bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and characterization of mid‐ and end‐chain functional telechelics by controlled polymerization methods and coupling processes
Authors: Colak Demet , Cianga Ioan , Muftuoglu Ali Ekrem , Yagci Yusuf 
Published: November 2005

AbstractWell‐defined polystyrene‐ (PSt) or poly(ε‐caprolactone) (PCL)‐based polymers containing mid‐ or end‐chain 2,5 or 3,5‐ dibromobenzene moieties were prepared by controlled polymerization methods, such as atom transfer radical polymerization (ATRP) or ring opening polymerization (ROP). 1,4‐Dibromo‐2‐(bromomethyl)benzene, 1,3‐dibromo‐5‐(bromomethyl)benzene, and 1,4‐dibromo‐2,5‐di(bromomethyl)benzene were used as initiators in ATRP of styrene (St) in conjunction with CuBr/2,2′‐bipyridine as catalyst. 2,5‐Dibromo‐1,4‐(dihydroxymethyl)benzene initiated the ROP of ε‐caprolactone (CL) in the presence of stannous octoate (Sn(Oct)2) catalyst. The reaction of these polymers with amino‐ or aldehyde‐functionalized monoboronic acids, in Suzuki‐type couplings, afforded the corresponding telechelics. Further functionalization with oxidable groups such as 2‐pyrrolyl or 1‐naphthyl was attained by condensation reactions of the amino or aldehyde groups with low molecular weight aldehydes or amines, respectively, with the formation of azomethine linkages. Preliminary attempts for the synthesis of fully conjugated poly(Schiff base) with polymeric segments as substituents, by oxidative polymerization of the macromonomers, are presented. All the starting, intermediate, or final polymers were structurally analyzed by spectral methods (1H NMR, 13C NMR, and IR). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 727–743, 2006
Crosslinked epoxy materials exhibiting thermal remendablility and removability from multifunctional maleimide and furan compounds
Authors: Liu Ying‐Ling , Hsieh Chia‐Yun 
Published: December 2005

AbstractCrosslinked polymeric materials, which exhibit thermal remendability and removability through Diels–Alder (DA) and retro‐DA reactions, were obtained from using multifunctional maleimide and furan compounds as monomers. The synthesized monomers possess low melting points and good solubility in organo solvents to show excellent processing properties. The performance of DA and retro‐DA reactions were demonstrated with DSC and FTIR measurements. High performance of thermal remendablility and removability of the crosslinked materials were observed with SEM and solvent tests. These materials were applicable in advanced encapsulants and structural materials. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 905–913, 2006
Oxidation of poly(1,3‐cyclohexadiene): Influence of the polymer chain structure
Authors: Natori Itaru , Sato Hisaya 
Published: December 2005

AbstractThe influence of the microstructure on the oxidation of poly(1,3‐cyclohexadiene) (PCHD) homopolymer, obtained by anionic polymerization with alkyllithium/amine systems, was investigated for the first time. PCHD has a structure consisting of a main chain formed by 1,2‐addition (the 1,2‐CHD unit) and 1,4‐addition (the 1,4‐CHD unit). The molar ratio of 1,2‐CHD/1,4‐CHD units in the polymer chain strongly influenced the extent of oxidation of PCHD. A polymer chain with a high content of 1,4‐CHD units was easily oxidized by air and 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ). In contrast, the progress of oxidation was prevented in the case of PCHD containing 52% of 1,2‐CHD units. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 837–845, 2006
Homopolymer and block copolymer brushes on gold by living anionic surface‐initiated polymerization in a polar solvent
Authors: Sakellariou Georgios , Park Mikyoung , Advincula Rigoberto , Mays Jimmy W. , Hadjichristidis Nikos 
Published: December 2005

