bluuebunny/crossref_metadata_2025 huggingface dataset:
Histology and ultrastructure of the gut epithelium of the neotenic cave salamander, Proteus anguinus (Amphibia, Caudata)
Authors: Bizjak Mali Lilijana , Bulog Boris
Published: December 2003

Histological, histochemical, and ultrastructural features of the gut of the European endemic cave salamander Proteus anguinus were studied. The gut is a relatively undifferentiated muscular tube lined with a simple columnar epithelium containing numerous goblet cells. The mucosa and underlying lamina propria/submucosa are elevated into a number of high longitudinal folds projecting into the lumen. The enterocytes are covered apically with uniform microvilli. Irregularity in the arrangement of microvilli was observed. Occasionally, irregular protrusions of the cytoplasm appear between groups of microvilli. Pinocytotic activity occurs at the bases of the intermicrovillous space. Mitochondria are numerous in the apical cytoplasm and basally beneath the nuclei. The supranuclear cytoplasm contains most of the cell organelles. The lateral plasma membranes of adjacent cells interdigitate and are joined by junctional complexes. The periodic acid‐Schiff (PAS) reaction, indicating neutral mucosubstances, is positive only in the apical brush border of enterocytes and in goblet cells. The goblet cells also stained with Alcian blue (AB), at pH 2.5, thus revealing the presence of carboxylated glycosaminoglycans. Compact aggregations of AB‐ and PAS‐negative cells are situated directly below the epithelium. Mitotic figures are present in individual clusters of cells. The fine structure of cells in these clusters indicated that these cells could be responsible for renewal of intestinal epithelium. Numerous endocrine‐like cells could also be seen. The closely packed smooth muscle cells and amorphous extracellular material with collagen fibrils constitute a net‐like structure under the basal lamina that is very closely associated with the epithelium. There are numerous acidophilic granular cells between epithelial cells, in the lamina propria/submucosa, and between cells aggregations. They seem to be associated with nematode infections and possibly constitute a humoral defense mechanism. J. Morphol. 259:82–89, 2004. © 2003 Wiley‐Liss, Inc.
Morphogenesis of parrot jaw muscles: Understanding the development of an evolutionary novelty
Authors: Tokita Masayoshi
Published: December 2003

Parrots have developed novel head structures in their evolutionary history. The appearance of two new muscles for strong jaw adduction is especially fascinating in developmental and evolutionary contexts. However, jaw muscle development of parrots has not been described, despite its uniqueness. This report first presents the normal developmental stages of the cockatiel (Nymphicus hollandicus), comparable to that of the chick. Next, the peculiar skeletal myogenesis in the first visceral arch of parrots is described, mainly focusing on the development of two new jaw muscles. One of the parrot‐specific muscles, M. ethmomandibularis, was initially detected at Nymphicus Stage 28 (N28) as the rostral budding of M. pterygoideus. After N32, the muscle significantly elongates rostrodorsally toward the interorbital septum, following a course lateral to the palatine bone. Another parrot‐specific muscle, M. pseudomasseter, was first recognized at N36. The muscle branches off from the posteromedial M. adductor mandibulae externus and grows in a dorsolateral direction, almost covering the lateral surface of the jugal bar. The upper tip of the muscle is accompanied by condensed mesenchyme, which seems to be derived from cephalic neural crest cells. J. Morphol. 259:69–81, 2004. © 2003 Wiley‐Liss, Inc.
On the nonlinear isoconversional procedures to evaluate the activation energy of nonisothermal reactions in solids
Authors: Budrugeac P. , Segal E.
Published: December 2003

A general procedure for deriving the equations that underlie various isoconversional nonlinear methods for evaluating the activation energy is presented. A new integral isoconversional nonlinear method with integration over a given range of conversion is suggested. This method was applied to simulated nonisothermal data as well as to data for the nonisothermal decomposition of ammonium perchlorate. The obtained dependencies of the activation energy on the degree of conversion were compared with those resulting from other nonlinear and linear methods of analysis. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 36: 87–93 2004
A new approach to response surface development for detailed gas‐phase and surface reaction kinetic model optimization
Authors: Davis Scott G. , Mhadeshwar Ashish B. , Vlachos Dionisios G. , Wang Hai
Published: December 2003

We propose a new method for constructing kinetic response surfaces used in the development and optimization of gas‐phase and surface reaction kinetic models. The method, termed as the sensitivity analysis based (SAB) method, is based on a multivariate Taylor expansion of model response with respect to model parameters, neglecting terms higher than the second order. The expansion coefficients are obtained by a first‐order local sensitivity analysis. Tests are made for gas‐phase combustion reaction models. The results show that the response surface obtained with the SAB method is as accurate as the factorial design method traditionally used in reaction model optimization. The SAB method, however, presents significant computational savings compared to factorial design. The effect of including the partial and full third order terms was also examined and discussed. The SAB method is applied to optimization of a relatively complex surface reaction mechanism where large uncertainty in rate parameters exists. The example chosen is laser‐induced fluorescence signal of OH desorption from a platinum foil in the water/oxygen reaction at low pressures. We introduce an iterative solution mapping and optimization approach for improved accuracy. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 36: 94–106, 2004
Characterizing complex reaction mechanisms using machine learning clustering techniques
Authors: Blurock Edward S.
Published: December 2003

