bluuebunny/crossref_metadata_2025_split huggingface dataset:
A study on the preparation of polymer/montmorillonite nano‐composite materials by photo‐polymerization
Authors: Huimin Wang , Minghua Mei , Yongcai Jiang , Qingshan Li , Xiaohong Zhang , Shikang Wu 
Published: August 2002

AbstractThe preparation of polymer/montmorillonite intercalation composite materials was studied by two kinds of photo‐polymerization reaction (photo‐acid generation and photo‐radical generation). Small‐angle X‐ray diffraction was used for the structural characterization of montmorillonite contained in the products. Results indicated that, after chemical modification of montmorillonite, the monomer (methyl methacrylate) and the prepolymer (m‐cresol/HMMM) were able to intercalate into the layers of clay and to polymerize ‘in situ’, thus producing photo‐polymerized composite materials. The advantages and shortcomings of the method of photo‐polymerization for the preparation of these composite materials are discussed.© 2001 Society of Chemical Industry
Interpolymer complex polyampholytic hydrogel of chitosan and carboxymethyl cellulose (CMC): synthesis and ion effect
Authors: Yan Lifeng , Qian Fang , Zhu Qingshi 
Published: August 2002

AbstractInterpolymer complexes of chitosan and carboxymethyl cellulose were synthesized by γ‐irradiation in acetic acid/water solution, using methylenebisacrylamide (MBAAM) as a crosslinker. FTIR and atomic force microscopy were used to determine their structures. The hydrogels swell in water, and their swelling behaviour is strongly affected by the ion strength of the solution, which indicates that a polyampholytic hydrogel is formed.© 2001 Society of Chemical Industry
A methodology for the design of photovoltaic water supply systems
Authors: Vilela O. C. , Fraidenraich N. 
Published: August 2002

AbstractPhotovoltaic pumping systems are used nowadays as a valuable alternative to supply water to communities living in remote rural areas. Owing to the seasonal variation and the stochastic behavior of solar radiation, at certain times the supply of water may not be able to meet demand. A study has been made of the relationship between water pumping capacity, reservoir size and water demand, for a given water deficit. As a result, curves of equal water deficit (iso‐deficit lines) can be obtained for various combinations of PV pumping capacity and reservoir size. A methodology to generate those curves is described, using as its main tool the characteristic curve of the system, that is, the relationship between water flow and collected solar radiation. The characteristic curve represents the combined behavior of the water pumping system and the well. The influence of the minimum collected solar radiation level, necessary to start the system's operation (the critical radiation level IC), is also analyzed. Results show that PV pumping systems with different characteristic curves, but with the same critical levels, yield the same set of iso‐deficit lines. This drastically reduces the number of necessary solutions to those corresponding to a few values of IC. Iso‐deficit lines, calculated for the locality of Recife (PE), Brazil, are used to illustrate the sizing procedure PV water supply systems. Copyright © 2001 John Wiley & Sons, Ltd.
Characteristics and educational support needs of underrepresented gifted adolescents
Authors: Stormont Melissa , Stebbins Molly S. , Holliday Gregory 
Published: August 2002

AbstractThe purpose of this article is to present the characteristics and needs of adolescent students who are underrepresented in gifted programs. The specific populations of underrepresented gifted youth who will be addressed in this article include young women, students with learning disabilities, and students living in poverty. The academic and social‐emotional needs of students from underrepresented populations will be presented, followed by strategies professionals can use to support these students. The importance of developing more sensitive identification and outreach programs for these youth is clearly illuminated by their social‐emotional characteristics and academic underachievement. It is important to create support strategies for students at the secondary level, as this may be their last point of entry in the educational system. © 2001 John Wiley & Sons, Inc.
Direct functionalization of polyisobutylene by living initiation with α‐methylstyrene epoxide
Authors: Song J. , Bódis J. , Puskas J. E. 
Published: August 2002

