bluuebunny/crossref_metadata_2025 huggingface dataset:
Benzoyl peroxide oxidation route to polyaniline salts—Part I
Authors: Palaniappan S.
Published: March 2004

Aniline was oxidized to polyaniline salt using benzoyl peroxide as an oxidizing agent in the presence of acids such as sulfuric, nitric, or hydrochloric acid by aqueous polymerization pathway. Polyaniline salts, their corresponding bases and redoped polyaniline salts were characterized by infrared, electronic absorption, x‐ray diffraction spectral techniques, elemental analysis and conductivity measurement. The result of this study indicates that both acid and surfactant group are present in the polyaniline salt as dopants. Polyaniline salts with reasonable yield (around 80%) and conductivity (0.04 S/cm) were prepared. Copyright © 2004 John Wiley & Sons, Ltd.
Litigation and the diabetic foot
Authors: Bending JJ , Foster AVM
Published: March 2004

A large number of patients with diabetes are managed in the community and this situation is likely to continue and the numbers increase. People with diabetes face a greatly increased risk of amputation – an event which may be followed by anger directed at those health professionals involved, among whom community podiatrists appear especially at risk of blame. The reasons for this, the issues which need to be addressed and the ways in which patients can be helped to come to terms with such a catastrophe are discussed. People with diabetes foot problems require multidisciplinary specialist team care. It is unacceptable for high‐risk diabetic patients to be treated in isolation. We suggest clear referral guidelines and care pathways which should be developed, understood and followed by each primary care trust. Copyright © 2004 John Wiley & Sons, Ltd.
Treading with care: foot care, litigation and the expert witness
Authors: Foster JAS
Published: March 2004

This is a practical introduction to acting as an expert witness. The expert's report is an integral part of all litigation concerning allegations of professional negligence. A well‐written report, embodying principles of sound academic research, is less likely to be challenged in court than a badly‐prepared one. An expert should not hesitate to question his terms of reference if they are unclear or require widening. It is crucial to remember that the report is written for the benefit of the court, not the instructing party. In the witness box, the oath to tell the truth, the whole truth and nothing but the truth is paramount. It should be assumed that the Judge can grasp difficult medical concepts but may require fuller explanation than a fellow medical practitioner. It is important to answer the question that has been asked – but it is in order to disagree with a false premise. Appropriate concessions are more likely to impress the court than posturing. Each question should be treated on its merits.

In conclusion, the role of the expert witness is demanding but application of these principles should make it a less daunting experience. Copyright © 2004 John Wiley & Sons, Ltd.
Fatal necrotising fasciitis after PEG insertion in a patient with diabetes
Authors: Kumar R , Fisher M
Published: March 2004

Percutaneous endoscopic gastrostomy (PEG) is the preferred method of long‐term enteral feeding in patients with a functioning gastrointestinal tract who cannot take food by mouth and have a reasonably long life expectancy. It is generally a safe procedure associated with a low morbidity and mortality and can be performed relatively easily with a low complication rate. We present the case of a 46‐year‐old lady with a long history of poorly controlled complicated diabetes who developed fatal necrotising fasciitis as a complication of PEG insertion. Necrotising fasciitis is a serious infection of soft tissues, which is caused by a mixed growth of aerobic and anaerobic organisms and carries a high mortality. The infection is particularly common in patients with diabetes. Copyright © 2004 John Wiley & Sons, Ltd.
Optimized conditions for the grafting reaction of poly(methyl acrylate) onto rubberwood fiber
Authors: Abu‐Ilaiwi Faraj A , Ahmad Mansor B , Ibrahim Nor Azowa , Ab Rahman Mohamad Zaki , Dahlan Khairul Zaman Md , Zin Wan Yunus Wan Md
Published: March 2004