A machine learning conceptual clustering method applied to reaction mechanisms provides an automatic and, hence, unbiased means to differentiate between reactive phases within a total reactive process. Similar reactive phases were defined by means of local reaction sensitivity values. The method was applied to the Hochgreb and Dryer aldehyde combustion mechanism of 36 reactions. Three major time ranges were found and characterized: an initial phase of aldehyde reaction, an intermediate phase where only a small amount of aldehyde is left, and an end phase of reactions to final products. Further refinements of these phases into subtime intervals were found. All ranges found could be chemically justified. This method is meant as a supplement to existing methods of mechanism analysis and its main purpose is the automatic characterization of existing mechanisms and can potentially be used for mechanism reduction. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 36: 107–118, 2004
Mechanistic disparity in the electron transfer reactions of thiosulfate with di‐μ‐oxo‐bis(1,4,8,11‐tetraazacyclotetradecane)‐dimanganese(III,IV) and di‐μ‐oxo‐bis(1,4,7,10‐tetraazacyclododecane)‐dimanganese(III,IV) complexes
Authors: Panja Anangamohan , Shaikh Nizamuddin , Banerjee Pradyot , Saha Basudeb
Published: December 2003

A comparative kinetic study of the reactions of two mixed valence manganese(III,IV) complexes of macrocyclic ligands, [L1MnIV(O)2MnIIIL1], 1 (L1 = 1,4,8,11‐tetraazacyclotetradecane) and [L2MnIV(O)2MnIIIL2], 2 (L2 = 1,4,7,10‐tetraazacyclododecane) with thiosulfate has been carried out by spectrophotometry in aqueous buffer at 30°C. Reaction between complex 1 and thiosulfate follows a first‐order rate saturation kinetics. The pH dependency and kinetic evidences suggest the participation of two complex species of MnIII(μ‐O)2MnIV under the experimental conditions. Detailed kinetic study shows that reduction of 2 proceeds through an autocatalytic path where the intermediate (MnIII)2 species has been assumed to catalyze the reaction. The difference in the reaction mechanisms is ascribed to the difference in stability of the intermediate complex species, the evidence for which comes from the electrochemical behavior of the complexes and time dependent EPR spectroscopic measurements during the reduction of 2. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 36: 119–128, 2004
A comparative kinetic study for the oxidation of 2‐mercaptoethanol by di‐μ‐oxo‐bis(1,4,7,10‐tetraazacyclododecane)‐dimanganese(III,IV) and di‐μ‐oxo‐bis(1,4,8,11‐tetraazacyclotetradecane)‐dimanganese(III,IV) complexes: Influence of copper(II)
Authors: Goswami Sanchita , Shaikh Nizamuddin , Panja Anangamohan , Banerjee Pradyot
Published: December 2003

A comparative kinetic study of the reactions of two mixed valence manganese(III,IV) complexes with macrocyclic ligands, [L1MnIV(O)2MnIIIL1], 1 (L1 = 1,4,7,10‐tetraazacyclododecane) and [L2MnIV(O)2MnIIIL2], 2 (L2 = 1,4,8,11‐tetraazacyclotetradecane) with 2‐mercaptoethanol (RSH) has been carried out by spectrophotometry in aqueous buffer at (30 ± 0.1)°C. Rate of the reactions between the oxidants and the reductant was found to be negligibly slow with no systematic dependence on either redox partners. Externally added copper(II) (usually 5 × 10−7 mol dm−3), however, increases the rate of the reduction of 1 and 2 significantly. In the presence of catalytic amount of copper(II), the rate of the reaction is nearly proportional to [RSH] at lower concentration of the reductant but follows a saturation kinetics at higher concentration of the latter for the reaction between 1 and the thiol. Reaction rate was found to be strongly influenced by the variation of acidity of the medium and the observed kinetics suggests that the two reductant species ([Cu(RSH)]2+ and [Cu(RS)]+) are significant for the reaction between 1 and the thiol. The dependence of the rate on [RSH] for the reduction of 2 by the thiol was complex and rationalized considering two equilibria involving the catalyst (Cu2+) and the reductant. The pH rate profile suggests that both the μ‐O protonated [MnIII(O)(OH)MnIV] and the deprotonated [MnIII(O)2MnIV] forms of the oxidant 2 become important. The kinetic results presented in this study indicate the domination of outer‐sphere path. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 36: 129–137, 2004
Parametric sensitivities for optimal control problems using automatic differentiation
Authors: Griesse Roland , Walther Andrea
Published: December 2003

This article presents a new area of application for Automatic Differentiation (AD): Computing parametric sensitivities for optimization problems. For an optimization problem containing parameters which are not among the optimization variables, the term parametric sensitivity refers to the derivative of an optimal solution with respect to the parameters. We treat non‐linear finite‐ and infinite‐dimensional optimization problems, in particular optimal control problems involving ordinary differential equations with control and state constraints, and compute their parametric sensitivities using AD. Particular attention is given to the generation of second‐order derivatives required in the process. Copyright © 2003 John Wiley & Sons, Ltd.
Four inventory models for deteriorating items with time varying demand and partial backlogging: A cost comparison
Authors: Skouri K. , Papachristos S.
Published: December 2003

