow upon the corrosion kinetics of the steel. It was found that flow has a considerable influence upon the electrochemical process occurring on the surface of the steel and the corrosion rate is increased.
Microstructure and corrosion behaviour of plasma‐nitrocarburized sintered steel
Authors: Borges P. C. , Martinelli A. E. , Franco C. V.
Published: August 2004

Powder characteristics and manufacturing processes determine the microstructure, and therefore, the physical, chemical, and mechanical properties of sintered steels. In particular, porosity and corrosion resistance are intimately related, since the contact area between substrate and electrolyte significantly affects the corrosion resistance of sintered steels. This study addresses the effect of powder characteristics and pressing parameters on the microstructure and corrosion resistance of low‐carbon sintered and sintered/plasma‐nitrocarburized steel. The results indicated that the corrosion resistance increased with increasing density and decreasing specific surface area. Additionally, plasma‐nitrocarburizing was highly effective in coating open pores of the material.
Aromatic Polyethers with a 4‐Chloro‐3‐trifluoromethylphenyl Group
Authors: Liu Baijun , Hu Wei , Jin Yuhui , Chen Chunhai , Jiang Zhenhua , Wu Zhongwen , Matsumoto Toshihiko , Matsumura Akiko
Published: August 2004

Summary: A novel bisphenol, (4‐chloro‐3‐trifluoromethyl)phenylhydroquinone (3FC‐PH), was synthesized via a three‐step synthetic procedure. Four aromatic polyethers based on 3FC‐PH were prepared via a nucleophilic aromatic substitution polycondensation. These polymers had a high thermal stability, and the temperatures at a 5% weight loss were above 516 °C in air. The solubility of the polyethers was improved by the introduction of bulky pendant groups. The average refractive indices of the polymer films at 1 320 nm were in the range 1.5381–1.6145. The dielectric constants of the polyether films estimated from the refractive indices were 2.69–2.98. Highly fluorinated 3FC‐PAE exhibited lower light absorption in the near‐IR region.

Part of the 1H NMR spectra of 3FC‐PAE.

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Part of the 1H NMR spectra of 3FC‐PAE.
Synthesis and Micellization of Star‐Shaped Poly(ethylene glycol)‐block‐Poly(ε‐caprolactone)
Authors: Kim Keon Hyeong , Cui Guo Hua , Lim Hyung Jun , Huh June , Ahn Cheol‐Hee , Jo Won Ho
Published: August 2004

Summary: The relationship between the architecture of block copolymers and their micellar properties was investigated. Diblock, 3‐arm star‐shaped and 4‐arm star‐shaped block copolymers based on poly(ethylene glycol) and poly(ε‐caprolactone) were synthesized. Micelles of star‐shaped block copolymer in an aqueous solution were then prepared by a solvent evaporation method. The critical micelle concentration and the size of the micelles were measured by the steady‐state pyrene fluorescence method and dynamic light scattering, respectively. The CMC decreased in the order di‐, 3‐arm star‐shaped and 4‐arm star‐shaped block copolymer. The size of the micelles increased in the same order as the CMC. Theory also predicts that the formation of micelles becomes easier for 4‐arm star‐shaped block copolymers than for di‐ and 3‐arm star‐shaped block copolymers, which qualitatively agrees with the experiments.

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Effect of Ethanol on the Rheological Properties of Water‐Rich Gels of Diblock Copolymer E43B11
Authors: Kelarakis Antonis , Havredaki Vasiliki , Booth Colin
Published: August 2004

Summary: The effect of added ethanol on the rheological behaviour of aqueous solutions of diblock copolymer E43B11 (E = oxyethylene unit, B = oxybutylene unit) has been investigated. Thermally reversible sol‐gel transitions were observed for concentrated solutions of the copolymer in solutions containing 0–30 wt.‐% ethanol. Storage (G′) and loss (G″) moduli and yield stress (σy) were used to define hard and soft gel phases. The introduction of 10 wt.‐% ethanol did not alter the phase behaviour greatly, whereas higher ethanol concentrations had a large effect, which differed in kind from that reported for triblock copolymers of ethylene oxide and propylene oxide, type EPE.