AbstractLiving anionic surface‐initiated polymerization on flat gold substrates has been conducted to create uniform homopolymer and diblock copolymer brushes. A 1,1‐diphenylethylene (DPE) self‐assembled monolayer was used as the immobilized precursor initiator. n‐BuLi was used to activate the DPE in tetrahydrofuran at –78 °C to initiate the polymerization of different monomers (styrene, isoprene, ethylene oxide, and methyl methacrylate). Poly(styrene) (PS) and poly(ethylene oxide) (PEO) in particular were first investigated as grafted homopolymers, followed by their copolymers, including poly(isoprene)‐b‐poly(methylmethacrylate) (PI‐b‐PMMA). A combined approach of spectroscopic (Fourier transform infrared spectroscopy, surface plasmon spectroscopy, ellipsometry, X‐ray photoelectron spectroscopy) and microscopic (atomic force microscopy) surface analysis was used to investigate the formation of the polymer brushes in polar solvent media. The chemical nature of the outermost layer of these brushes was studied by water contact angle measurements. The effect of the experimental conditions (solvent, temperature, initiator concentration) on the surface properties of the polymer brushes was also investigated. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 769–782, 2006
Nitroxide decomposition: Implications toward nitroxide design for applications in living free‐radical polymerization
Authors: Nilsen Aaron , Braslau Rebecca 
Published: November 2005

AbstractNitroxides bearing an α‐hydrogen decompose upon heating in a bimolecular reaction. A new mechanism is proposed for the decomposition of t‐butylisopropylphenyl nitroxide (TIPNO) involving the formation of a head‐to‐tail dimer, single electron transfer to form an oxammonium salt, epimerization to the corresponding nitrone, and elimination to form a conjugated oxime. This mechanism may provide insights into designing new nitroxides for use in controlled polymerization. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 697–717, 2006
Synthesis of a novel benzoxazine monomer‐intercalated montmorillonite and the curing kinetics of polybenzoxazine/clay hybrid nanocomposites
Authors: Yei Ding‐Ru , Fu Huei‐Kuan , Chen Wen‐Yi , Chang Feng‐Chih 
Published: December 2005

AbstractPolybenzoxazine (PBZ), which has a structure similar to that of phenolic resin, is formed through the thermal self‐curing of benzoxazine, that is through a heterocyclic ring opening reaction that requires no catalyst and releases no condensation byproducts. We have used the solvent blending method to prepare PBZ/clay nanocomposites possessing various clay contents. We synthesized a monofunctional benzoxazine monomer (MBM) and then treated the clay with this intercalation agent. The results of X‐ray diffraction (XRD) analysis indicated that MBM intercalated into the galleries of the clay; the nanocomposite possessed an exfoliated structure at 3% clay content. To better understand the curing kinetics of the PBZ/clay nanocomposites, we performed dynamic and isothermal differential scanning calorimetry (DSC) measurements. We describe the thermodynamics of the curing process, using all three of the Kissinger, Ozawa, and Kamal models. The Kissinger and Ozawa methods gave fairly close results for the calculated activation energies, which decreased upon increasing the clay content. The Kamal method, based on an autocatalytic model, suggested a total reaction order of between 2.4 and 2.8. The glass transition temperature (Tg) decreased upon increasing the clay content. Thermogravimetric analysis (TGA) indicated that the nanocomposites have higher decomposition temperatures than does the pristine PBZ; this finding suggests an enhancement in their thermal stability. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 347–358, 2006
Plasticized polylactide/clay nanocomposites. II. The effect of aging on structure and properties in relation to the filler content and the nature of its organo‐modification
Authors: Pluta Miroslaw , Paul Marie‐Amélie , Alexandre Michaël , Dubois Philippe 
Published: November 2005

AbstractPlasticized polylactide (PLA) – layered silicate nanocomposites were obtained by melt blending PLA with polyethylene glycol as plasticizer (20 wt %) and with different montmorillonite fillers: Cloisite® 20A, Cloisite® 25A, and Cloisite® 30B (from 1 to 10 wt %). Comparative samples of melt‐blended polylactide (without filler) and plasticized PLA with 20 wt % PEG were considered as well. Samples have been aged for 1 and 4 years and their chemical and physical characteristics were compared with not aged reference ones. It was found that molecular weight of the PLA decreased upon melt‐processing and aging, particularly when the Cloisite content increased, without a clear relation to the nature of the organo‐modifier. On the contrary, the PEG plasticizer was practically undegraded upon melt processing and aging. Structural studies revealed that plasticized PLA and plasticized PLA‐based nanocomposites are unstable in time of aging and undergo deplasticization. They showed, after aging, the presence of a thin PEG crystalline layer at the surface of the samples and improved the order in the PLA matrix to a higher extent in plasticized polylactide than in plasticized nanocomposite (due to clay stabilization effect). The amount of PEG diffusing toward sample surface was correlated with aging time, molecular weight of PLA matrix, and Cloisite® type, in clear relation to the extent of intercalation with PLA and PEG. Some modifications of the viscoelastic properties of PLA matrix, induced by the presence of both the nanoparticlate filler and the plasticizer, as well as a deterioration of the mechanical properties upon aging were observed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 312–325, 2006
Crosslinking induced by in‐situ coordination in acrylonitrile butadiene rubber/poly(vinyl chloride) alloy, filled with anhydrous copper sulfate particles
Authors: Shen Fei , Li Hui , Wu Chifei 
Published: December 2005