In this paper we present four inventory control models under the following assumptions. Planning horizon is finite and demand is a general logconcave function of time. The models allow for deterioration of items over time and shortages partially backlogged at an exponential rate. For each of the models we establish the existence of a unique optimal policy. We then compute their optimal costs and rank them according to cost performance. This ranking indicates that model four gives the lowest cost. Numerical examples are given to support the theoretical findings and explain the application of procedures. Copyright © 2003 John Wiley & Sons, Ltd.
Application of LQ modelling and optimization in urban traffic control
Authors: Selekwa Majura F. , Mussa Renatus N. , Chiteshe Able
Published: December 2003

The increasing congestion on urban streets demands traffic control signal timing to be well co‐ordinated and optimized even during the transition between timing patterns used in different periods of time‐of‐day (TOD). The TOD timing plans, defined by fixed‐time co‐ordination parameters, need to change from one TOD period to another. The current methods used in transitioning are aimed at achieving quick transition rather than optimizing traffic flow during the transition period. As a result, they generally cause increased vehicle delays during the transition period particularly for vehicles on the minor street, which face lengthened red times.

This paper proposes a quadratic optimization method that can be used to reduce disutility measures to motorists during the transition period. The transition is modeled as a linear dynamic process, and the disutility measures are modeled as the sum of squares of the deviations of the co‐ordination parameters—that is, cycle length, phase split, and offset—from the optimal values during the transition. A linear quadratic (LQ) optimization technique of optimal control is used to determine the step size and the number of steps necessary to complete the transition with minimum disutility. The proposed transition period optimization method has the advantage that the user need not specify minimum and maximum cycle length to achieve optimization, as is the case with current methods.

Simulation results for three co‐ordinated intersections showed that the proposed method reduces total vehicle delay when compared to the ‘immediate’ transition method embedded in CORSIM traffic simulation software. This is due to the fact that vehicles on the minor street approaches get proportional green time without significantly affecting green times on the major street approach green phase. However, the method showed a slight increase in total delay for vehicles on the major street. Copyright © 2003 John Wiley & Sons, Ltd.
The discovery and progress of MgCl2‐supported TiCl4 catalysts
Authors: Kashiwa Norio
Published: December 2003

Polyolefins represented by polyethylene (PE) and polypropylene (PP) are indispensable materials in our daily lives. TiCl3 catalysts, established by Ziegler and Natta in the 1950s, led to the births of the polyolefin industries. However, the activities and stereospecificities of the TiCl3 catalysts were so low that steps for removing catalyst residues and low stereoregular PP were needed in the production of PE and PP. Our discovery of MgCl2‐supported TiCl4 catalysts led to more than 100 times higher activities and extremely high stereospecificities, which enabled us to dispense with the steps for the removals, meaning the process innovation. Furthermore, they narrowed the molecular weight and composition distributions of PE and PP, enabling us to control the polymer structures precisely and create such new products as very low density PE or heat‐sealable film at low temperature. The typical example of the product innovations by the combination of the high stereospecificity and the narrowed composition distribution is high‐performance impact copolymer used for an automobile bumper that used to be made of metal. These process and product innovations established these polyolefin industries. The latest MgCl2‐supported TiCl4 catalyst is very close to perfect control of isotactic PP structure and is expected to bring about further innovations. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1–8, 2004
Estimation of monomer reactivity ratios in free‐radical solution copolymerization of lauryl methacrylate–isobutyl methacrylate
Authors: Habibi A. , Vasheghani‐Farahani E. , Semsarzadeh M. A. , Sadaghiani K.
Published: December 2003

Copolymers of isobutyl methacrylate (i‐BMA) and lauryl methacrylate (LMA) were prepared by free‐radical solution copolymerizations at 70 °C with azobisisobutyronitrile (AIBN) as an initiator. The synthesis of these copolymers was investigated over a wide composition range both at low and high conversion levels. Copolymer compositions were determined from the %C, %H, and %O contents of copolymer by elemental analysis. Monomer reactivity ratios were estimated by analyzing composition data with nonlinear least‐squares (NLLS) models based on Marquardt optimization and van Herk methods. The point estimates, 95% individual confidence intervals and 95% joint confidence intervals are obtained from differential and integral approaches. Even though no explicit integral form for penultimate unit model (PUM) is available, a numerical approach is developed for integral estimation of reactivity ratios from PUM. A simulator program was developed which upon coupling of experimental data, NLLS analysis, and D‐optimal criteria calculates the best optimized values of monomer reactivity ratios and monomer feed compositions in a sequential and iterative order for terminal and penultimate unit models. Moreover, the simulator has the capibilities to calculate all features of van Herk method, maximum compositional drift in each monomer feed composition, and data reconciliation. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 112–129, 2004
Infrared and Raman spectroscopic investigation of crosslinked polystyrenes and radiation‐grafted films
Authors: Brack H.‐P. , Fischer D. , Peter G. , Slaski M. , Scherer G. G.
Published: December 2003

The crosslinking of functionalized polystyrene resins is often of critical importance in determining resin properties and performance in the application of these materials as membranes and supports. In this investigation model systems are developed for quantifying the infrared and Raman spectroscopic properties of copolymers based on poly(styrene‐co‐divinylbenzene). Analytical curves appropriate for the quantification of para‐ and metasubstituted species and pendant double bonds are reported, and corrections to previously reported spectroscopic assignments and analytical methods are made. The usefulness of these two analytical methods in characterizing radiation‐grafted films and commercial copolymers is compared, and typical characterization results are given. The relative concentrations of the species found in the grafted films are quite different from their concentrations in the grafting solution, and empirical relationships between the two are developed. In addition, the graft composition varies as a function of the base polymer film thickness and type and the penetration depth in the grafted film. Radiation‐grafted films are more highly crosslinked in their near surface regions, and thinner films are more extensively crosslinked. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 59–75, 2004
Atom transfer radical polymerization of methyl methacrylate via reversibly supported catalysts on silica gel via self‐assembly
Authors: Ding Shijie , Yang Jun , Radosz Maciej , Shen Youqing
Published: December 2003

