bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of pH‐sensitive surfactants by the terpolymerization of methacrylic acid, methoxy poly(ethylene glycol) methacrylate, and lauryl methacrylate: Initiator effect and reactivity ratio study
Authors: Restrepo A. Sabrina , Pinzón Neissa M. , Ju Lu‐Kwang 
Published: May 2004

AbstractFor the development of pH‐sensitive surfactants to be used in water‐in‐oil fermentation, the free‐radical terpolymerization of methacrylic acid (MAA), methoxy poly(ethylene glycol) methacrylate (MPEGMA), and lauryl methacrylate (LMA), at a molar ratio of 1.0:0.04:0.76, was studied with two initiators, azobisisobutyronitrile (AIBN) and hydrogen peroxide, at different concentrations. The polymer synthesized with 0.45% AIBN as the initiator was the most promising, giving similar conversions of all three monomers throughout the 10‐h polymerization. The subsequent study on AIBN‐initiated systems indicated that MPEGMA caused an increase‐then‐decrease profile of the MAA conversion with a plateau around an ethylene glycol/MAA ratio of 1–2. This observation was fairly consistent with the well‐known type II template polymerization of poly(ethylene glycol) (PEG)–MAA systems. The reactivity ratios obtained in this study suggested that the polymer synthesized with AIBN as the initiator had a structure of alternating blocks of MAA and LMA, with isolated PEG grafts. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2950–2959, 2004
New series of highly phenyl‐substituted polyfluorene derivatives for polymer light‐emitting diodes
Authors: Peng Qiang , Xie Minggui , Huang Yan , Lu Zhiyun , Xiao Dan 
Published: May 2004

AbstractA new series of highly phenyl‐substituted polyfluorene derivatives were synthesized and characterized. The resulting polymers were amorphous and showed excellent solubility in common organic solvents, such as chloroform, tetrahydrofuran, xylene, toluene, chlorobenzene, and so forth. All possessed satisfied thermal stability with glass‐transition temperatures (Tg's) in the range of 79–115 °C. They emitted blue light with photoluminescent (PL) maximum peaks at about 408–412 nm in thin films. The PL efficiencies of the polymer films were measured around 30–33%. The highly phenylated pendants improved the Tg of polyfluorene without forming defects in the polymers and reduced their tendency to form aggregate/excimers. Polymer light‐emitting diodes were fabricated from these polymers with the configuration of indium tin oxide/polyethylenedioxythiophene:polystyrene sulfonic acid/polymer/Ba/Al, which emitted bright blue light with maximum peaks at 418–420 nm. The maximum external quantum efficiencies of these devices were 0.41–0.6%. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2985–2993, 2004
Side‐chain functionalized polymers containing bipyridine coordination sites: Polymerization and metal‐coordination studies
Authors: Carlise Joseph R. , Weck Marcus 
Published: May 2004

AbstractMonomers containing (trisbipyridine) ruthenium(II), (bisbipyridine) palladium(II), and heteroleptic ruthenium complexes were synthesized and polymerized via ruthenium‐catalyzed ring‐opening metathesis polymerization in nonpolar solvents. The solubility of the resulting polyelectrolytes in nonpolar solutions could be tuned by alkyl functionalization of the ligands around the metal centers. These polymers are the first polynorbornenes containing a 2,2′‐bipyridine‐based metal complex at each repeating unit and might be used in numerous applications, including luminescent and electroluminescent materials. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2973–2984, 2004
Living cationic polymerization of vinyl ethers with a urethane group
Authors: Namikoshi Takeshi , Hashimoto Tamotsu , Kodaira Toshiyuki 
Published: May 2004

