bluuebunny/crossref_metadata_2025_split huggingface dataset:
Early detection of core deficits in autism
Authors: Sigman Marian , Dijamco Angeline , Gratier Maya , Rozga Agata 
Published: January 2005

AbstractThe goal of this review of the research literature is to discuss approaches to the early detection of autism in infancy. Early detection would enable diagnoses to be made before 18 months of age rather than at 24–30 months, the age where diagnoses start to be made now. After summarizing the criteria for a deficit to be considered “core” to the disorder, the literature on research strategies used in early detection is examined. In order to guide the design of future studies, the review then turns to an overview of what is known about the processes of early social development in typically developing children that underlie the domains in which core deficits are manifested in young children with autism. The social domains covered in the review are those that show development in typically developing infants below 18 months of age: dyadic interaction and imitation; emotion discrimination; and attachment. The review concludes that all of these areas are worthy of investigation in young children, particularly those at higher risk of showing some of the core deficits of autism such as the infant siblings of children with autism. © 2004 Wiley‐Liss, Inc. MRDD Research Reviews 2004;10:221–233.
Synthesis and characterization of novel rigid two‐photon absorbing polymers
Authors: Belfield Kevin D. , Yao Sheng , Morales Alma R. , Hales Joel M. , Hagan David J. , Van Stryland Eric W. , Chapela Victor M. , Percino Judith 
Published: January 2005

AbstractTwo‐photon absorbing polymers with alternating fluorenyl units as a π‐conjugated bridge and bisbenzothiazole or thiazolothiazole as electron‐acceptors were synthesized and characterized by IR, elemental analysis, absorption and fluorescence spectroscopy, and thermogravimetric analysis (TGA). Improvement on the solubility was observed in comparison with their phenyl based analogies. The linear absorption and emission spectra were recorded and high fluorescence quantum yields were found. Relatively large two‐photon absorption cross‐section per repeat unit (420 GM) were measured under fs‐pulsed laser excitation. Copyright © 2005 John Wiley & Sons, Ltd.
Preparation of nano‐sized UV‐absorbing titanium‐oxo‐clusters via a photo‐curing ceramer process
Authors: Soucek Mark D. , Johnson Aaron H. , Meemken Leon E. , Wegner Jonathan M. 
Published: January 2005

AbstractA titanium sol‐gel precursor, titanium (IV) isopropoxide (TIP), was mixed with an epoxidized linseed oil (ELO). Using a cationic super‐acid photoinitiator, triarylsulfonium hexafluoroantimonate, both the organic phase (ELO) and the inorganic phase (TIP) were concomitantly cured. The exposure to moisture was strictly controlled before and during the UV‐curing process. The UV‐Visible spectra, SAXs (small angle X‐ray), DMA (dynamic mechanical properties), and contact angle were investigated as a function of sol‐gel precursor. The UV‐Visible spectra revealed that the inorganic/organic hybrid materials were more effective at blocking the UV‐light than nanoparticulate titanium dioxide while maintaining complete transparency in the visible region. The contact angle data indicated that the inorganic phase preferentially was concentrated at the film‐surface interface. The SAXs data was indicative of a 2‐‐5 nm titanium‐oxo‐cluster size, and the DMA data suggests a well distributed system. Copyright © 2005 John Wiley & Sons, Ltd.
Electrical properties of poly(2‐vinyl pyridine)/silica nanocomposites prepared with perhydropolysilazane
Authors: Saito Reiko , Tobe Tadakuni 
Published: January 2005

AbstractOrganic/silica nanocomposites were prepared by casting the blend solution of organic polymer, poly(2‐vinly pyridine‐co‐methyl methacrylate‐co‐2‐hydroxyethyl methacrylate) or poly(2‐vinly pyridine‐co‐2‐hydroxyethyl methacrylate), and perhydropolysilazane and/or cobalt acetate. Electrical properties of the organic polymer and the composites were measured. Hybridization with perhydropolysilazane and/or cobalt acetate drastically reduced leakage current of the polymer film at 1 MV/cm from 1 × 10−7 to 1 × 10−9 A/cm2 without changing refractive index, dielectric constant and filed breakdown. Nanostructures and thermal stability of the composites were investigated. Copyright © 2005 John Wiley & Sons, Ltd.
Controlled synthesis of silicon‐containing polymers by metal catalysts
Authors: Kawakami Yusuke , Park Sung Young , Uenishi Kazuya , Oishi Motoi , Imae Ichiro 
Published: January 2005