Graft copolymerization of poly(methyl acrylate) (PMA) onto rubberwood fiber (RWF) was carried out by free radical initiation. Hydrogen peroxide and ferrous ions were used as an initiator system. Effects of various parameters (reaction temperature and reaction time, as well as hydrogen peroxide, ferrous ammonium sulfate and monomer concentrations) on the grafting percentage were investigated. A high percentage of grafting was achieved when optimum reaction conditions were used. The optimum temperature of the reaction was determined to be about 55 °C and the reaction time was 120 min. The optimum concentration of H2O2 was 0.03 M and the amounts of Fe2+ and MA were 0.4 mmol and 0.05 mol, respectively. The PMA homopolymer was removed from the graft copolymer by Soxhlet extraction using acetone. The presence of PMA on the fiber was confirmed by FT‐IR spectroscopy and gravimetry. The surface morphology of the poly(methyl acrylate)‐graft‐(rubberwood fiber) was studied by means of scanning electron microscopy. Copyright © 2004 Society of Chemical Industry
A processing‐induced clay dispersion and its effect on the structure and properties of polyamide 6
Authors: Liu Tianxi , Tjiu Wuiwui Chauhari , He Chaobin , Na Siew Siew , Chung Tai‐Shung
Published: March 2004

The nanostructures and morphologies of polyamide 6 (PA6)/organoclay nanocomposites prepared by melt compounding have been studied by using X‐ray diffraction (XRD) and transmission electron microscopy (TEM). A combination of XRD and TEM indicates that an exfoliated clay morphology dominates at low clay loadings (≤5 wt%) and a mixture of intercalated and exfoliated structures exists at high clay concentrations. It is worth noting, however, that optical microscopy (OM) even shows the presence of large clay agglomerates in samples with higher clay contents. OM images further present an overview of an uneven clay distribution due to the effect of injection molding. The crystalline structure of PA6 is greatly affected by this unevenness in the processing‐induced clay dispersion, as evidenced by differential scanning calorimetry (DSC). The thermal dynamic and mechanical properties of PA6 and the nanocomposites have been investigated as a function of clay concentration. The tensile tests show that the degree of dispersion of the nanoclay within the polymer matrix plays a vital role in property improvement. Copyright © 2004 Society of Chemical Industry
Diffusion of a carbonate mixture in a poly(vinyl alcohol‐co‐vinyl acetate) in the solid state
Authors: Becquart Frédéric , Taha Mohamed , Zerroukhi Amar , Kaczun Jürgen , Stebani Uwe
Published: March 2004

The diffusion study of a carbonate mixture composed of ethylene and propylene carbonates in poly(vinyl alcohol‐co‐vinyl acetate) (PVA–Ac) was studied. The diffusion occurred in the solid state and the effect of the carbonate mixture on the PVA–Ac properties are presented as well as the homogeneity of the diffusion. Due to the complexity of the diffusion kinetics with temperature, a model was made using the free volume theory at 75 °C. This temperature was chosen for modelling because the physical properties of the polymer are relatively stable at this point. Swelling heterogeneity, due to the particle size distribution of the powder, were estimated. Copyright © 2004 Society of Chemical Industry
Synthesis and characterization of amphiphilic graft copolymers with poly(ethylene glycol) and cholesterol side chains
Authors: Chern Chorng‐Shyan , Chiu Hsin‐Cheng , Chuang Yi‐Ching
Published: March 2004

Amphiphilic graft copolymers comprising monomeric units of methoxy poly(ethylene glycol) (mPEG)‐acrylate, 2‐hydroxyethyl methacrylate (HEMA)–cholesterol conjugates and HEMA were synthesized and their properties characterized. The value of the critical micelle concentration (CMC) for these copolymers is linearly proportional to the ratio of the number of mPEG–acrylates to that of the HEMA–cholesterol conjugates per macromolecule (NPEG/Nc), which is the most important parameter which influences the formation of polymeric micelles. The latter show excellent colloidal stability and their sizes decrease with increasing CMC. Based on the quenching of pyrene fluorescence, the relatively high levels of the loading capacity of pyrene are attributed to the elevated hydrophobicity of the micelle core. The loading capacity of pyrene decreases with increasing CMC. The weight‐average partition coefficient for pyrene in polymeric micelles increases with increasing polymer concentration because more micelles are available for accommodating pyrene. Copyright © 2004 Society of Chemical Industry
Surface modification of calcium carbonates studied by inverse gas chromatography and the effect on mechanical properties of filled polypropylene
Authors: Price Gareth J , Ansari Deeba M
Published: March 2004