AbstractTo study the possibility of living cationic polymerization of vinyl ethers with a urethane group, 4‐vinyloxybutyl n‐butylcarbamate (1) and 4‐vinyloxybutyl phenylcarbamate (2) were polymerized with the hydrogen chloride/zinc chloride initiating system in methylene chloride solvent at −30 °C ([monomer]0 = 0.30 M, [HCl]0/[ZnCl2]0 = 5.0/2.0 mM). The polymerization of 1 was very slow and gave only low‐molecular‐weight polymers with a number‐average molecular weight (Mn) of about 2000 even at 100% monomer conversion. The structural analysis of the products showed occurrence of chain‐transfer reactions because of the urethane group of monomer 1. In contrast, the polymerization of vinyl ether 2 proceeded much faster than 1 and led to high‐molecular‐weight polymers with narrow molecular weight distributions (MWDs ≤ ∼1.2) in quantitative yield. The Mn's of the product polymers increased in direct proportion to monomer conversion and continued to increase linearly after sequential addition of a fresh monomer feed to the almost completely polymerized reaction mixture, whereas the MWDs of the polymers remained narrow. These results indicated the formation of living polymer from vinyl ether 2. The difference of living nature between monomers 1 and 2 was attributable to the difference of the electron‐withdrawing power of the carbamate substituents, namely, n‐butyl for 1 versus phenyl for 2, of the monomers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2960–2972, 2004
Monomer reactivity ratios for acrylonitrile–methyl acrylate free‐radical copolymerization
Authors: Wiles K. B. , Bhanu V. A. , Pasquale A. J. , Long T. E. , McGrath J. E. 
Published: May 2004

AbstractNonlinear monomer reactivity ratios for the homogeneous free‐radical copolymerization of acrylonitrile and methyl acrylate were determined from 1H NMR and real‐time Fourier transform infrared (FTIR) analyses. All 1H NMR data were obtained on polymers isolated at low conversions (<10%), whereas the FTIR data were collected in situ. The copolymerizations were conducted in N,N‐dimethylformamide at 62 °C and were initiated with azobisisobutyronitrile. The real‐time FTIR technique allowed for many data points to be collected for each feed composition, which enabled the calculation of copolymer compositions (dM1/dM2) with better accuracy. Monomer reactivity ratios were estimated with the Mayo–Lewis method and then were refined via a nonlinear least‐squares analysis first suggested by Mortimer and Tidwell. Thus, monomer reactivity ratios at the 95% confidence level were determined to be 1.29 ± 0.2 and 0.96 ± 0.2 for acrylonitrile and methyl acrylate, respectively, which were valid under the specific system conditions (i.e., solvent and temperature) studied. The results are useful for the development of acrylonitrile (<90%) and methyl acrylate, melt‐processable copolymer fibers and films, including precursors for carbon fibers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2994–3001, 2004
QCD‐like gauge dynamics from gravity duals
Authors: Evans N. 
Published: May 2004

AbstractWe describe attempts to study QCD‐like gauge dynamics using a deformed version of the AdS/CFT Correspondence. The Yang Mills* geometry is dual to a gauge theory that is non‐supersymmetric Yang Mills in the infra‐red but reverts to N = 4 super Yang Mills in the ultra‐violet. The geometry describes a discrete, calculable glueball spectrum with a mass gap. Wilson loops in the geometry display QCD string breaking.
A gravity dual of chiral symmetry breaking
Authors: Babington J. , Erdmenger J. , Evans N. , Guralnik Z. , Kirsch I. 
Published: May 2004

AbstractWe establish a holographic description of chiral symmetry breaking for a particular confining large N non‐supersymmetric gauge theory with matter in the fundamental representation. The gravity dual of this theory is obtained by introducing a D7‐brane probe into a deformed Anti‐de Sitter background found by Constable and Myers. We numerically compute the $\bar\psi\psi$ condensate and meson spectrum by solving the equation of motion of the D7‐brane probe in this background. We find a symmetry breaking condensate as well as the associated, pion‐like, Goldstone boson in the limit of small quark mass. The existence of the condensate ensures that the D7‐brane never reaches the naked singularity at the origin of the deformed AdS space.
UV/IR mixing, noncommutative instabilites and closed strings
Authors: López E. 
Published: May 2004

AbstractThe leading UV/IR mixing effects on noncommutative field theories modify the dispersion relations and, depending on their sign, may cause the appearance of unstable modes. For noncommutative gauge theories on D‐branes, this phenomenon is able to capture important information about the closed string spectrum of the parent string theory. We analyse noncommutative D‐branes on nonsupersymmetric orbifolds and twisted circle backgrounds. We find that the sign of the leading UV/IR mixing effects is governed by the mass gap between the lowest modes in the NSNS and RR closed string towers. For noncommutative D3‐branes at orbifolds we obtain a stronger result: a one to one correspondence between noncommutative instabilities and closed string tachyons.
Gauge instantons from open strings
Authors: Frau M. , Lerda A. 
Published: May 2004