AbstractThis article describes the synthesis and characterization of polyisobutylene (PIB) carrying one primary hydroxyl head group and a tertiary chloride end group, [PhC(CH3)(CH2OH)–PIB–CH2C(CH3)2Cl] prepared with direct functionalization via initiation. The polymerization of isobutylene was initiated with the α‐methylstyrene epoxide/titanium tetrachloride system. Living conditions were obtained from −75 to −50 °C (198–223 K). Low molecular weight samples (number‐average molecular weight ∼ 4000 g/mol) were prepared under suitable conditions and characterized by Fourier transform infrared and 1H NMR spectroscopy. The presence of primary hydroxyl head groups in PIB was verified by both methods. Quantitative Fourier transform infrared with 2‐phenyl‐1‐propanol calibration and 1H NMR performed on both the hydroxyl‐functionalized PIB and its reaction product with trimethylchlorosilane showed that each polymer chain carried one primary hydroxyl head group. The synthetic methodology presented here is an effective and simple route for the direct functionalization of PIB. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1005–1015, 2002
Production of crosslinked, hollow nanoparticles by surface‐initiated living free‐radical polymerization
Authors: Blomberg Susanne , Ostberg Sofia , Harth Eva , Bosman Anton W. , Van Horn Brooke , Hawker Craig J. 
Published: August 2002

AbstractSurface‐initiated living free‐radical polymerization is employed in a multistep procedure to prepare hollow polymeric nanocapsules. Initially, trichlorosilyl‐substituted alkoxyamine initiating groups are attached to the surface silanol groups of silica nanoparticles. This surface layer of initiating groups is then used to grow functionalized linear chains leading to a core–shell morphology. The choice of functional groups is governed by their ability to undergo facile crosslinking reactions, with both active ester and benzocyclobutene groups being examined. Under either chemical or thermal conditions, the reaction of these functionalities gives a crosslinked polymeric shell that is covalently attached to, and surrounds, the central silica core. Removal of the silica core with HF then gives the hollow polymeric nanocapsules, which are stable under solvent dissolution and thermal treatment because of their crosslinked structure. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1309–1320, 2002
Synthesis and characterization of well‐defined ABC‐type triblock copolymers via atom transfer radical polymerization and stable free‐radical polymerization
Authors: Tunca U. , Erdogan T. , Hizal G. 
Published: August 2002

AbstractAn asymmetric difunctional initiator 2‐phenyl‐2‐[(2,2,6,6 tetramethylpiperidino)oxy] ethyl 2‐bromo propanoate (1) was used for the synthesis of ABC‐type methyl methacrylate (MMA)‐tert‐butylacrylate (tBA)‐styrene (St) triblock copolymers via a combination of atom transfer radical polymerization (ATRP) and stable free‐radical polymerization (SFRP). The ATRP‐ATRP‐SFRP or SFRP‐ATRP‐ATRP route led to ABC‐type triblock copolymers with controlled molecular weight and moderate polydispersity (Mw/Mn < 1.35). The block copolymers were characterized by gel permeation chromatography and 1H NMR. The retaining chain‐end functionality and the applying halide exchange afforded high blocking efficiency as well as maintained control over entire routes. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2025–2032, 2002
Polymerizable anthracene derivatives for labeling emulsion copolymers
Authors: Liu Ronghua , Winnik Mitchell A. , Di Stefano Frank , Vanketessan Jai 
Published: August 2002

AbstractWe describe the synthesis of three anthracene–methacrylate monomers [9‐methacryloxymethyl‐10‐methyl anthracene (4), 9‐methacryloxyethyloxymethyl‐10‐methyl anthracene (5), and 9‐methacryloxy‐10‐methyl anthracene (6)] as well as their emulsion copolymers containing butylacrylate. When films prepared from latex dispersions containing 4 or 5 were heated, the anthracene (An) group was cleaved from the polymer at temperatures above 120 °C. Lower temperatures induced this reaction when strong acids were present. In 4 and 5, the polymerizable group is connected to the An ring via a 9‐CH2O linkage. The cleavage reaction requires more stringent conditions when the connection involves a benzylic ether (5) instead of a benzylic ester. Polymers prepared from 6, with an AnO bond, were stable for 1 h at 150 °C in the presence of 0.5 wt % p‐toluene sulfonic acid. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1495–1504, 2001
Novel refreshable N‐halamine polymeric biocides containing imidazolidin‐4‐one derivatives
Authors: Sun Yuyu , Chen Tay‐Yuan , Worley S. D. , Sun Gang 
Published: August 2002