Inverse gas chromatography (IGC) has been used to characterize the surfaces of a pure calcitic calcium carbonate as well as samples that had been treated with sodium polyacrylate and/or stearic acid. The dispersive components of the surface free energy for the pure material agreed well with related literature data. Polar contributions to the surface interactions with a range of probes were determined. The results show that the surface treatments reduced the polarities of the surfaces and that modification with stearic acid produced a non‐polar, low‐energy surface. Some mechanical properties of the polypropylene composites containing the modified calcium carbonates were found to correlate well with the filler surface energies. Copyright © 2004 Society of Chemical Industry
Performance of an intumescent‐flame‐retardant master batch synthesized by twin‐screw reactive extrusion: effect of the polypropylene carrier resin
Authors: Wang Qi , Chen Yinghong , Liu Yuan , Yin Huan , Aelmans Nico , Kierkels Rene
Published: March 2004

A novel way of preparing an intumescent flame retardant (IFR) and its master batch by the reactive extrusion of melamine phosphate and pentaerythritol, together with a polypropylene (PP) carrier, in a twin‐screw extruder has been established. The effect of the PP carrier resin on the flame retardancy and water resistance of the intumescent‐flame‐retarding PP materials was investigated by using the limited oxygen index (LOI), UL94 test, elemental analysis (EA), thermogravimetric analysis (TGA) and water solubility testing, respectively. In addition, the mechanism of the carrier effect was analysed by melt flow index (MFI), scanning electron microscopy (SEM), and TGA. The experimental results show that with increasing content of carrier resin (PP) in the IFR master batch from 0 to 15 wt%, the flame retardancy LOI of the PP/IFR (25 wt% loading) blend increased from 29.5 to 32, and the UL94 level at 1.6 mm thickness was improved from failure to a V‐0 rating. In addition, the water resistance of a flame‐retarded composite at 25 wt% IFR loading was greatly improved, i.e. after treatment with hot water at 70 °C for 168 h, the reducing rate of element N in the IFR/PP blend decreased from 18.3% with 5 wt% carrier resin to 12.9% with 15 wt% carrier resin, and the LOI reduction rate decreased from 15.3% without any carrier resin to 10.9% with 15 wt% carrier resin, while the flame‐retarded PP with an IFR master batch containing 10–15 wt% carrier resin maintained its UL94 V‐0 rating at 3.2 mm thickness. The improvement in flame retardancy was attributed to the improved flame‐retardant (FR) dispersion due to the carrier resin, while the improved water resistance was explained by the lowered water solubility of the IFR, the improved FR dispersion and the improved compatibility of the FR with the matrix resin due to the carrier resin. Reactive extrusion is a novel way to obtain pelletissed IFRs without powder pollution and their corresponding flame‐retarding materials with a number of desired properties. Copyright © 2004 Society of Chemical Industry
Ethylene–(vinyl acetate) copolymer/carbon fiber conductive composite: effect of polymer–filler interaction on its electrical properties
Authors: Di Wei‐hua , Zhang Guo , Zhao Zhu‐Di , Peng Yi
Published: March 2004