AbstractIn this contribution we describe how to obtain instanton effects in four dimensional gauge theories by computing string scattering amplitudes in D3/D(‐1) brane systems. In particular we show that the disks with mixed boundary conditions, which are typical of the D3/D(‐1) system, are the sources for the classical instanton solution.
Special‐holonomy manifolds and quartic‐curvature string corrections
Authors: Stelle K.S. 
Published: May 2004

AbstractThe quartic‐curvature corrections derived from string theory have a very specific impact on the geometry of target‐space manifolds of special holonomy. In the cases of Calabi‐Yau manifolds and D = 7 manifolds of G2 holonomy, we show how the corrections conspire to preserve the unbroken supersymmetry of these backgrounds.
Vibrating sample magnetometer using a multilayer piezoelectric actuator
Authors: Shin K. H. , Park K. I. , Kim Y. , Sa‐Gong G. 
Published: May 2004

AbstractA vibrating sample magnetometer with a multilayer piezoelectric actuator as vibrating mechanism is proposed in this paper. The piezoelectric vibrating mechanism was adopted to achieve both high sensitivity and small‐sizing of VSM. By applying an alternating voltage to the multilayer piezoelectric actuator, the quartz cantilever is vibrated transversely. The magnetic specimen on the end of the cantilever was vibrated ∼3.5 mm at 79 Hz. The proposed VSM has high sensitivity due to an extremely large vibrating amplitude and small size (30 × 25 × 25 cm3). (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear resonant magneto‐optical effects in alkaline metal vapors in the strong bichromatic laser radiation field
Authors: Karagodova T. Ya. , Kuptsova A. V. 
Published: May 2004

AbstractResults of computer simulations of the spectra of magneto‐optical rotation (MOR) of the polarization plane for both components of intense bichromatic laser radiation are presented. Dependences of MOR on light intensity and the external magnetic field strength have been investigated. The simulations are based on the theory and method published earlier. Our results coincide with experimental results known from literature. This suggests that new peculiarities of MOR in alkaline vapors obtained by computer simulations can be observed in the natural experiments. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Exploration of the free‐energy surface of a three‐helix peptide with stochastic optimization methods
Authors: Herges T. , Schug A. , Wenzel W. 
Published: May 2004

AbstractWe report our recent efforts to develop all‐atom forcefields that can be used to predict the three‐dimensional, tertiary structure of proteins using stochastic optimization methods. We have analyzed an approximate free‐energy surface of the 36‐residue headpiece of the villin protein and found configurations that were lower in energy than the NMR configuration. We adjusted the parameters of the solvent model to stabilize the NMR structure using a decoy approach. We arrived at a free‐energy surface that is characterized by a deep folding funnel populated by different three‐helix structures, one of which is very similar to the NMR structure. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Orientational ordering in physisorbed molecular layers induced by surface geometry and confinement
Authors: Ramseyer C. , Pouthier V. , Humbert J. , Girardet C. 
Published: May 2004

AbstractMonte Carlo calculations are performed to study the orientational ordering of a model two‐dimensional molecular admonolayer confined between two monatomic steps of a square substrate. Aside from the orientational influence of the substrate on the molecular axes, we show strong competition between the lateral interactions and the confinement potential due to the steps, which is responsible for more or less abrupt orientational transitions depending on the strength of the various interactions, the width of the confinement, and the temperature. An application to the adsorption of N2monolayer adsorbed on Cu/CuO stripe substrate is discussed. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Reversible coagulation–fragmentation processes and random combinatorial structures: Asymptotics for the number of groups
Authors: Erlihson Michael M. , Granovsky Boris L. 
Published: May 2004