AbstractA novel cyclic‐amine monomer, 1‐acryloyl‐2,2,5,5‐tetramethylimidazolidin‐4‐one (ACTMIO), was synthesized in a good yield through the reaction of acryloyl chloride with 2,2,5,5‐tetramethylimidazolidin‐4‐one and was fully characterized with Fourier transform infrared and 1H NMR studies. ACTMIO was copolymerized with several widely used acrylic and vinyl monomers under ordinary conditions. In the presence of triallyl‐1,3,5‐triazine‐2,4,6(1H,3H,5H)‐trione, ACTMIO was easily grafted onto most textile fabrics. After regular chlorine bleach treatment, N‐halamine derivatives of the corresponding polymeric materials exhibited antibacterial properties against Escherichia coli, and these properties were durable and refreshable with chlorine bleaching. The relationship between the structures and antibacterial properties of the samples is further discussed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3073–3084, 2001
Elastic behavior of bimodal poly(dimethylsiloxane) networks
Authors: Zhang Lin‐Xi , Jiang Zhou‐Ting , Zhao De‐Lu 
Published: August 2002

AbstractThe rubberlike elastic behavior of bimodal poly(dimethylsiloxane) (PDMS) networks was investigated by the Monte Carlo simulation method and enumeration calculation method on the basis of the rotational‐isomeric‐state (RIS) model. These bimodal PDMS networks consist of short chains (chain length from 10 to 20) as well as long chains (chain length equal to 150). For long PDMS chains, through generating many PDMS conformations in the equilibrium state using the Monte Carlo simulation method we can obtain the average Helmholtz free energy and the average energy. For short PDMS chains with chain lengths from 10 to 20, as the total number of conformations is only from 6.56 × 103 to 3.87 × 108, we adopt the enumeration calculation method. The deformation is partitioned nonaffinely between the long and short chains, and this partitioning can be determined by requiring the free energy of the deformed network to be minimized. Chain dimensions and thermodynamic statistical properties of bimodal PDMS networks at various elongation ratios are discussed. We find that elastic force f increases with elongation ratio λ; the energy contribution fu to elastic force is significant, and the ratio of ranges from 0.15 to 0.36 at T = 343 K. In the meantime, elastic force f increases with the average energy 〈U〉. The energy change in the process of tensile elongation is taken over, which has been ignored in previous theories. Our calculations may provide some insights into the phenomena of rubberlike elasticity of bimodal networks. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 105–114, 2002
Constant loss in Brillouin spectra of polymers
Authors: Kisliuk A. , Novikov V. N. , Sokolov A. P. 
Published: August 2002

AbstractThe polarized (VV) and depolarized (VH) light scattering spectra of polyisobutylene, poly(methyl methacrylate), and glycerol were measured in the gigahertz frequency range at temperatures below and above the glass transition. Both VV and VH spectra exhibit a significant constant loss contribution that appears as a frequency‐independent imaginary part of the susceptibility spectrum. Existence of the frequency‐independent susceptibility in VV spectra below the Brillouin lines suggests that the constant loss also appears in mechanical relaxation in the gigahertz frequency range. Intensity of the constant loss increases strongly with temperature. Analysis of the spectra and literature data suggests that the constant loss can be general for many glass‐forming systems, but it is hidden in many cases by other relaxation contributions. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 201–209, 2002
Volume‐exclusion effects in polyethylene blends filled with carbon black, graphite, or carbon fiber
Authors: Thongruang Wiriya , Balik C. Maurice , Spontak Richard J. 
Published: August 2002