AbstractAcrylonitrile butadiene rubber (NBR)/poly(vinyl chloride) (PVC) alloy, filled with anhydrous copper sulfate (CuSO4) particles, was investigated for the first time. The material could be crosslinked in the existence of CuSO4 by heat pressing, without any other crosslink agents. The crosslinking in the material was induced by in situ coordination between nitrile groups of NBR and solid CuSO4 particles, which is thoroughly different from the traditional vulcanization of rubber materials. The coordination crosslinking is formed during heat pressing, other than in solutions, which is valuable for practical applications. The resulting material showed excellent tensile properties, and the maximum strength was close to 90 MPa. The CuSO4 particles act not only as crosslink agents, but also as reinforcing fillers in the polymer matrix. In this work, dynamic mechanical analysis, differential scanning calorimetry, Fourier transform infrared spectrum, X‐ray photoelectron spectroscopy, scanning electron microscope, energy‐dispersive X‐ray spectrum, equilibrium swelling method, and tensile test were performed for the characterization of the material. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 378–386, 2006
Process control systems in the chemical industry: Safety vs. security
Authors: Hahn Jeffrey , Guillen Donna Post , Anderson Thomas 
Published: December 2005

AbstractTraditionally, the primary focus of the chemical industry has been safety and productivity. However, recent threats to our nation's critical infrastructure have prompted a tightening of security measures across many different industry sectors. Reducing control system vulnerabilities against physical and cyber attack is necessary to ensure the safety, reliability, integrity, and availability of these systems. The U.S. Department of Homeland Security has developed a strategy to secure these vulnerabilities. Crucial to this strategy is the Control Systems Security and Test Center (CSSTC) established to test and analyze control systems and their components. In addition, the CSSTC promotes a proactive, collaborative approach to increase industry's awareness of standards, products, and processes that can enhance the security of control systems. This paper outlines measures that can be taken to enhance the cybersecurity of process control systems in the chemical sector. © 2005 American Institute of Chemical Engineers Process Saf Prog, 2006
Topological currents in ferromagnets and related systems – from the viewpoint of wave‐packet dynamics
Authors: Imura Ken‐Ichiro , Shindou Ryuichi 
Published: December 2005

AbstractWe reconsider the problem of the adiabatic motion of a wave packet of Bloch electrons, under a perturbation that is incommensurate with the lattice structure and varies slowly in time. Its effective dynamics is described by a set of equations of motion (EOM) with corrections due to the Berry phase. The underlying idea of our analyses is that various types of transport phenomena such as quantized, anomalous and spin Hall effects as well as specific sorts of polarization current can be best understood from the viewpoint of topological current associated with the Berry phase. Our EOM approach plays the role of bridge between the microscopic Berry phase and macroscopic topological transport. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the possibility of nonuniversal behavior in the 3D Ashkin–Teller model
Authors: Musiał Grzegorz , Rogiers Jos 
Published: December 2005

AbstractThe Monte Carlo simulations in the 3D Ashkin–Teller model on a cubic lattice are performed. The study is undertaken in the region where the universality class of the phase transitions has not been unambigously resolved yet. Using the finite‐size scaling relation between the magnetization, the temperature and the size of the system, the method of calculation of the critical exponent yh is proposed. Our preliminary results obtained for yh suggest a nonuniversal behavior, similarly as it was observed in the 2D case. Its value seems to change continuously in some interval approaching the Ising value near to all the tricritical points except one. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spin‐polarized charge transport through ionic clusters of magnetic oxides
Authors: Gehring G. A. , Lehmann‐Szweykowska A. , Wojciechowski R. J. , Wigen P. E. , Micnas R. 
Published: December 2005