AbstractThe equilibrium distribution of a reversible coagulation‐fragmentation process (CFP) and the joint distribution of components of a random combinatorial structure (RCS) are given by the same probability measure on the set of partitions. We establish a central limit theorem for the number of groups (= components) in the case a(k) = qkp−1, k ≥ 1, q, p > 0, where a(k), k ≥ 1, is the parameter function that induces the invariant measure. The result obtained is compared with the ones for logarithmic RCS's and for RCS's, corresponding to the case p < 0. © 2004 Wiley Periodicals, Inc. Random Struct. Alg. 2004
Is constraint satisfaction over two variables always easy?
Authors: Engebretsen Lars , Guruswami Venkatesan 
Published: May 2004

AbstractBy the breakthrough work of Håstad [J ACM 48(4) (2001), 798–859], several constraint satisfaction problems are now known to have the following approximation resistance property: Satisfying more clauses than what picking a random assignment would achieve is NP‐hard. This is the case for example for Max E3‐Sat, Max E3‐Lin, and Max E4‐Set Splitting. A notable exception to this extreme hardness is constraint satisfaction over two variables (2‐CSP); as a corollary of the celebrated Goemans‐Williamson algorithm [J ACM 42(6) (1995), 1115–1145], we know that every Boolean 2‐CSP has a nontrivial approximation algorithm whose performance ratio is better than that obtained by picking a random assignment to the variables. An intriguing question then is whether this is also the case for 2‐CSPs over larger, non‐Boolean domains. This question is still open, and is equivalent to whether the generalization of Max 2‐SAT to domains of size d, can be approximated to a factor better than (1 − 1/d2). In an attempt to make progress towards this question, in this paper we prove, first, that a slight restriction of this problem, namely, a generalization of linear inequations with two variables per constraint, is not approximation resistant, and, second, that the Not‐All‐Equal Sat problem over domain size d with three variables per constraint, is approximation resistant, for every d ≥ 3. In the Boolean case, Not‐All‐Equal Sat with three variables per constraint is equivalent to Max 2‐SAT and thus has a nontrivial approximation algorithm; for larger domain sizes, Max 2‐SAT can be reduced to Not‐All‐Equal Sat with three variables per constraint. Our approximation algorithm implies that a wide class of 2‐CSPs called regular 2‐CSPs can all be approximated beyond their random assignment threshold. © 2004 Wiley Periodicals, Inc. Random Struct. Alg. 2004
A behavioral type system and its application in Ptolemy II
Authors: Lee Edward A. , Xiong Yuhong 
Published: May 2004

Abstract.
Interface automata [deH01] have been introduced as an interface theory [deH01a] capable of functioning as a behavioral type system. Behavioral type systems describe dynamic properties of components and their compositions. Like traditional (data) type systems, behavioral type systems can be used to check compatibility of components. In this paper, we use interface automata to devise a behavioral type system for Ptolemy II, leveraging the contravariant and optimistic properties of interface automata to achieve behavioral subtyping and polymorphism. Ptolemy II is a software framework supporting concurrent component composition according to diverse models of computation. In this paper, we focus on representing the communication protocols used in component communication within the behavioral type system. In building this type system, we identify two key limitations in interface automata formalisms; we overcome these limitations with two extensions, transient states and projection automata. In addition to static type checking, we also propose to extend the use of interface automata to the on-line reflection of component states and to run-time type checking, which enable dynamic component creation, morphing application structure, and admission control. We discuss the trade-offs in the design of behavioral type systems.
The Political Thought of Sun Yat-sen: Development and Impact. By Audrey Wells. [London: Palgrave Macmillan, 2001. 256 pp. £50.00. ISBN 0-333-77787-5.]
Authors: Myers Ramon H. 
Published: May 2004