Temperature dependence of the logarithm of (•) storage and (○) loss modulus for 20 wt.‐% copolymer in 10 wt.‐% ethanol.

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Temperature dependence of the logarithm of (•) storage and (○) loss modulus for 20 wt.‐% copolymer in 10 wt.‐% ethanol.
Cationic Polymerization of 2‐Vinylthiophene by Chloroarylmethanes as Surface Initiators on Silica and Consecutive Hydride Abstraction by Acceptors
Authors: Höhne Susanne , Seifert Andreas , Friedrich Manfred , Holze Rudolf , Spange Stefan
Published: August 2004

Summary: 2‐Vinylthiophene (2‐VT) has been cationically polymerized using chloroarylmethane derivatives as the surface polymerization initiator on silica. By applying this procedure a soluble fraction of poly(vinylthiophene) (PVT) and PVT/silica composites can be simultaneously synthesized. The mass balance of the products (soluble fraction and hybrid particle fraction) depends significantly on temperature and 2‐VT/silica ratio. The hydride abstraction reaction of PVT both in solution and immobilized on silica particle surface has been studied using 2,3‐dichloro‐5,6‐dicyano‐1,4‐quinone (DDQ), tetrachloro‐1,4‐quinone (chloranile = ClA) and triphenylmethylium as reagents. The transformation process of PVT towards conjugated polymers has been studied with UV‐vis spectroscopy and ESR spectroscopy. Cyclic voltammetry shows that chloranil is complexated with the formed polymer. Radical formation increases with increasing degree of conversion. The soluble fraction of the conjugated PVT sections formed is capable of reacting with each other as evidenced by GPC data. Structure of PVT/silica and resulting hybrid materials have been investigated by solid state 13C {1H} CP MAS NMR‐spectroscopy showing a reaction of methine and methylene hydrogen atoms after treatment with DDQ or chloranil as hydride acceptors. For all poly‐(2‐vinylthiophene)/hydride acceptor systems studied, chloranil has been found to be the best reagent for the transformation of PVT towards conjugated polymers.

Transformation of PVT in poly(2‐ethinylthiophene) (PET) and PVT‐PET copolymers.

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Transformation of PVT in poly(2‐ethinylthiophene) (PET) and PVT‐PET copolymers.
Block Copolymers Build‐up of Electron and Hole Transport Materials
Authors: Behl Marc , Zentel Rudolf
Published: August 2004

Summary: In this article we describe the synthesis of various monomers modified with triphenyl‐1,3,5‐triazine side groups as electron transport moieties. By nitroxide‐mediated polymerization with a TEMPO unimer it was possible to obtain polymers with a narrow polydispersity. Furthermore, by living radical polymerization block copolymers were obtained from these monomers. Therefore, microphase separated structures are accessible which possess hole conducting moieties in one phase and electron conducting moieties in the other phase.

General build‐up of the copolymers consisting of hole and electron conductor.

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General build‐up of the copolymers consisting of hole and electron conductor.
Demonstration of the Existence of Long‐Lived Species in the Cationic Polymerization of 1,3‐Pentadiene Initiated by Aluminium Trichloride in Non Polar Solvent
Authors: Bennevault‐Celton Véronique , Delfour Marilyn , Cheradame Hervé
Published: August 2004

Summary: A kinetic study of the polymerization of a mixture of 1,3‐pentadiene isomers initiated by AlCl3 was carried out in pentane at −10 and 20 °C. A second apparent monomer order was found mainly at room temperature and was explained by a complexation of propagating active centers by the polymer, the true monomer order being first. This apparent order did not result from the presence of the two isomers in the monomer mixture. Kinetic simulations confirmed this interpretation and pointed out the fact that the interaction between the polymer and the active centers was stronger at −10 °C, thus limiting the polymer conversion at this temperature. The novelty of these findings lies in the fact that the inactive complexed centers can be activated by reaction with the monomer, providing active species when necessary. The existence of active centers even after a long reaction time at room temperature, and the reactivation of the complexed centers, was evidenced by incremental monomer addition and by the formation of sulfonium ions after quenching the polymerization by an excess of dimethyl sulfide. The latter were characterized by 1H NMR spectroscopy.