AbstractSilicon‐containing polymers with definite chemical structure were synthesized by reaction of silanes with compounds having multiple bonds (polyaddition) and with water (polycondensation), and by ring‐opening reactions of silacyclobutane or butene derivatives (ring‐opening polymerization). Various optically pure organosilicon compounds were synthesized or separated by HPLC, and stereoregular polycarbosilanes, polycarbosiloxanes and polysiloxanes were synthesized from these compounds used as monomers. Stereochemistry of the elementary reactions producing stereoregular polymers was elucidated. Copyright © 2003 Society of Chemical Industry
The synthesis of functional star copolymers as an illustration of the importance of controlling polymer structures in the design of new materials
Authors: Matyjaszewski Krzysztof 
Published: January 2005

AbstractSeveral different methods for the synthesis of star copolymers employing atom transfer radical polymerization are presented. They include core‐first and arm‐first methods, and a combination of both to prepare mikto‐arm stars. Stars with a well‐defined number of arms were prepared by using a core with a precise number of functional groups, and ill‐defined stars were prepared from hyperbranched cores. In addition, end‐functional stars were prepared by either displacing end‐functional halogens or through radical addition with unreactive functional alkenes. Another approach to end‐functional stars employs functional initiators and the subsequent coupling of the end‐functional arms with difunctional vinyl monomers. Star‐like backbones were also used to grow star‐like macromolecular brushes that were visualized by AFM. The polydispersities of individual arms and entire stars followed Schulz–Flory statistics. Copyright © 2003 Society of Chemical Industry
Electroactive macromonomers based on pyrrole and thiophene: a versatile route to conducting block and graft polymers
Authors: Yagci Yusuf , Toppare Levent 
Published: January 2005

AbstractThe synthesis of block and graft copolymers containing insulating and conducting polypyrrole or polythiophene segments via a two‐step procedure is described. Synthetic pathways to prepare pyrrole and thiophene functional macromonomers involving conventional and controlled/living polymerizations such as anionic and cationic ring opening, atom transfer radical polymerization are discussed. The use of these macromonomers in subsequent electrochemical and chemical polymerizations, leading to the formation of copolymers, is presented. Copyright © 2003 Society of Chemical Industry
Synthesis of polymeric topological isomers through electrostatic self‐assembly and covalent fixation with telechelic poly(THF) having cyclic ammonium salt groups
Authors: Tezuka Yasuyuki , Tsuchitani Akiko , Oike Hideaki 
Published: January 2005

AbstractA pair of macromolecular constitutional isomers having topologically distinctive constructions, ie θ‐shaped and manacle‐shaped polymers, has been synthesized through covalent conversion of an electrostatic polymer self‐assembly comprised of bifunctional linear poly(tetrahydrofuran) [poly(THF)] having N‐phenylpyrrolidinium salt end groups carrying tricarboxylate counteranions (1) under various dilutions. The presence of the two constitutional polymeric isomers was revealed by means of a reverse‐phase liquid chromatography (RPLC) technique. Moreover, size‐exclusion chromatography (SEC) confirmed that one major component possesses notably larger hydrodynamic volume than another, and is assigned as a manacle‐shaped isomer while a minor component as a θ‐shaped isomer. Further details of this unique process were investigated by RPLC analysis of topological isomer products obtained from a series of poly(THF) precursors, 1, having different molecular weights. Copyright © 2003 Society of Chemical Industry
New approach for the synthesis of amino‐containing linear polymers
Authors: Van De Velde Peggy , Goethals Eric J , Du Prez Filip 
Published: January 2005

AbstractA new approach for the synthesis of well‐defined poly(aminoethyl vinyl ether)s with controllable molecular weight has been developed. In a first step poly(chloroethyl vinyl ether)s with narrow molecular weight were prepared via living cationic polymerization of chloroethyl vinyl ether with 1,1‐diethoxyethane/trimethylsilyl iodide/zinc iodide as initiating system. The chloro groups of the resulting polymers were subsequently substituted into phthalimide groups, resulting in the formation of poly(phthalimide ethyl vinyl ether). Hydrazinolysis of the imide functions gave rise to the desired poly(aminoethyl vinyl ether)s. The polymers were characterized by 1H NMR, size exclusion chromatography and X‐ray spectroscopy. The resulting polyamine was soluble only in water and in methanol and showed polyelectrolyte behaviour, as revealed by viscosimetry studies. Copyright © 2003 Society of Chemical Industry
Energy transfer in polystyrene containing pendant stilbene chromophores
Authors: Wuyts Cindy , Dermaut Wim , Hoefnagels Roel , Aerts Gert , Goovaerts Etienne , Geise Herman J 
Published: January 2005