AbstractConductive polymer composites possessing a low percolation‐threshold concentration as a result of double percolation of a conductive filler and its host phase in an immiscible polymer blend afford a desirable alternative to conventional composites. In this work, blends of high‐density polyethylene (HDPE) and ultrahigh molecular weight polyethylene (UHMWPE) were used to produce ternary composites containing either carbon black (CB), graphite (G), or carbon fiber (CF). Blend composition had a synergistic effect on electrical conductivity, with pronounced conductivity maxima observed at about 70–80 wt % UHMWPE in the CB and G composites. A much broader maximum occurred at about 25 wt % UHMWPE in composites prepared with CF. Optical and electron microscopies were used to ascertain the extent to which the polymers, and hence filler particles, are segregated. Differential scanning calorimetry of the composites confirmed that the constituent polymers are indistinguishable in terms of their thermal signatures and virtually unaffected by the presence of any of the fillers examined here. Dynamic mechanical analysis revealed that CF imparts the greatest stiffness and thermal stability to the composites. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1013–1023, 2002
Survivorship and discourses of identity
Authors: Little Miles , Paul Kim , Jordens Christopher F.C. , Sayers Emma‐Jane 
Published: August 2002

AbstractPersonal identity is self‐evidently important to us all. Identity is a philosophically complex subject, but there is some agreement that memory, embodiment and continuity are essential components. The sense of memory includes ‘future memory’, the kind of memory we would like to construct for ourselves as our lives proceed. While the sense of personal identity is internal to the individual, a sense of that person's identity exists in the minds of others. Extreme experiences threaten the element of continuity, because they may bring bodily changes as well as cognitive changes that challenge central values. Restoring or preserving continuity is a major task for survivors. The ways in which people experience discontinuity because of cancer illness, and the ways in which they manage this experience emerges from the narratives of the survivors of cancer and in the narratives of health care workers who look after them. People manage discontinuity by reference to stable ‘anchor points’ in their beliefs and values; by re‐constructing versions of their pre‐experience identities, drawing on past memory and finding ways to preserve a continuity between past memory, present experience and constructions of the future; by using the experience to develop established facets of identity; and by imbuing the experience with meaning and recognising the enlarged identity made possible by survival. Those who cannot achieve a sense of continuity may feel alienated from themselves, their friends and family. All these methods of management may be used by one person to negotiate the post‐experience identity in its different social interactions.The experience of the survivor can be further understood by recognising the challenge posed by extreme experience to the sense of continuity of both embodied self and memory. A satisfactory discourse of survival has yet to enter the public domain. This lack adds to the burdens of survivors, including those who have survived cancer. Copyright © 2002 John Wiley & Sons, Ltd.
Psychological adjustment of ‘surgery‐only’ pediatric neuro‐oncology patients: a retrospective analysis
Authors: Meyer Eugene A. , Kieran Mark W. 
Published: August 2002

AbstractA recent increase in diagnoses of pediatric neuro‐oncology tumors combined with recent advancements in medical treatment of such tumors has resulted in a growing cohort of pediatric brain tumor survivors. These survivors are at risk for short and long‐term psychological adjustment problems. Most studies regarding these survivors have focused on children who have received combinations of surgery, radiation, and chemotherapy as medical treatment. The sub‐group of pediatric neuro‐oncology patients who receive surgery as the only form of medical treatment has not been closely followed for adjustment problems. In this study, data were retrospectively collected from semi‐structured clinical interviews with 34 ‘surgery‐only’ pediatric neuro‐oncology patients who were 2 weeks to 5 years off medical treatment for their tumor. These data suggest that these survivors may be experiencing significant short and long‐term mood, behavioral, and academic adjustment problems in comparison to national averages for children regarding these issues. Additional research examining the psychological adjustment process for surgery‐only pediatric neuro‐oncology patients is needed to validate these preliminary findings and facilitate the development of targeted interventions to address the identified adjustment problems. Copyright © 2002 John Wiley & Sons, Ltd.
Quality of life in childhood cancer survivors
Authors: Zebrack Brad J. , Chesler Mark A. 
Published: August 2002