Ethylene–(vinyl acetate) (EVA)/carbon fibre (CF) composites were prepared by changing the content of CF in the composite. To investigate the effect of the interaction between EVA and CF on the electrical properties of the composite, the CF was treated in nitric acid. The interaction between EVA and CF was examined by a solvent‐extraction method. It was found that the interaction of EVA with CF was enhanced due to the chemical absorption of EVA on CF. The correlation of CF content, electrical properties and the formation of polymer–filler gel for the composite with oxidized CF was studied. Although the composites filled with treated CF exhibit a slightly higher resistivity than those filled with untreated CF at room temperature, they show the improved electrical properties, including elimination of the negative‐temperature‐coefficient (NTC) effect, high electrical reproducibility after thermal cycles, and independence of the conductivity on time, which improves the practical applications of positive‐temperature‐coefficient (PTC) materials. Copyright © 2004 Society of Chemical Industry
Modelling of the interactions between a photochromic naphthopyran and a poly(methyl methacrylate) matrix through the variation of the glass transition temperature and application of the energy/volume/mass (EVM) model
Authors: Rauzy Evelyne , Berro Charles , Morel Sébastien , Herbette Gaétan , Lazzeri Véronique , Guglielmetti Robert
Published: March 2004

A quantitative structure property relationship (QSPR) model, called the EVM (energy, volume, mass) model, to calculate the glass transition temperature (Tg) of a poly(methyl methacrylate) matrix as a support of a naphthopyran photochromic pigment, as a function of the concentration of this pigment, is described. The interactions between the photochromic pigment and the polymer matrix, and especially the van der Waals non‐bonding interactions, are important for the photochromic behaviour of the optical material and the commercial availability of glasses. The prediction of Tg through a multiparametric relationship is interesting for the choice of the best conditions of formulation of the couple photochromic pigment–polymer matrix Copyright © 2004 Society of Chemical Industry
Morphology and thermal properties of two polymethacrylates modified by a polymer liquid crystal
Authors: Brostow Witold , Gargallo Ligia , Hormazabal Andrea , Jaklewicz Magdalena , Menard Kevin P , Opazo Alejandra , Radic Deodato
Published: March 2004

We have studied blends of a polymer liquid crystal (PLC) with poly(cyclohexylethyl methacrylate) (PCHEMA) or poly(cyclohexylpropyl methacrylate) (PCHPMA). The PLC is PET/0.6PHB where PET = poly(ethylene terephthalate), PHB = p‐hydroxybenzoic acid and 0.6 is the mole fraction of the latter in the copolymer. The microstructure was studied by scanning electron microscopy (SEM). PCHEMA + PLC (20 wt% of the latter, blend E) has a fine texture with LC islands evenly distributed in the matrix and good adhesion between the phases resulting from their partial miscibility. The PCHPMA + PLC (20 wt% of the latter, blend P) shows only limited compatibility. The SEM results are confirmed by values of the glass transition temperatures Tg determined via thermal mechanical analysis. The Tg value of the blend E is shifted towards the Tg of PLC; Tg of blend P is practically equal to that of PCHPMA. The linear isobaric expansivity αL values for both blends are lower than the respective values for pure PCHPMA and PCHEMA. Thermal stabilities of the blends determined by thermogravimetry are also better than those of pure polymethacrylates. The temperature of 50% weight degradation for blend E is higher than that for pure PCHEMA by more than 60 K Copyright © 2004 Society of Chemical Industry
Soluble aromatic poly(ether amide)s containing aryl‐, alkyl‐, and chloro‐substituted phthalazinone segments
Authors: Zhu Xiuling , Jian Xigao
Published: March 2004

A series of novel aromatic diamines (2–4) containing the alkyl‐, aryl, or chloro‐substituted group of phthalazinone segments were synthesized via two synthetic steps starting from 4‐(3‐R‐4‐hydroxyphenyl)‐2,3‐phthalazinone‐1 (R = Ph, CH3, Cl). Three series of aromatic polyamides containing phthalazinone moieties were prepared through diamines 2–4 reacting with different aromatic dicarboxylic acids via a direct Yamazaki–Higashi phosphorylation polycondensation reaction. The resulting aromatic polyamides had inherent viscosities in the range of 0.40–0.76 dL/g. The thermal property of the polyamides was examined with DSC and thermogravimetric analysis. The glass‐transition temperatures of these polyamides ranged from 298 to 340 °C. The 10% mass‐loss temperature was above 405 °C under nitrogen. Structures of monomers 2–4 and the polymers were confirmed by Fourier transform infrared spectroscopy, 1H NMR, and mass spectrometry. Good solubility of these polymers in polar solvents such as N‐methylpyrrolidone, dimethylformamide, dimethylacetamide (DMAc), and m‐cresol was observed, and tough, flexible films were obtained from the polymer's DMAc solutions. The effect of the substituted group on the physical property of polymers was also investigated. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2026–2030, 2004
Synthesis and characterization of polyaniline doped with organic acids
Authors: Kulkarni Milind V. , Viswanath Annamraju Kasi , Marimuthu R. , Seth Tanay
Published: March 2004