AbstractFour different styrene copolymers with stilbenoid side chains were synthesised under Williamson ether or Wadsworth–Emmons conditions. Blends of these graft copolymers with 4,4′‐bis[2,2‐bis(4‐methoxyphenyl)ethenyl]biphenyl (TMBiPPT), a good blue light emitting oligomer, yielded efficient host–guest systems with only emission from the oligomer. TMBiPPT has a maximum absorption at 365 nm, and the emission spectra of the synthesised graft copolymers all had a significant spectral overlap with the absorption spectrum of TMBiPPT. Since we can tune both the structures of the graft copolymer and the oligomer, this is very promising for obtaining new materials to use in a single‐layer OLED (organic light emitting diode). Copyright © 2003 Society of Chemical Industry
Synthesis and characterisation of water‐soluble poly(ethylene glycol) modified polymethacrylates with the ability to crosslink
Authors: Snellings Geert , Mondelaers Wim , Schacht Etienne 
Published: January 2005

AbstractHydrogels have become increasingly important in the biomedical field. The aim of this study was to develop amphiphilic poly(ethylene glycol) grafted polymethacrylates with curable side groups. The water‐soluble polymers were synthesised by free‐radical copolymerisation of methyl methacrylate, α‐methyl‐ω‐methacroyl‐poly(ethylene glycol) and 2‐hydroxyethyl methacrylate (HEMA). The methacrylate containing hydrogel precursors were obtained by reacting the free hydroxyl groups of HEMA in the polymer with methacrylic anhydride in the presence of catalyst. γ‐Irradiation has been used as an elegant method for crosslinking and simultaneous sterilisation. The influence of the irradiation dose (5, 15, 25 kGy) on the polymers was examined by the determination of the gel and sol fraction. In an aqueous environment these materials behave as hydrogels with more swelling at lower temperatures. Since the coatings can be applied in mild conditions, eg water, these materials are looking very promising as thin film coatings for biomedical applications. Copyright © 2003 Society of Chemical Industry
Micropatterning polyurethane surfaces with lasers
Authors: Martelé Yves , Naessens Kris , Van Daele Peter , Baets Roel , Callewaert Kristof , Schacht Etienne 
Published: January 2005

AbstractThe ablation properties of a series of segmented polyurethanes were investigated after irradiation with excimer lasers (ArF and KrF). The building blocks of the polymers were varied to make a correlation between the chemical structure and the ablation properties (absorption coefficient and threshold value). The aromatic compounds in the segmented polyurethanes were responsible for the KrF excimer laser ablation sensitivity. Polymers with aromatic diisocyanates had the highest absorption coefficient and lowest threshold value. The polymers with only aliphatic compounds could be classified as low absorbing polymers though, the use of ArF excimer laser with aliphatic polymers led to ablation, with formation of well‐defined cavities. In conclusion, the segmented polyurethanes were more sensitive to ArF excimer laser ablation. Copyright © 2003 Society of Chemical Industry
Synthesis of poly(spiroacetal–ether)s
Authors: Maślińska‐Solich Jolanta , Kukowka Sylwia 
Published: January 2005

AbstractPoly(spiroacetal–ether)s were prepared by two alternative synthetic paths (alkaline and acid‐catalysed conditions). Polycondensation of 3,9‐di‐(2‐hydroxyphenyl)‐2,4,8,10‐tetraoxaspiro[5,5]undecane and 1,4‐dibromobutane was performed in solvents (n‐butyl acetate, N,N‐dimethylformamide, dimethyl/sulfoxide) catalysed by K2CO3 or KOH/PTC systems. A similar polymer was formed in the reaction of 2,2‐dihydroxymethyl‐1,3‐propanediol with 1,4 bis(2‐formylphenoxy)butane, catalysed by p‐toluenesulfonic acid. The molecular weight was determined by gel‐permeation chromatography. 1H and 13C NMR were used to study the details of the polymer structure. Copyright © 2003 Society of Chemical Industry
Alternating poly(ester amide)s from succinic anhydride and α,ω‐amino alcohols: synthesis and thermal characterization
Authors: Fey Thomas , Hölscher Markus , Keul Helmut , Höcker Hartwig 
Published: January 2005