A reversible catalyst immobilization system via self‐assembly of hydrogen bonding between thymine anchored on silica gel support and 2,6‐diaminopyridine functionalized with a catalyst (copper bromide‐N,N,N′,N′‐tetraethyldiethylenetriamine (TEDETA) complex) was developed for the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA). At elevated temperatures, the hydrogen bonding disassociated and released the catalyst as free small molecules for catalysis, which effectively mediated a living polymerization of MMA, producing PMMA with controlled molecular weight and narrow molecular weight distribution (<1.3). At room temperature, the catalyst assembled on the silica gel support by hydrogen bonding, and thus could be recovered and reused for a second run of ATRP. The recovered catalyst still mediated a living polymerization of MMA with reduced activity (54–64%), but had much improved control of the polymerization. The resulting PMMA had molecular weights very close to theoretical vales. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 22–30, 2004
Supramolecular poly(ether ketone)–polyisobutylene pseudo‐block copolymers
Authors: Binder Wolfgang H. , Kunz Michael J. , Ingolic Elisabeth
Published: December 2003

The association behavior of telechelic hydrogen‐bonded poly(ether ketone) (PEK) and polyisobutylene (PIB) polymers and the formation of a new class of pseudo‐block copolymers is reported. The attachment of complementing hydrogen bonds (thymine/2,6‐diaminotriazine and cytosine/2,6‐diaminotriazine) onto the respective PIB and PEK polymers leads to a dramatic increase in the miscibility between the normally immiscible PEK and PIB polymers. The structure formation in the liquid state was studied by dynamic NMR spectroscopy as well as in the solid state via solid‐state NMR‐spectroscopy, DSC, and TEM methods. The polymers form a nanophase structure with a periodicity of 70 nm with the microphase separation occurring specifically within the donor–acceptor pair with the higher binding constant (thymine/2,6‐diaminotriazine) and not within the weaker bonded cytosine/2,6‐diaminotriazine pair. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 162–172, 2004
Alumina as support for metallocene catalyst in ethylene polymerization
Authors: de Fátima V. Marques Maria , de Alcantara Moacir
Published: December 2003

Aluminas thermally and/or chemically treated were used as support for Cp2ZrCl2 and evaluated in ethylene polymerization at constant reaction conditions. Two different calcination temperatures were employed, and the metallocene was fixed either directly or after support pretreatment with MAO, TMA, or NaOH solutions. The obtained alumina‐supported catalysts showed activities comparable to the homogeneous precursor. It was noticed that the textural properties of the supports strongly influenced the catalyst performance. The direct fixation of the metallocene on alumina produced catalysts presenting lower activities in comparison to the ones obtained from the chemically treated supports. The chemical pretreatment of hydrated alumina with TMA originated catalysts whose activities were superior to those obtained by pretreatment with MAO. The pretreatment with NaOH produced the more active catalyst and generated branched polymer. The molecular weight of the PE produced by the supported catalysts was higher than the ones obtained with the homogeneous system. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 9–21, 2004
Controlled radical polymerization of 2‐hydroxyethyl methacrylate initiated by photofunctional 2‐(N,N‐diethyldithiocarbamyl)isobutyric acid
Authors: Ishizu Koji , Khan Ruhul A. , Ohta Yoshihiro , Furo Masahito
Published: December 2003

We demonstrated that density functional theory calculations provide a reliable and quantitative prediction of the trends in CS bond dissociation energies using several model compounds as photoinitiator. On the basis of this information, we designed a possible photofunctional initiator for the polymerization of hydrophilic vinyl monomers. Photopolymerization of 2‐hydroxyethyl methacrylate (HEMA) hydrophilic monomer was carried out in ethanol initiated by 2‐(N,N‐diethyldithiocarbamyl)isobutyric acid (DTCA) under UV irradiation. We performed the first‐order time‐conversion plots in this polymerization system, and the straight line in the semilogarithmic coordinates indicated first order in monomer. The molecular weight of the poly(2‐hydroxyethyl methacrylate) (PHEMA) increased with increasing conversion. The molecular weight distribution (Mw/Mn) of the PHEMA was about 1.5. Methyl methacrylate (MMA) could also be polymerized in a living fashion with such a PHEMA precursor as a macroinitiator because PHEMA exhibited a dithiocarbamate (DC) group at its terminal end. This system could be applied to the architecture of amphiphilic block copolymers. It was concluded that these polymerization systems proceeded with controlled radical mechanism. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 76–82, 2004
Two‐stage copolycondensation of preformed oligomers with bisphenols by tosyl chloride/dimethylformamide/pyridine from distributions of resulting oligomers determined by a combination of gel permeation chromatography and NMR
Authors: Higashi Fukuji , Sugishita Kanako
Published: December 2003