AbstractWe analyze the spin‐controlled charge transfer through a heterostructure consisting of one octahedral and one tetrahedral iron–oxygen ionic clusters, which are site‐coupled, sharing an oxygen ion. A number of charge carriers can be manipulated by valence‐uncompensated doping. The electron‐energy structure of the clusters and that of the heterostructure are found on the basis of the Anderson model. Current–voltage (I–V ) characteristics, derived from the Landauer‐like formula, turn out to be highly sensitive to the position of the Fermi level. We also calculated the magnetoresistance for the heterostructure with different orientations of the magnetic field. The result confirmed the empirical data for Ca:YIG, which indicate strong anisotropy of the magnetoresistance. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the symmetry of a Preisach map
Authors: Gutowski Marek W. 
Published: December 2005

AbstractAt the very heart of the successful phenomenological model of magnetic hysteresis there is the so called Preisach distribution. In the existing literature it is implicitly assumed, that this distribution has a mirror symmetry. We show, by simple and convincing example, that this common assumption is plainly wrong. Dropping it, we gain the ability to model not only the usual hysteresis loops (major and minor) more accurately than ever before, but also those displaying the exchange bias effect, what is impossible within the framework of the symmetrical Preisach model. It is hoped, that our observation paves the way towards the unified description of all hysteretic systems, including, but not necessarily limited to, superconductors, (multi)layered structures, nanocrystalline materials, patterned media, and – perhaps – the other non‐magnetic hysteretic phenomena. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spin‐dependent transport through double‐island single‐electron devices
Authors: Weymann I. , Barnaś J. 
Published: December 2005

AbstractSpin‐dependent electronic transport through a double‐island device with Coulomb blockade is considered theoretically in the sequential tunneling regime. The analysis is based on the master equation method, with the corresponding tunneling rates calculated from the Fermi golden rule. Electric current and the resulting tunnel magnetoresistance are analyzed as a function of bias and gate voltages for different collinear magnetic configurations of the device. Furthermore, the nonequilibrium spin accumulation on the islands is calculated self‐consistently from the appropriate spin balance conditions. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transfer‐matrix study of critical properties of the Ising model following from the three‐cluster MFRG approach
Authors: Kamieniarz Grzegorz , Tomecka Daria M. 
Published: December 2005

AbstractUsing a transfer matrix technique and the Ising model, the predictions of the MFRG concept for clusters with linear size up to 21 have been tested for the three‐cluster MFRG approach. Even for small sizes of the clusters, the three‐cluster estimates of critical couplings and bulk critical exponents give the accuracy level equal to that of two‐cluster renormalization for much greater sizes. Performing the asymptotic analysis for the new data, the convergence of the surface critical exponent yhs towards the exact value is illustrated for the first time. Our improved method has enabled us to obtain the results for clusters with substantially greater sizes, to accelerate the calculations and also to confirm the reliability of the MFRG approach for the Ising model. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimal time‐points in clinical trials with linearly divergent treatment effects
Authors: Winkens Bjorn , Schouten Hubert J. A. , van Breukelen Gerard J. P. , Berger Martijn P. F. 
Published: November 2005