Complexation of propagating active centers by the polymer giving dormant species (C+/P), with following reactivation by a new monomer charge.

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Complexation of propagating active centers by the polymer giving dormant species (C+/P), with following reactivation by a new monomer charge.
Effect of Macrocycles on the Temperature‐Responsiveness of Poly[(methoxy diethylene glycol methacrylate)‐graft‐PEG]
Authors: Kitano Hiromi , Hirabayashi Tadashi , Gemmei‐Ide Makoto , Kyogoku Mayumi
Published: August 2004

Summary: A homopolymer of 2‐(2′‐methoxyethoxy)ethyl methacrylate (DM) dissolved in pure water demonstrated an abrupt increase in its turbidity at a critical temperature (LCST). Meanwhile, the LCST for a copolymer of DM and ω‐methoxy(oligoethyleneoxy)ethyl methacrylate (PaM) (PDMPaM) significantly increased with increasing content of PaM residue. Furthermore, the addition of macrocycles such as hexasodium calix[6]arenehexasulfonic acid (SCX6), α‐cyclodextrin (α‐CD) and 2,6‐di‐O‐methyl‐β‐cyclodextrin (DM‐β‐CD) changed the LCST. SCX6 raised the LCST significantly, DM‐β‐CD slightly raised the LCST and α‐CD slightly lowered it. These phenomena could be attributed to the formation of an inclusion complex (polypseudorotaxane) at the grafted PEG chain of the copolymer. ROESY, fluorescence measurements and the viscosity behavior of the SCX6‐PEG dimethylether (PEG‐DME) mixture supported the theory of the complexation of SCX6 with the PEG chain. The apparent association constants (Kapp) of PEG‐DME or grafted PEG with SCX6 and α‐CD were determined using fluorescence and UV‐vis absorption measurements, respectively. The complexation of the SCX6‐polymer conjugate with PDMPaM was also examined by time‐evolution measurements of the turbidity. The effect of the structure of guest and host molecules on the LCST for the copolymer was discussed in detail.

Schematic representation of the formation of polypseudorotaxane of PDMPaM with SCX6.

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Schematic representation of the formation of polypseudorotaxane of PDMPaM with SCX6.
Preparation of Scratch and Abrasion Resistant Polymeric Nanocomposites by Monomer Grafting onto Nanoparticles, 5
Authors: Bauer Frank , Ernst Horst , Hirsch Dietmar , Naumov Sergej , Pelzing Mathias , Sauerland Volker , Mehnert Reiner
Published: August 2004

Summary: Reinforced clear coats were prepared using nanosized silica and alumina particles in UV/EB curable acrylate formulations. For a firm embedding of the oxide nanofillers via covalent bonds to the network acrylates their surfaces were modified by polymerization‐active trialkoxysilanes, e.g., methacryloxypropyltrimethoxysilane and vinyltrimethoxysilane. The cured nanocomposite clear coats showed improved scratch and abrasion resistance. However, oxide modifications accomplished by silanes having polymerization‐inactive methyl, propyl, and isobutyl functionalities yield coatings with similar scratch and abrasion resistance. To explain these findings, infrared and multinuclear MAS NMR experiments, MALDI‐TOF and ESI‐MSn mass spectroscopy, and atomic force microscopy results were used to reveal the structure of surface‐anchored organosilanes and their interaction with the acrylate matrix. Ladder‐like polysiloxane chains chemically grafted onto the filler particles have been proposed. These ladder‐like structures build a short range interpenetrating network with the polyacrylates. This results in a durable link between the organic and inorganic phase.

Proposed ladder‐like arrangement of T3 structure of silicon atoms in MEMO polysiloxanes grafted on silica surface.