What, another book about Sun Yat-sen? The sceptical reader should not be deterred. He or she will learn much by reading this informative, lucid history of Sun Yat-sen's career, his thinking, and his influence on China as well as on various leaders of developing nations of the last century.Wells portrays Sun as a rare, humane revolutionary who could have unified China and facilitated China's transition to a peaceful, modern society and state. Such achievements were well in his grasp but the foreign leaders of Sun's time preferred a weak, divided China and ignored his pleas for assistance.Although Sun was famous in China immediately after his death, Sun's “synthesis of Eastern and Western ideas” attracted few outstanding Chinese leaders to his cause. As Ssu-yu Teng and John K. Fairbank stated in their China's Response to the West: A Documentary Survey, 1839–1923 (p. 276) “the doom of the Kuomintang was sealed from the time when Dr. Sun failed to convince the scholars of Peita that his “Three People's Principles” could give them intellectual leadership.” Why Sun's political thought did not attract a broad segment of the leading elite to agree with his message and follow his revolutionary path is still a puzzle.
Love-Letters and Privacy in Modern China: The Intimate Lives of Lu Xun and Xu Guangping. By Bonnie S. McDougall. [Oxford: Oxford University Press, 2002. 305 pp. $125.00. ISBN 0-19-925679-9.]
Authors: Chou Eva Shan 
Published: May 2004

This is an important work from a scholar who has already made wide-ranging contributions to our understanding of modern Chinese literature. With Love-Letters and Privacy in Modern China, Bonnie S. McDougall now adds a valuable study of its most prominent figure, Lu Xun (1881–1936), contributing in particular to the fast-growing scholarship on the private life of this modern icon. Her study focuses on his relationship with Xu Guangping (1898–1968), the student who became his partner, mother of his son, and for three decades after his death, editor and memoirist.Two wider aims, named in the title, are to examine love letters as a literary genre and privacy as a social variable. Such research performs the task of bringing Chinese data to issues of general concern. The matter is not just a territorial one. As the author says of investigating privacy in modern China, “privacy is a human rights issue: deny a sense of privacy . . . , or claim that it is substantially different, and we deny the people of that culture basic rights of association and communication” (p. 209).
Multilingualism in China: The Politics of Writing Reforms for Minority Languages 1949–2002. By Minglang Zhou. [Berlin and New York: Mouton de Gruyter, 2003. xxiv+458 pp. €94.00. ISBN 3-11-017896-6.]
Authors: Mackerras Colin 
Published: May 2004

This book is a detailed examination of reform in the writing of minority languages under the PRC, including the adaptation of languages to scripts never before used to write them. Considering how closely language is related to culture and society, this entails a good deal of treatment of issues such as PRC politics, external influences, such as from the Soviet Union and the West, the impact of modernization and factors like education and religion. Of course, there is quite a bit about China's spoken minority languages as well.The book is generally well written, though there are places where the language becomes dense and difficult to follow. The source material for the book is four summers of fieldwork in China's minority areas (1997–2000) and a vast amount of printed material. The list of references takes up no less than 40 pages (pp. 407–446). All items are in Chinese or English. The author makes judicious use of this array of material to mould his own viewpoints on specific issues.My only real problem with this book as a work of scholarship is the lack of clarity in the aims and central argument. The introduction gives extensive historical background on China's ethnic relations and policies, including in the PRC. It also forecasts the topics of the individual chapters, concluding with the author's hope that China's experiences in multilingualism will “facilitate the maintenance and development of minority languages in the world community” (p. 35). The conclusion summarizes answers to some of the crucial questions the book tackles, and again returns to the hope that the Chinese experience will be of use to the world as a whole.
Effect of Annealing and of Effect of Annealing and of Cooling Rates on n‐GaAs Electrode Photoelectrochemical Characteristics
Authors: Hilal Hikmat S. , Salih Subhi K. , Sa′adeddin Iyad A. , Campet Guy 
Published: May 2004

The effect of annealing of the n‐GaAs semiconductor on its characteristics in photoelectrochemical (PEC) systems
has been investigated. The photocurrent densities vs potential plots were improved by annealing. Cell efficiency and short‐circuit current densities were enhanced for the annealed n‐GaAs.The effect of the rate of cooling of heated n‐GaAs wafers was also investigated. It was found that the slowly cooled
electrodes gave better dark current density vs. potential plots, for samples annealed below 600ºC. For samples annealed at higher temperatures, quenching gave better dark‐current density vs potential plots. For n‐GaAs,
slowly cooled electrodes from temperatures below 600ºC showed better photocurrent densityvspotential plots and higher efficiency. n‐GaAs samples, quenched from temperatures above 700ºC, showed better photocurrent density vs potential plots and higher efficiency than their slowly cooled counterparts.