AbstractIn repeated measures studies, equidistant time‐points do not always yield efficient treatment effect estimators. In the present paper, the optimal allocation of time‐points is calculated for a small number of repeated measures, different covariance structures and linearly divergent treatment effects. The gain in efficiency of the treatment effect estimator by using optimally allocated time‐points instead of equidistant time‐points or by adding optimally spaced measures (at the expense of patients) is then computed. The assumed covariance structure is crucial for the results. For a compound symmetric covariance structure, a large gain in efficiency is obtained by adding repeated measures at the end of the study. For a first‐order auto‐regressive covariance structure, highly efficient treatment effect estimators are obtained with only two repeated measures, i.e. at the start and at the end of the study. For a first‐order auto‐regressive covariance structure including measurement error, the gain in efficiency by adding optimally spaced measures depends on the covariance parameter values. The gain in efficiency is similar with or without a random intercept. For a fixed study budget, the commonly used design with more than two equally spaced measures was never optimal for the linear cost function and covariance structures that were used. If the covariance structure is unknown, the optimal design based on a first‐order auto‐regressive covariance structure with measurement error is preferable in terms of robustness against misspecification of the covariance structure. The numerical results are illustrated by two examples. Copyright © 2005 John Wiley & Sons, Ltd.
Anatomical and functional significance of urogenital hiatus in primary urodynamic stress incontinence
Authors: Huang W.‐C. , Yang S.‐H. , Yang J.‐M. 
Published: December 2005

AbstractObjectivesTo explore the correlations of anatomical and functional sonographic parameters of urogenital hiatus in primary urodynamic stress incontinence.MethodsWe reviewed retrospectively our urodynamic database from July 1996 to June 2003 and identified subjects with primary urodynamic stress incontinence who had had anatomical assessment of the lower urinary tract and the central part of the pelvic floor by ultrasound. The morphological changes that had occurred in the central pelvic floor were determined by the measurement of genitohiatal angle, genitohiatal distance and anorectal angle.ResultsA total of 396 women with a mean age of 48.8 ± 10.7 (range, 26–82) years were included in the study. One hundred and eighteen subjects (29.8%) were postmenopausal. Stage I pelvic organ prolapse was found in 345 (87.1%) of the women, stage II in 19 (4.8%) and stage III in 32 (8.1%). The genitohiatal angle and genitohiatal distance were significantly and positively associated with resting and straining bladder neck angles. The genitohiatal angle was associated with bladder neck funneling and dependent cystocele during stress (r = 0.144, P = 0.016 and r = 0.140, P = 0.02, respectively), and it was negatively associated with functional profile length (r = −0.157, P = 0.012). The genitohiatal distance was negatively associated with functional profile length and maximum urethral closure pressure (r = −0.148, P = 0.018 and r = −0.227, P = 0.009, respectively). Increased genitohiatal distance was also related to a low Valsalva leak‐point pressure (r = −0.199, P = 0.02). Multivariate analysis revealed that resting bladder neck angle was the independent factor for genitohiatal angle and genitohiatal distance.ConclusionsIn primary urodynamic stress incontinence, an increased resting genitohiatal distance or genitohiatal angle on sonographic imaging implies anterior vaginal wall prolapse. In addition, an increased genitohiatal distance is associated with functional impairment of urethral closure. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
Überwachung von Plasmaprozessen durch OES. Monitoring of plasma processes by OES
Authors: Schmachtenberg Ernst , Hegenbart Andreas 
Published: November 2005

AbstractBei der industriellen Anwendung von Plasmaprozessen fehlt es häufig an einer Online‐Prozessüberwachung zur Prozessprotokollierung und Qualitätssicherung. Die Optische Emissionsspektroskopie (OES) bietet eine relativ einfache Möglichkeit, dieses Problem in vielen Fällen zu lösen. Das Verfahren beeinflusst die Prozesse selbst nicht, ist äußerst robust und preiswert. Die OES wurde für verschiedene Anwendungen beim Einsatz Mikrowellen‐angeregter Plasmen, zur gezielten Funktionalisierung (Behandlung und Beschichtung) von Kunststoffbauteilen, untersucht. Es konnte gezeigt werden, dass die OES zur Überwachung der Qualität von Sauerstoff‐Plasmaprozessen, z. B. bei der Aktivierung von Kunststoffbauteilen, eingesetzt werden kann. Darüber hinaus eignet sich die OES zur Online‐Qualitätssicherung bei der Erzeugung glasartiger Plasmapolymerschichten mit Hilfe der Mikrowellen‐angeregten Plasmapolymerisation, unter Verwendung eines Prozessgasgemisches aus HMDSO und Sauerstoff. Es gibt klare Zusammenhänge zwischen der chemischen Zusammensetzung, der Oberflächenspannung sowie der Rauigkeit der erzeugten Schichten und der Emission bestimmter chemischer Spezies im Plasma.