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Proposed ladder‐like arrangement of T3 structure of silicon atoms in MEMO polysiloxanes grafted on silica surface.
Effects of Residual Nuclei on Crystals and Equilibrium Melting Points of Dual Crystals in Poly(ethylene 2,6‐naphthalene‐dicarboxylate)
Authors: Woo Eamor , Huang Doan‐Ho , Wu Ming‐Chien
Published: August 2004

Summary: The crystal structures and possible transformations in poly(ethylene naphthalate) (PEN) were examined using differential scanning calorimetry (DSC) and wide‐angle X‐ray diffraction (WAXD). The crystal cells (α‐ and β‐form) were dependent on several factors related to their thermal histories. For PEN subjected to Tmax = 280 °C (where Tmax is the maximum melt temperature at which the samples were treated before crystallization), only the α‐form developed regardless of the temperature of crystallization or cooling rate. However, for PEN subjected to Tmax = 300 °C, PEN developed mixed dual crystals, with greater fractions of the α‐form at low temperatures of crystallization (220 °C or lower) or higher cooling rates, but higher β‐form fractions at higher crystallization temperatures (>230 °C). The difference in the relative stability of these two crystals was utilized to prepare PEN containing only the α‐form or only the β‐form. The equilibrium melting temperatures of these two crystal forms in PEN were then measured separately. For PEN containing only the β‐form, T (289.3 °C) was found by using the Hoffman‐Weeks technique, while for PEN containing only the α‐form, T was determined using the same technique but was found to be lower (282.6 °C).

Comparison of Hoffman‐Weeks extrapolations for the α‐crystal and β‐crystal, respectively, in PEN.

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Comparison of Hoffman‐Weeks extrapolations for the α‐crystal and β‐crystal, respectively, in PEN.
Unexpected Formation of Atactic Blocks in Propylene/1‐Pentene Copolymers from rac‐Me2Si(2‐MeBenz[e]Ind)2ZrCl2
Authors: Sacchi Maria Carmela , Forlini Fabrizio , Tritto Incoronata , Stagnaro Paola
Published: August 2004

Summary: Supplementary experimental findings are reported in addition to those presented in a previous paper dealing with the microstructure of propylene/1‐pentene copolymers prepared with rac‐Me2Si(2‐MeBenz[e]Ind)2ZrCl2. The fractionation results which demonstrate that the atactic part of the copolymer can not be separated from the isotactic one confute the hypothesis suggested by other authors according to which the catalyst used could contain a percent of impurities of the meso (aspecific) form. This evidence is in agreement with the observed narrow polydispersities and the almost random distribution of the comonomers (rP · rCm ≈ 1) which are typical of single site catalysts.

13C NMR methyl region of pentane‐soluble (a) and pentane‐insoluble (b) fractions of copolymer prepared with MBI.

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13C NMR methyl region of pentane‐soluble (a) and pentane‐insoluble (b) fractions of copolymer prepared with MBI.
Cover Picture: Macromol. Chem. Phys. 12/2004
Authors: Woo Eamor , Huang Doan‐Ho , Wu Ming‐Chien
Published: August 2004

Back Cover: The Figure on the cover shows a comparison of Hoffman‐Weeks extrapolations for poly(ethylene 2,6‐naphthalene‐dicarboxylate) (PEN) specimens containing only α‐crystal and β‐crystal, respectively. The insets show x‐ray diffraction patterns of PEN melt crystallized in two steps with different maximum melt temperatures before crystallization. The thermal history is an important factor which influences the formation of the crystal cells.

Further details can be found in the Full Paper by E.‐M. Woo,* D.‐H. Huang, and M.‐C. Wu on page 1644.
Synthesis and Characterization of New Aromatic Polyamides with N,N′‐Di(4‐n‐alkylphenyl)benzodiimide Unit on the Main Chain
Authors: Choi Kyung Ho , Jung Jin Chul
Published: August 2004