AbstractThe successful treatment for children with cancer has greatly increased the survival rates for these young people compared to children diagnosed with cancer 30 years ago. These new medical realities direct attention to the psychosocial consequences of successful treatment and subsequent survival. In this paper, quality of life in 176 childhood cancer survivors (age 16–28) is assessed using a survey instrument designed for cancer survivors. In addition, the instrument is evaluated for its utility with this population.Survivors indicate that symptoms often associated with treatment are at a minimum but that other long‐term effects like fatigue, aches, and pain negatively impact quality of life. They rate themselves high on happiness, feeling useful, life satisfaction and their ability to cope as a result of having had cancer but their hopefulness is tempered by uncertainty. Whereas the salience of spiritual and religious activities appears to be low, having a sense of purpose in life and perceiving positive changes as a result of cancer are associated with positive quality of life. A lower valence of physical concerns reflects the vitality and positive life outlook of a young population. Copyright © 2002 John Wiley & Sons, Ltd.
Permafrost–glacial evolution during the Holocene in the Italian Central Alps
Authors: Guglielmin M. , Cannone N. , Dramis F. 
Published: August 2002

AbstractThis paper discusses the Holocene evolution of two sites in the Central Italian Alps, the Foscagno Valley and the Stelvio–Livrio area, in terms of the interaction between permafrost distribution and glacial history. The applicability of phytosociological vegetation survey to investigate recent glacial evolution where geomorphological evidence is poor or totally absent is also illustrated. Bottom temperature of snow measurements and detailed geomorphologic survey and air‐photo interpretation were carried out in the Stelvio–Livrio area. Boreholes were drilled in each site, one (24 m deep) in the Foscagno rock glacier (2510 m ASL), the second (100.3 m deep) in dolostone‐limestone bedrock at the Stelvio Pass (3000 m ASL). The latter borehole is a component of the PACE European Permafrost Monitoring Network. In Foscagno Valley, the formation of permafrost during a cold and dry phase of the Holocene allowed the preservation of an ice body which otherwise would have disappeared. More recently, a Little Ice Age glacier advance, whose exact location and extension were defined by means of the analysis of vegetal associations, induced some degradation in the permafrost. In the Stelvio–Livrio area, a cold‐based glacier apparently had much less influence on the local permafrost evolution and thermal regime. Copyright © 2001 John Wiley & Sons, Ltd.RÉSUMÉL'évolution holocène de deux sites des Alpes centrales italiennes, la vallée de Foscagno et la région de Stelvio‐Livrio, est discutée pour contribuer à la compréhension des relations entre la distribution du pergélisol et l'histoire glaciaire. Un autre but de l'étude était de vérifier la possibilité d'utiliser des relevés phytosociologiques pour comprendre l 'évolution récente glaciaire de zones où des évidences géomorphologiques sont maigres ou totalement absentes et de mieux comprendre ainsi la distribution du pergélisol. Des mesures BTS, des levés géomorphologiques détaillés et des interprétations de photos aériennes de la zone Stelvio‐Livrio ont été réalisés. Enfin, deux sondages ont été implantés : l'un (24 m de profondeur) dans le glacier rocheux de Foscagno (2510 m) et l'autre dans le substratum rocheux (100.3 m de profondeur) du Col du Stelvio (3000 m). Ce dernier sondage fait partie du réseau européen PACE de surveillance du pergélisol. Des levés phytosociologiques ont été réalisés dans les deux zones. Dans la vallée de Foscagno, la formation du pergélisol pendant une phase froide et aride de l'Holocène a permis la conservation d'un corps de glace qui, autrement, aurait disparu. Plus récemment, une avancée glaciaire pendant le Petit Age Glaciaire (dont la localisation et l'exacte extension ont été reconnues par les études phytosociologiques) a provoqué la dégradation du pergélisol. Dans la zone de Stelvio‐Livrio, un glacier à base froide a apparemment beaucoup moins influencé la distribution du pergélisol et son régime thermique. Copyright © 2001 John Wiley & Sons, Ltd.