A two‐stage co‐oligomerization of the oligomers initially formed from an equimolar mixture of isophthalic acid (IPA) and terephthalic acid (TPA) and 2,2‐bis(4‐hydroxyphenyl)propane (BPA, 50 mol %) with bisphenols (BPs, 20 mol %) was carried out using a tosyl chloride/dimethylformamide/pyridine condensing agent. The distributions of the resulting oligomers (nx‐mers), which were quenched with methanol, were determined by a combination of gel permeation chromatography (GPC) and NMR. These distributions (presented by molar percentage) were conveniently calculated with the equation nx (mol %) = nx (% mol by GPC) × n0 (mol % by NMR)/n0 (% mol by GPC), where nx (% mol) = nx (wt % by GPC)/its molecular weight. The results showed the distributions of the preformed IPA/TPA‐BPA oligomers to be in fairly good accord with those obtained directly from GPC and to be supported by the NMR results. The calculation was applied to the co‐oligomers prepared up to a reaction of 0.7, at which there was an increase in the number of higher oligomers indivisible by GPC and the distributions could no longer be determined by molar percentage. The calculated distributions are discussed in relation to the results of copolycondensation. The sequence distributions in the resulting co‐oligomers, which were also examined by NMR, are compared with those in the copolymers. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 44–51, 2004
Solid polymer electrolytes. VI. Microstructure of organic–inorganic hybrid networks composed of 3‐glycidoxypropyltrimethoxysilane and LiClO4 and affected by different synthetic routes
Authors: Liang Wuu‐Jyh , Kuo Ping‐Lin
Published: December 2003

Hybrid organic–inorganic materials derived from 3‐glycidoxypropyltrimethoxylsilane were prepared via two different synthetic routes: (1) the HCl‐catalyzed sol–gel approach of silane followed by the lithium perchlorate (LiClO4)/HCl‐catalyzed opening of epoxide and (2) the simultaneous gelation of tin/LiClO4‐catalyzed silane/epoxide groups. LiClO4 catalyzed the epoxide polymerization, and its effects on the structures of these hybrid materials were studied by NMR. The structure of the inorganic side was probed by solid‐state 29Si NMR spectroscopy, and the characterizations of the organic side and the chemical processes involved in the different synthetic routes were performed with solid‐state cross‐polarity/magic‐angle‐spinning 13C NMR. The different synthetic routes significantly affected the polymerization behaviors of the organic and inorganic sides in the presence of LiClO4. A larger amount of LiClO4 promoted the opening of epoxide and led to the formation of longer poly(ethylene oxide) chains via the HCl‐catalyzed sol–gel approach, whereas in the case of the tin‐catalyzed approach, the faster polymerization of the inorganic side hindered the growth of the organic network. The addition of LiClO4 was proven to be without crystalline salt present in the hybrid networks by wide‐angle X‐ray powder diffraction. Also, the interactions between the ions and hybrid host, examined with Fourier transform infrared and 7Li proton‐decoupled magic‐angle‐spinning NMR, further demonstrated that extensive ion aggregation existed in these hybrid materials. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 151–161, 2004
Anionic polymerization of methyl methacrylate initiated with lithium diphenylamide (Ph2NLi) in the presence of divalent transition metal halide
Authors: Ihara Eiji , Todaka Tsuyoshi , Inoue Kenzo
Published: December 2003

Anionic polymerization of methyl methacrylate (MMA) in the presence of divalent transition metal halide (MX2 = FeBr2, MnCl2, CoCl2, NiBr2) was investigated. Initiating systems with various combinations of MX2, lithium diphenylamide (Ph2NLi), and organolithium (RLi, where R = nBu, Me) were effective to giving a high yield of poly(methyl methacrylate)s (PMMAs) at −78 °C in toluene. The tacticity of the resulting PMMAs was highly dependent on the combination of the reagents used for the generation of the initiating systems within a syndiotactic (rr = 59%) to isotactic (mm = 65%) range. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 31–37, 2004
Nanoscopic confinement effects on ethylene polymerization by intercalated silicate with metallocene catalyst
Authors: Wang Qi , Zhou Zhiyin , Song Lixin , Xu Hong , Wang Li
Published: December 2003

In this article we report a study of in situ polymerization of ethylene by intercalated montmorillonite (MMT) with metallocene, allowing an investigation of the nanoscopic confinement effect of olefin polymerization and of the structure of polymer prepared in situ. Ethylene polymerization by intercalated MMT with metallocene and the varied aggregation morphology of the resulting polymer during polymerization were studied by X‐ray diffraction (XRD), differential scanning calorimetry (DSC), and gel permeation chromatography (GPC). The polymerization kinetics and the resulting polymer before and after destruction of the silicate registry were different. The laminated structure of silicate lowered the all‐reaction rate, including the propagation, chain transfer, and termination reactions, producing polymer of a high molecular weight. Moreover, the melting point of the polymer gradually increased during the in situ polymerization, indicating that nanoscopic confinement between solid surfaces affects the crystallization behavior of polyethylene via in situ polymerization. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 38–43, 2004
Copolymerization of ethylene or propylene with α‐olefins containing hydroxyl groups with zirconocene/methylaluminoxane catalyst
Authors: Hagihara Hideaki , Tsuchihara Kenji , Takeuchi Kazuhiko , Murata Masahide , Ozaki Hiroyuki , Shiono Takeshi
Published: December 2003