Summary: New aromatic polyamides containing two n‐alkylphenylimide units fused to the main chain were prepared by the activated polyamidation of 3,6‐di(4‐carboxyphenyl)‐N,N′‐di(4‐n‐alkylphenyl)pyromellitimides (CmDA, m = 0, 8, 12, 16) with oxy‐4,4′‐dianiline in a mixture of N‐methylpyrrolidone and pyridine (Py) in the presence of triphenyl phosphite and CaCl2. The imide‐containing dicarboxylic acid monomers were synthesized by the imidization of 3,6‐di(4‐carboxyphenyl)pyromellitic dianhydride with 4‐n‐alkylanilines. The polymers showed both enhanced thermal stability and excellent solubility due to the presence of thermally stable pendent imido groups and internally plasticizing n‐alkyl chains. Their glass transition temperatures were between 225 and 285 °C and decreased with increasing side chain length. Wide‐angle X‐ray diffraction investigations revealed that all the polymers are amorphous and have typical layered structures formed by n‐alkyl side chains.

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Structure and Properties of Compatible PPSF‐Rich Blends with PET
Authors: Retolaza Aritz , Eguiazábal José I. , Nazábal Jon
Published: August 2004

Summary: New PPSF/PET (poly(phenyl sulfone)/poly(ethylene terephthalate)) blends rich in PPSF were obtained by direct injection molding. Biphasic morphologies with a very large interface area/dispersed phase volume ratio were obtained and were attributed to a low interfacial tension in the melt state, a consequence of the reactions observed between the components of the blends. This favorable morphology led to small strain mechanical properties close or slightly above those predicted by the direct rule of mixtures, and more significantly, to elongations at break of the blends higher than that of the PPSF matrix.

Morphology of the cryogenically‐broken etched surface of a PPSF/PET 75/25 blend.

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Morphology of the cryogenically‐broken etched surface of a PPSF/PET 75/25 blend.
On Toughness and Stiffness of Poly(butylene terephthalate) with Epoxide‐Containing Elastomer by Reactive Extrusion
Authors: Yu Zhong‐Zhen , Yan Cheng , Dasari Aravind , Dai Shaocong , Mai Yiu‐Wing , Yang Mingshu
Published: August 2004

Summary: To obtain a balance between toughness (as measured by notched impact strength) and elastic stiffness of poly(butylene terephthalate) (PBT), a small amount of tetra‐functional epoxy monomer was incorporated into PBT/[ethylene/methyl acrylate/glycidyl methacrylate terpolymer (E‐MA‐GMA)] blends during the reactive extrusion process. The effectiveness of toughening by E‐MA‐GMA and the effect of the epoxy monomer were investigated. It was found that E‐MA‐GMA was finely dispersed in PBT matrix, whose toughness was significantly enhanced, but the stiffness decreased linearly, with increasing E‐MA‐GMA content. Addition of 0.2 phr epoxy monomer was noted to further improve the dispersion of E‐MA‐GMA particles by increasing the viscosity of the PBT matrix. While use of epoxy monomer had little influence on the notched impact strength of the blends, there was a distinct increase in the elastic stiffness. SEM micrographs of impact‐fracture surfaces indicated that extensive matrix shear yielding was the main impact energy dissipation mechanism in both types of blends, with or without epoxy monomer, and containing 20 wt.‐% or more elastomer.

SEM micrographs of freeze‐fractured surfaces of PBT/E‐MA‐GMA blend illustrating the finer dispersion of E‐MA‐GMA in the presence of epoxy monomer.

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SEM micrographs of freeze‐fractured surfaces of PBT/E‐MA‐GMA blend illustrating the finer dispersion of E‐MA‐GMA in the presence of epoxy monomer.
Compatibilization of Poly(propylene)/Polyamide 6 Blends with Functionalized Poly(propylene)s Prepared with Metallocene Catalyst
Authors: Hippi Ulla , Korhonen Maija , Paavola Santeri , Seppälä Jukka
Published: August 2004