AbstractAlternating poly(ester amide)s 6a–e from succinic anhydride and α,ω‐amino alcohols H2N—(CH2)x—OH (x = 2–6) 2a–e were obtained in two steps: α‐carboxyl‐ω‐hydroxy amides 3a–e were prepared from the starting materials in a highly selective reaction, followed by a polycondensation reaction. 1H and 13C NMR analyses of the poly(ester amide)s clearly reveal the alternating microstructure. The poly(ester amide)s with homologous α,ω‐amino alcohols H2N—(CH2)x—OH (x = 2–6) are semi‐crystalline materials, their melting points show the odd/even effect observed for [n]‐polyamides and [n]‐polyurethanes. Heating the poly(ester amide)s 6a–e yields the corresponding N‐(hydroxyalkyl) imides 4a–e with no trace of cyclic ester amides. Theoretical calculations revealed that the cyclic ester amides 5a–e are clearly richer in energy than the isomeric N‐(hydroxyalkyl) imides. These results show that cyclic ester amides can not be prepared from N‐(hydroxyalkyl) imides by ring‐enlargement reactions. Copyright © 2003 Society of Chemical Industry
Preparation of linear low‐density polyethylene by the in situ copolymerization of ethylene with an iron oligomerization catalyst and rac‐ethylene bis(indenyl) zirconium (IV) dichloride
Authors: Zhang Zhicheng , Cui Nannan , Lu Yingying , Ke Yucai , Hu Youliang 
Published: January 2005

AbstractAn iron oligomerization catalyst, [(2‐ArNC(Me))2C5H3N]FeCl2 [Ar = 2,6‐C6H3(F)2], was combined with rac‐ethylene bis(indenyl)zirconium (IV) dichloride [rac‐Et(Ind)2ZrCl2] to prepare linear low‐density polyethylene (LLDPE) by the in situ copolymerization of ethylene. A series of LLDPEs with different properties were prepared by the alteration of the reaction temperature, Fe/Zr molar ratio, Al/(Fe + Zr) molar ratio, and reaction time. The structures of the polymers were characterized with differential scanning calorimetry, 13C NMR, gel permeation chromatography (GPC), and so forth. The melting points, crystallizations, and densities of the resulting products increased, and the average branching degree decreased, as the reaction temperature, Al/(Fe + Zr) ratio, and reaction time increased. The melting points, crystallizations, and densities of the polymers decreased, and the average branching degree increased, when the Fe/Zr ratio increased. The 13C NMR and GPC results showed that there were no unreacted α‐olefins remaining in the resulting polymers because the percentage of low‐molar‐mass sections (C4–C10) of the oligomers obtained with this catalyst was very high (>70%). In addition, the formation of polymers with two melting points under different reaction conditions was examined in detail, and the results indicated that the two melting points of the polymers could be attributed to polyethylene with different branches. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 984–993, 2005
Synthesis and mass spectrometry characterization of centrally and terminally amine‐functionalized polyisobutylenes
Authors: Wollyung Kathleen M. , Wesdemiotis Chrys , Nagy Andras , Kennedy Joseph P. 
Published: January 2005

AbstractThis article reports the facile synthesis of novel terminally and centrally functionalized polyisobutylenes (PIBs) and the detailed characterization of the products by various mass spectrometry techniques. Specifically, HPIBCH2C(OH)CH3CH2NHCH3 and [HPIBCH2CH(OH)CH3CH2]2NCH3 were synthesized by the quantitative epoxidation of HPIBCH2C(CH3)CH2 and the subsequent conversion of the resulting epoxide with excess CH3NH2. Quaternization with CH3Cl of these mixtures of secondary and tertiary amines yielded exclusively HPIBCH2C(OCH3)CH3CH2N(CH3)2 from the secondary amine, whereas the tertiary (centrally functionalized) amine remained unchanged. Tandem mass spectrometry experiments provided unique insight into the precise connectivity of the functional end groups added to the PIB frame. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 946–958, 2005
Average termination rate coefficients in emulsion polymerization: Effect of compartmentalization on free‐radical lifetimes
Authors: Prescott Stuart W. , Ballard Mathew J. , Gilbert Robert G. 
Published: January 2005