Copolymerization of olefins (ethylene and propylene) and 5‐hexen‐1‐ol pretreated with alkylaluminum was performed using [dimethysilylbis(9‐fluorenyl)]zirconium dichloride/methylaluminoxane as the catalyst. The copolymerization required extra addition of alkylaluminum to prevent deactivation of the catalyst when 5‐hexen‐1‐ol was pretreated with trimethylaluminum, whereas the triisobutylaluminum‐treated system did not require any addition of alkylaluminum. The molecular weight of the copolymer depended on the kind of alkylaluminum compound (masking reagent, additive, and cocatalyst). 13C NMR analysis proved that poly(ethylene‐co‐5‐hexen‐1‐ol) containing 50 mol % of 5‐hexen‐1‐ol acted as an alternating copolymer, whereas the poly(propylene‐co‐5‐hexen‐1‐ol) acted as a random copolymer. The surface property of the copolymers was simply evaluated by means of water drop contact angle measurement. It was found that the copolymers containing large amounts of 5‐hexen‐1‐ol units showed good hydrophilic properties. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 52–58, 2004
Synthesis of semiaromatic polyimides from aromatic diamines containing adamantyl units and alicyclic dianhydrides
Authors: Watanabe Yasufumi , Shibasaki Yuji , Ando Shinji , Ueda Mitsuru
Published: December 2003

We prepared new semiaromatic polyimides from alicyclic dianhydrides and aromatic diamines containing adamantyl and biadamantyl units. Polycondensations were performed in 1‐methyl‐2‐pyrrolidinone at room temperature for 7 h and then 80 °C for 23 h, giving poly(amic acid)s with inherent viscosities up to 0.58 dL/g. Poly(amic acid)s were converted to corresponding poly(imide)s by thermal treatment. Poly(imide)s showed relatively high thermal stability (5% weight loss around 450 °C) and low dielectric constants (2.69–2.79). © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 144–150, 2004
Synthesis and characterization of novel poly(amide‐imide)s containing 1,3‐diamino mesitylene moieties
Authors: Lee Choonkeun , Iyer N. Padmanabha , Min Kyungwook , Pak Heyungsuk , Han Haksoo
Published: December 2003

A series of poly(amide‐imide)s were prepared using a new monomer, 1,3‐bis(trimellitimido)‐2,4,6‐trimethyl benzene (BTB), with four different diamines: 1,4‐phenylene diamine (PDA), 2,4‐diamino mesitylene (DAM), 2,2′‐dimethyl‐4,4′‐diamino biphenyl (DMDB), and 2,2′‐bis(trifluoromethyl)‐4,4′‐diamino biphenyl (TFDB). They were prepared by the condensation method in N‐methyl‐2‐pyrrolidinone (NMP) solvent using triphenyl phosphate and pyridine as condensing agents. The synthesized poly(amide‐imide)s were characterized by Fourier transform infrared and 1H NMR techniques. Films were prepared and characterized using DSC, thermogravimetric analysis (TGA), a prism coupler, and a film dielectric property analyzer. DSC measurement showed that the glass‐transition temperatures of the polymers were in the range of 259–327 °C. TGA analysis showed 5% weight loss, in the range of 472–514 °C. The refractive index varied from 1.6004 to 1.6586 in the following increasing order: BTB‐TFBM < BTB‐DAM < BTB‐DMDB < BTB‐PDA. For the poly(amide‐imide) films, the birefringence varied in the range of 0.0319–0.0580, in the following increasing order: BTB‐DAM < BTB‐TFBM < BTB‐DMDB < BTB‐PDA. The capacitance method showed that the dielectric constant of poly(amide‐imide) varied with the diamine structure; no difference was found by the optical method. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 137–143, 2004
Synthesis of hydrophilic polymers in supercritical carbon dioxide in the presence of a siloxane‐based macromonomer surfactant: Heterogeneous polymerization of 1‐vinyl‐2 pyrrolidone
Authors: Galia Alessandro , Giaconia Alberto , Iaia Vincenzo , Filardo Giuseppe
Published: December 2003

Batch free radical polymerization of 1‐vinyl‐2‐pyrrolidone (VP) in supercritical carbon dioxide (scCO2) was studied in the presence of a reactive polysiloxane surfactant (PDMS‐mMA). Phase behavior investigation showed that when the initial concentration of the surface active macromonomer was higher than 2.5% w/w with respect to the monomer, the reaction mixture, in the absence of efficient stirring, was initially opaque to the visible light, and it slowly turned to an orange tint. Polymerization experiments carried out with surfactant concentration higher than the aforementioned value proceeded with a fast kinetics, and led to the formation of spherical nanoparticles with almost quantitative yields (higher than 98% with a reaction time lower than 70 min). The effect of the concentration of the surface active macromonomer, the initiator and the monomer, and of the density of the fluid phase on the kinetics of the process and on the morphology of the particles was investigated. A marked decrease of the number‐average diameter of the polymer particles with the surfactant concentration was obtained without any particle agglomeration. A dependence on [Initiator]−0.16 of the particle diameter was observed. Such scaling law exhibits an exponent higher than any previously reported for dispersion processes and rather close to those foreseeable on the basis of Smith–Harkins kinetics for emulsion polymerization. Collected experimental results strongly suggest that the polymerization of VP in the presence of PDMS‐mMA could proceed with a nucleation mechanism different from that postulated in pure dispersion polymerization stabilized by graft‐forming surfactants. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 173–185, 2004
New fluorinated thermoplastic elastomers. II. Synthesis and characterization of perfectly alternating fluorinated polyimide–fluorinated polyhybridsiloxane block copolymers via polyhydrosilylation
Authors: Andre S. , Guida‐Pietrasanta F. , Rousseau A. , Boutevin B. , Caporiccio G.
Published: December 2003