Summary: Propylene was copolymerized with 10‐undecen‐1‐ol using dimethylsilanylbis(2‐methyl‐4‐phenyl‐1‐indenyl)zirconium dichloride as catalyst and MAO and TIBA as cocatalysts. Comonomer incorporations from 0.1 to 0.9 mol‐% (0.5 to 3.6 wt.‐%) were obtained. These hydroxyl functionalized copolymers were applied as compatibilizers to PP/PA6 blend with a composition of 70/30. For comparison, hydroxyl functionalized polyethylene prepared with metallocene catalyst and commercial MAH grafted ethylene butyl acrylate (E/BA/MAH) and poly(propylene) (PP‐g‐MAH) were also used as compatibilizers. Effects of the compatibilizers on morphology and mechanical and thermal properties of the blends were studied. Enhanced adhesion between the blend components was observed in morphology and dynamic mechanical studies. Although improvement in toughness was not as pronounced as expected, there were indications that the hydroxyl functionalized propylene copolymers prepared with metallocene catalysts could serve as a new type of compatibilizer in polymer blends.

SEM micrograph (5 000×) of an PP/PA6/PP‐co‐OH4 blend.

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SEM micrograph (5 000×) of an PP/PA6/PP‐co‐OH4 blend.
A Novel Phosphorus‐Containing Polymer as a Highly Effective Flame Retardant
Authors: Chang Yu‐Long , Wang Yu‐Zhong , Ban Da‐Ming , Yang Bing , Zhao Guo‐Ming
Published: August 2004

Summary: A novel phosphorus‐containing polymeric retardant, WLA‐3, was synthesized from phenylphosphonic dichloride (PPD) and 2‐(6‐oxido‐6H‐dibenz〈c,e〉〈1,2〉oxaphosphorin‐6‐yl) 1, 4‐benzenediol (ODOPB). The flame‐retardant element, phosphorus, was bonded both in the main chains and in the pendant chains of flame‐retardant polymer molecules, and reached a content of 13.8%. The high phosphorus content and rich aryl group structures of WLA‐3 contribute an excellent flame retardancy to poly(ethylene terephthalate) (PET) without a considerable decrease of mechanical properties. WLA‐3 is also very effective in improving flame retardancy of epoxy resin and unsaturated polyester.

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Reaction Calorimetry in Supercritical Carbon Dioxide
Authors: Fortini Sophie , Lavanchy Frédéric , Meyer Thierry
Published: August 2004

Summary: Reaction calorimetry is an efficient tool used to obtain kinetic, thermodynamic and safety data. A reaction calorimeter, RC1e‐HP350, developed in collaboration with Mettler‐Toledo GmbH, allows investigating chemical reactions under supercritical conditions. The main technical difference, compared with a classical liquid system, is that the whole reactor volume is occupied by the media. Heat transfer analysis in supercritical carbon dioxide (scCO2) by the Wilson plot method shows that the behavior of the internal heat transfer coefficient in scCO2 is the opposite of the one observed for classical liquid. In scCO2 the lower the temperature (above the critical point) the better the internal heat transfer coefficient. The evolution of scCO2 thermodynamical and transport properties near the critical point are responsible for this behavior. The dispersion polymerization of methyl methacrylate in scCO2, with the polydimethylsiloxane monomethacrylate as stabilizer, is used as a model reaction. A polymerization reaction enthalpy of −56.9 ± 2.2 kJ · mol−1 is determined, being in good agreement with previously reported data. The results presented illustrate the accuracy of the heat balance model used and emphasize the potential of reaction calorimetry for the promotion of supercritical fluids technologies.

Technical comparison between liquid and supercritical reaction calorimetry.

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Technical comparison between liquid and supercritical reaction calorimetry.
Fluorinated Hyperbranched Polymers as Additives in Cationic Photopolymerization
Authors: Sangermano Marco , Malucelli Giulio , Bongiovanni Roberta , Vescovo Lorenzo , Priola Aldo , Thomas Richard R. , Kim Yongsin , Kausch Charles M.
Published: August 2004

Summary: Different fluorinated hyperbranched polymers (HBP) were synthesized starting from fluorinated oxetanes and employed as additives in cationic photopolymerization of epoxy monomers. As previously observed for other hydroxyl containing HBP, they interact with the polymeric carbocation through a chain transfer mechanism inducing an increase in the final epoxy conversion. High gel content values (>96%) for the photocured films confirm that the HBP additive is tightly crosslinked to the polymeric network. In the presence of this fluorine‐containing HBP it is possible to influence the bulk properties, as well as, the surface properties. The fluorinated HBP tends to migrate to the surface inducing an increase of hydrophobicity.