AbstractA method is presented by which the time‐dependent average termination rate coefficient in an emulsion polymerization may be calculated as an appropriate average of the chain‐length‐dependent termination rate coefficients. The method takes advantage of the fact that the overall termination rate is dominated by terminations between rapidly moving short radicals and much slower long ones. This termination rate coefficient is suitable for use in the Smith–Ewart equations describing the compartmentalization of radicals in an emulsion polymerization. Rate data in emulsion polymerizations can be quantitatively interpreted if the kinetics fall into one of two categories: zero–one (showing compartmentalization; intraparticle termination is not rate‐determining) or pseudo‐bulk (no compartmentalization; intraparticle termination is rate‐determining). The new method can be used to interpret rate data for systems falling between these categories and also can be used to find termination rate coefficients from Monte Carlo simulations of termination kinetics. The latter is especially useful for predicting and understanding kinetics in controlled radical polymerizations in disperse media. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1076–1089, 2005
Synthesis and optical properties of green‐light‐emitting copolymers containing side‐chain oxadiazole units
Authors: Tzanetos Nikos P. , Kallitsis Joannis K. 
Published: January 2005

AbstractAtom transfer radical polymerization was used to prepare well‐defined vinyl polyoxadiazole homomacromonomers with a properly modified α‐dicarboxylic acid methyl ester as the initiator. Macromonomers of various molecular weights with narrow polydispersities in some cases were obtained, as proved by gel permeation chromatography (GPC). The structures of the obtained macromonomers were then identified with 1H NMR spectroscopy. These macromonomers were subsequently copolymerized with a dihydroxy anthracene based monomer by a polycondensation technique, and this resulted in polymacromonomers. Coil–rod–coil copolymers containing side‐chain anthracene and oxadiazole units were also synthesized by atom transfer radical polymerization. The resulting copolymers combined an anthracene derivative as the rigid block with a random copolymer of the desired anthracene‐ and/or oxadiazole‐based monomers as the flexible block. These copolymers were primarily characterized with GPC and 1H NMR techniques. Additionally, the optical properties of all these copolymers were investigated in detail, and they suggested energy transfer from the oxadiazole to the anthracene chromophores, which became much more efficient in the solid state. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1049–1061, 2005
Construction of a polymer skeleton that is cut in half by ionizing radiation
Authors: Shimizu Takashi , Ichikawa Tsuneki 
Published: January 2005

AbstractPolystyrene with a benzyl ester of carboxylic acid at the center of a polymer skeleton was synthesized by living radical polymerization. The initiator used had two functional groups for 2,2,6,6‐tetramethylpiperidinoxyl (TEMPO)‐mediated living radical polymerization on the benzyl and the carboxylic sides of the benzyl ester. Introduction of the benzyl ester changed the polystyrene from a crosslink type to a scission type polymer on γ‐irradiation. Irradiation of the polymer resulted in a binary change of the molecular weight because of the dissociative capture of secondary electrons by the benzyl ester, as:

The binary change of the molecular weight suggests that the polymer can be used as a new type of radiation resist with high sensitivity and spatial resolution to ionizing and high resistivity to plasma etching. The number of scissions per 100 eV radiation energy absorbed was 0.29, which was about one fourth of the yield of secondary electrons. The low efficiency was because of the recombination of polymer radicals generated by the dissociative electron attachment. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1068–1075, 2005
Polyelectrolyte multilayers prepared on hydrogel surfaces
Authors: Serizawa Takeshi , Sakaguchi Hirokazu , Matsusaki Michiya , Akashi Mitsuru 
Published: January 2005

AbstractPoly(vinyl alcohol) hydrogels were alternately immersed in aqueous solutions of oppositely charged polymers. The adsorption of the cationic dye methylene blue to the immersed hydrogels suggested the presence of a coating on the hydrogel surfaces. Static contact angles with an air bubble in water showed layer‐by‐layer growth of the films. The films could be transferred onto solid substrates for mechanical strength after the hydrogels were placed on the solid substrates, and this resulted in an estimation of the film thickness. The number of assembly steps could regulate the film thickness. We present here coatings of hydrogels with thin polymer films prepared by layer‐by‐layer assembly. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1062–1067, 2005