The synthesis of perfectly alternating fluorinated polyimide–fluorinated polyhybridsiloxane block copolymers (FPI‐FPHSX) was achieved through polyhydrosilylation of α,ω‐diallylfluorinated polyimides (AT‐FPI) and α,ω‐dihydrosilane fluorinated–polyhybridsiloxanes (HT‐FPHSX). A series of three FPI‐FPHSX containing 15, 38, and 56 wt % of polyimide was synthesized and characterized by tuning the number‐average molecular weight either of the hard polyimide segments or of the soft polyhybridsiloxane segments. The influence of the soft and hard segment lengths on the behavior of the thermoplastic elastomer material was studied (hardness, surface tension, thermal stability). The FPI‐FPHSX block copolymers thermomechanical properties are also reported. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 200–207, 2004
Synthesis of C60‐containing polyphosphazenes from a new reactive macromolecular intermediate: Polyphophazene azides
Authors: Li Zhen , Qin Jingui
Published: December 2003

A novel synthetic strategy was developed to prepare polyphosphazenes containing C60 moieties as side chains. Thus, a new reactive macromolecular intermediate, polyphosphazene azides (P1), was obtained from poly(dichlorophosphazene) by the direct nucleophilic substitution reaction. Then the azide group in P1 reacted with C60 molecules to afford the first example of C60‐containing polyphosphazenes (P2 and P3). The polymers are soluble in common organic solvents. Molecular structural characterization for the polymers was presented by 1H NMR, 13C NMR, IR, ultraviolet–visible spectra, and gel permeation chromatography. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 194–199, 2004
Oligomeric calix[4]arene‐thiacrown ether for toxic heavy metals
Authors: Tabakci Mustafa , Memon Shahabuddin , Yilmaz Mustafa , Roundhill D. Max
Published: December 2003

A new oligomeric calix[4]arene‐thiacrown‐4 (5) was synthesized via a condensation reaction of 5,11,17,23‐tetra‐tert‐butyl‐25,27‐bis‐(4‐aminobenzyloxy)‐calix[4]arene‐thiacrown‐4 (4) with adipoyl dichloride. In this oligomerization reaction only five/six calix[4]arene‐thiacrown‐4 units were linked in the oligomeric chain. The complexation studies of 5 were made with liquid–liquid‐ extraction and solid–liquid‐sorption procedures. For comparison, the extraction efficiencies of monomers 1, 3, and 4 to selected transition metals are reported. The selectivity of monomers 3 and 4 toward Cu2+, Hg2+, and Pb2+ was lost after oligomerization in the two‐phase extraction systems. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 186–193, 2004
Distribution of melamine in polyester–melamine surface coatings cured under nonisothermal conditions
Authors: Gamage N. J. W. , Hill D. J. T. , Lukey C. A. , Pomery P. J.
Published: December 2003

The influence of experimental cure parameters on the diffusion of reactive species in polyester–melamine thermoset coatings during curing has been investigated with X‐ray photoelectron spectroscopy and attenuated total reflectance Fourier transform infrared. The diffusion of melamine plays a vital role in the curing process and, therefore, in the ultimate properties of coatings. At a low (<20%) hexamethoxymethylmelamine (HMMM) crosslinker concentration, the matrix composition is uniform, but at high HMMM concentrations, excess HMMM rapidly segregates to the air–coating interface. The rate of migration is governed by the difference in the surface free energies of polyester and HMMM and the concentration gradient of HMMM between the bulk and the surface. An increased rate of energy absorption also increases the rate of migration of HMMM to the surface. A physical model has been proposed to explain this surface segregation phenomenon in terms of cocondensation and self‐condensation reactions. It suggests that an appropriate amount of melamine can be segregated on the surface and allowed to self‐condense to form a desired thickness of a melamine topcoat through the control of the binder composition and cure conditions. This technique can be implemented to apply a melamine topcoat during cure. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 83–91, 2004
Synthesis and metal complexation of dihydroxyphosphino‐functionalized crosslinked styrene/maleic anhydride copolymers
Authors: McClain Aliecia R. , Hsieh You‐Lo
Published: December 2003