The hyperbranched polymer used in this work.

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The hyperbranched polymer used in this work.
Preparation of Poly(3,4‐ethylenedioxythiophene) in a Chiral Nematic Liquid‐Crystal Field
Authors: Goto Hiromasa , Akagi Kazuo
Published: August 2004

Summary: The 3,4‐ethylenedioxythiophene (EDOT) monomer in a chiral nematic liquid‐crystal electrolyte was polymerized by application of a voltage to yield a thin film. Circular dichroism measurements indicated a Cotton effect for the film. Optical texture suggests that the polymer shows a finger‐print texture and a spiral texture similar to that of the chiral nematic phase. This simple method provides a new technique for preparing chiral conducting films in a thermotropic chiral liquid‐crystal field.

Optical micrograph of (R)‐PEDOT* (no polarizer).

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Optical micrograph of (R)‐PEDOT* (no polarizer).
Stability of Nanoporous Materials
Authors: Muralidharan Vijayanand , Hui Chung‐Yuen
Published: August 2004

Summary: The stability of nanoporous materials as a result of surface interaction forces has been considered in this paper. We show that cylindrical pores in linear elastic materials will collapse if α = γ/μA > 2. As one would expect physically, smaller cavities tend to be more unstable for the same surface energy and material properties as a result of the high internal Laplace pressure. Extensions to account for large deformation and strain‐hardening effects and for viscoelastic materials are discussed.

Normalized potential energy versus cavity stretch for the well‐known Neo–Hookean material model. The equilibrium solution shifts to the left as the parameter α increases, implying a greater cavity shrinkage.

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Normalized potential energy versus cavity stretch for the well‐known Neo–Hookean material model. The equilibrium solution shifts to the left as the parameter α increases, implying a greater cavity shrinkage.
Modular Synthesis of Functional Block Copolymers
Authors: Justynska Justyna , Schlaad Helmut
Published: August 2004

Summary: The free‐radical addition of ω‐functional mercaptans to the vinyl double bonds of 1,2‐polybutadiene‐block‐poly(ethylene oxide) copolymers was used for modular synthesis of well‐defined functional block copolymers. The modification reaction proceeds smoothly and yields quantitatively functionalized block copolymers (1H NMR and FT‐IR spectroscopy) without disturbing the molecular‐weight distribution of the parent copolymer (PDI < 1.09, size exclusion chromatography).

The modular synthetic pathway towards the functional block copolymers reported here.

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The modular synthetic pathway towards the functional block copolymers reported here.
Metoclopramide‐induced tardive dyskinesia in an infant
Authors: Mejia Nicte I. , Jankovic Joseph
Published: August 2004

We describe a 1‐year‐old girl who developed orofaciolingual stereotypy at age 2 months after a 17‐day treatment with metoclopramide for gastroesophageal reflux. The stereotypy, documented by sequential videos, persisted for at least 9 months after the drug was discontinued. This patient represents the first documented case of tardive dyskinesia in an infant. We also review previous reports of tardive dyskinesia in children. © 2004 Movement Disorder Society
Rebound psychosis: Effect of discontinuation of antipsychotics in Parkinson's disease
Authors: Fernandez Hubert H. , Trieschmann Martha E. , Okun Michael S.
Published: August 2004

To determine whether psychiatrically stable patients with a history of drug‐induced psychosis could be successfully weaned off their antipsychotic drug, we offered consecutive Parkinson disease (PD) patients on quetiapine or clozapine, who were free of any on‐going psychosis, to be slowly weaned off their antipsychotic drug. Before the study was aborted 6 PD patients (mean age, 78 years) with an average antipsychotic exposure of 20 months (5 on quetiapine, 1 on clozapine) were enrolled. After the antipsychotic agent was discontinued, psychosis recurred in 5 of 6 patients. In 3 patients the “rebound psychosis” was worse than the original psychotic episode and required subsequent higher antipsychotic medication doses. © 2004 Movement Disorder Society
Effects of levodopa and COMT inhibitors on plasma homocysteine in Parkinson's disease patients
Authors: Lamberti Paolo , Zoccolella Stefano , Iliceto Giovanni , Armenise Elio , Fraddosio Angela , De Mari Michele , Livrea Paolo
Published: August 2004

Homocysteine (Hcy) is a risk factor for vascular diseases, cognitive impairment, and dementia. Elevated plasma concentrations of Hcy have been found recently in Parkinson's disease (PD) patients treated with levodopa, suggesting that levodopa is a cause of hyperhomocysteinemia (HHcy). The mechanism underlying HHcy in PD is the O‐methylation of levodopa catalyzed by catechol‐O‐methyltransferase (COMT) that produces S‐adenosylhomocysteine, which is hydrolyzed rapidly to Hcy. COMT inhibitors (COMT‐I) are used currently in the treatment of PD; however, no study has assessed the effects of COMT‐I administration on Hcy concentrations in PD patients. We compared plasma levels of Hcy, B12, and folate in 26 PD patients treated with levodopa, 20 PD patients treated with levodopa + COMT‐I, and 32 controls. No significant differences were found in vitamin B12 levels, whereas folate concentrations were significantly lower in the levodopa‐treated group. Plasma Hcy was increased significantly in the two groups of PD patients and was significantly lower in the group treated with levodopa + COMT‐I. Statistical analysis showed that the difference in mean Hcy levels observed among PD patients was related to the addition of COMT‐I, rather than to folate concentrations. We conclude that levodopa treatment increases plasma Hcy and the addition of COMT‐I effectively reduces HHcy. © 2004 Movement Disorder Society
Paroxysmal non‐kinesigenic dyskinesia in antiphospholipid syndrome
Authors: Engelen Marc , Tijssen Marina A.J.
Published: August 2004

We report on a patient with a mixed movement disorder classifiable as a paroxysmal nonkinesigenic dyskinesia, occurring as the first manifestation of primary antiphospholipid syndrome (PAPS). Possible pathophysiology is discussed based on recent literature, and we stress that PAPS must be considered in movement disorders of a paroxysmal nature. © 2004 Movement Disorder Society
Isolated tongue tremor after gamma knife radiosurgery for acoustic schwannoma
Authors: Chung Sun J. , Im Joo‐Hyuk , Lee Jae‐Hong , Cho A‐Hyun , Kwon Miseon , Lee Myoung C.
Published: August 2004

We describe a patient who had an isolated tongue tremor with an audible click after gamma knife radiosurgery for acoustic schwannoma. The nature of the tongue tremor was clearly demonstrated by videofluoroscopy. The possible pathogenic mechanisms are discussed. © 2004 Movement Disorder Society
A doubly critical degenerate parabolic problem
Authors: Winkler Michael
Published: August 2004

It is shown that the Dirichlet problem for

where Ω⊂ℝn is critical in that it has first eigenvalue one, is globally solvable for any continuous positive initial datum vanishing at ∂Ω. Moreover, for p<3 all solutions are bounded and tend to some nonnegative eigenfunction of the Laplacian as t→∞, while if p⩾3 then there are both bounded and unbounded solutions. Finally, it is shown that unlike the case p∈[0,1), all steady states are unstable if p⩾1. Copyright © 2004 John Wiley & Sons, Ltd.
Existence and uniform decay for Euler–Bernoulli beam equation with memory term
Authors: Park Jong Yeoul , Kim Joung Ae
Published: August 2004

In this article we prove the existence of the solution to the mixed problem for Euler–Bernoulli beam equation with memory term. The existence is proved by means of the Faedo–Galerkin method and the exponential decay is obtained by making use of the multiplier technique combined with integral inequalities due to Komornik. Copyright © 2004 John Wiley & Sons, Ltd.