Crosslinked styrene (St)/maleic anhydride (MA) copolymers were synthesized, hydrolyzed with dicarboxylic acid, and converted to bear dihydroxyphosphino functionalities. The St–MA copolymers were prepared by azobisisobutyronitrile‐initiated polymerization in toluene at 90 °C in the presence of 2, 10, or 20% divinylbenzene crosslinker. The MA moiety was hydrolyzed into dicarboxylic acid to improve the hydrophilicity of the copolymers. The phenyl ring of St was phosphorylated with phosphorus trichloride in the presence of aluminum chloride and then hydrolyzed and oxidized with nitric acid at room temperature. The structures of the hydrolyzed and dihydroxyphosphino‐functionalized copolymers were confirmed by Fourier transform infrared spectroscopy and elemental analysis. The complexation behavior of these functionalized copolymers toward metal ions in 25 ppm aqueous solutions was observed over time periods of up to 7 h. The adsorption toward Pb(+2) was highest, followed by those of Cu(+2), Cr(+3), and Ni(+2). On the dihydroxyphosphino‐functionalized St–MA (20% divinylbenzene) copolymer, the adsorption of Pb(+2) showed a linear relationship with the concentrations and fit the Langmuir isotherm. The kinetics of Pb(+2) adsorption on this dihydroxyphosphino‐functionalized copolymer also fit the rate equation of the moving boundary model, t = [1 − 3(1 − X)2/3 + 2(1 − X)], where X is the fractional conversion. The metal‐ion adsorption kinetics of this copolymer appeared to be particle diffusion control, in which the moving boundary advanced from the surface toward the center. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 92–101, 2004
Free‐radical copolymerization of styrene with butyl acrylate. II. Elemental kinetic copolymerization step predictions from homopolymerization data
Authors: Fernández‐García M. , Fernández‐Sanz M. , Madruga E. L.
Published: December 2003

The free‐radical copolymerization of styrene and butyl acrylate has been carried out in benzene at 50 °C. The lumped kp/k parameter (where kp and kt are the average copolymerization propagation and termination rate constants, respectively) has been determined. Applying the implicit penultimate unit model for the overall copolymerization propagation rate coefficient and the terminal unit effect for the overall copolymerization termination rate coefficient and using the homopolymerization kinetic coefficients, we have found good qualitative agreement between the experimental and theoretical kp/k values. The variation of the copolymerization rate in solution with respect to the values previously found in bulk has been ascribed to a chain length effect on the copolymerization termination rate coefficient. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 130–136, 2004
Transetherification polycondensation: The roles of the catalyst, monomer structure, and polymerization conditions
Authors: Ch. Behera Girish , Ramakrishnan S.
Published: December 2003

A detailed study of the novel melt transetherification polycondensation process, which was recently developed in our laboratory, is presented. The efficacy of different catalysts, such as p‐toluenesulfonic acid (PTSA), camphorsulfonic acid, and their pyridinium salts, was examined. The pyridinium salts, especially pyridinium camphorsulfonate (PCS), outperformed PTSA both in terms of the polymer molecular weights (the polydispersity) and the extent of discoloration of the polymer. The evolution of the molecular weight with the polymerization time was monitored with two different catalysts, PTSA and PCS, and these studies demonstrated that, while PTSA yielded polymers with a broad molecular weight distribution, the use of PCS curtailed possible side reactions that led to this broadening. Model reactions suggested that one possible reason for this broadening could be the formation of macrocyclics facilitated by an ether–ether exchange reaction, which was shown to occur much more rapidly when PTSA was used. A further interesting and rather unprecedented feature, which became apparent while the effect of the acid–catalyst concentration was being examined, was the dual role played by the acid, which acted both beneficially as a catalyst and detrimentally, defunctionalizing the chain end and terminating polymer growth. This conclusion was based on the observed decrease in the molecular weight of the polymer at very high catalyst concentrations, which suggested that there existed an optimum catalyst concentration at which a balance was struck between the molecular weight of the polymer formed and the polymerization time. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 102–111, 2004
Z. Guan, Control of polymer topology through late‐transition‐metal catalysis, J Polym Sci Part A: Polym Chem (2003), 41(22), 3680–3692
Authors: Guan Zhibin
Published: December 2003

The original article to which this Erratum refers was published in
J Polym Sci Part A: Polym Chem (2003) 41(22) 3680–3692

No abstratct.
Combined Uvulopalatopharyngoplasty and Radiofrequency Tongue Base Reduction for Treatment of Obstructive Sleep Apnea/Hypopnea Syndrome
Authors: Friedman Michael , Ibrahim Hani , Lee George , Joseph Ninos J.
Published: December 2003

OBJECTIVE

In this study, we compare the objective results of uvulopalatopharyngoplasty (UPPP) combined with tongue base radiofrequency reduction (TBRF) with standard UPPP treatment of obstructive sleep apnea/hypopnea syndrome (OSAHS).

STUDYDESIGN

We conducted a retrospective study of 277 patients who had stage I, II, or III OSAHS based on the Friedman staging system previously presented.

METHODS

One hundred thirty‐four patients who had treatment with UPPP only were used as a control group. This included 31 patients with stage I, 29 patients with stage II, and 74 patients with stage III OSAHS. An additional 143 patients with Stage II (n = 52) and III (n = 91) OSAHS were treated with combined UPPP and TBRF, initially and followed by additional TBRF treatments (up to 9000 J) as necessary. Subjective results were collected based on questionnaires and the Epworth Sleepiness Scale score for the experimental group, but these subjective measures were not available for the control group. Objective results were compared based on the polysomnographic findings before and after surgery.

RESULTS

Subjectively, the study group did extremely well. Based on objective measures of successful treatment, UPPP plus TBRF resulted in a significantly higher percentage of patients who were “cured” of OSAHS compared with the control group.

CONCLUSIONS

Stage I patients were usually successfully treated with UPPP only. However, patients allocated to stage II or III will benefit from the addition of TBRF to standard UPPP. Many UPPP‐plus‐TBRF patients in this study aborted further recommended TBRF treatments after subjective improvement and therefore objective results for this group, although improved in comparison to stage II and III patients treated with UPPP only, may not represent maximal potential improvement.