Spectroscopic [UV–visible and Fourier transform IR (FTIR)] and thermal properties of chemically synthesized polyanilines are found to be affected by varying the protonation media (acetic, citric, oxalic, and tartaric acid). The optical spectra show the presence of a greater fraction of fully oxidized insulating pernigraniline phase in polyaniline doped with acetic acid. In contrast, the selectivity in the formation of the conducting phase is higher in oxalic acid as a protonic acid media. The FTIR spectra of these polymers reveal a higher ratio of the relative intensities of the quinoid to benzenoid ring modes in acetic acid doped polyaniline. Scanning electron micrographs revealed a sponge‐like structure derived from the aggregation of the small granules in acetic acid and oxalic acid doped polyaniline. A three‐step decomposition pattern is observed in all the polymers, regardless of the protonic acid used for the doping. The second step loss related to the loss of dopant is found to be higher in the oxalic acid doped polymer. In accordance with these results the conductivity is also found to be higher in oxalic acid doped material. The temperature dependent conductivity measurements show the thermal activated behavior in all the polymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2043–2049, 2004
Polymerization of isoprene with η5‐C5H4(tert‐Bu)TiCl3/MAO catalyst
Authors: Miyazawa Akira , Kase Toshio , Shibuya Tomohiro
Published: March 2004

cis‐Selective polymerizations of isoprene with the catalysts composed of η5‐C5H4(R)TiCl3 (1; RH, 2; tert‐Bu) and methylaluminoxane were investigated. Both catalysts showed remarkable catalytic activities for the polymerization of isoprene. The polymerization activities were strongly affected by the substituent introduced on cyclopentadienyl ring. Introduction of bulky tert‐butyl group was found to be effective for enhancement of polymerization activity, but the cis‐content of polyisoprene prepared by the 2/MAO catalyst was lower than that by 1/MAO catalyst. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1841–1844, 2004
Green‐emitting poly[(1,3‐phenylenevinylene)‐alt‐ (1,4‐phenylenevinylene)]s: Effect of the substitution patterns on the optical properties
Authors: Liao Liang , Pang Yi , Ding Liming , Karasz Frank E.
Published: March 2004

Green‐emitting substituted poly[(2‐hexyloxy‐5‐methyl‐1,3‐phenylenevinylene)‐alt‐(2,5‐dihexyloxy‐1,4‐phenylenevinylene)]s (6) were synthesized via the Wittig–Horner reaction. The polymers were yellow resins with molecular weights of 10,600. The ultraviolet–visible (UV–vis) absorption of 6 (λmax = 332 or 415 nm) was about 30 nm redshifted from that of poly[(2‐hexyloxy‐5‐methyl‐1,3‐phenylenevinylene)‐alt‐(1,4‐phenylenevinylene)] (2) but was only 5 nm redshifted with respect to that of poly[(1,3‐phenylenevinylene)‐alt‐(2,5‐dihexyloxy‐1,4‐phenylenevinylene)] (1). A comparison of the optical properties of 1, 2, and 6 showed that substitution on m‐ or p‐phenylene could slightly affect their energy gap and luminescence efficiency, thereby fine‐tuning the optical properties of the poly[(m‐phenylene vinylene)‐alt‐(p‐phenylene vinylene)] materials. The vibronic structures were assigned with the aid of low‐temperature UV–vis and fluorescence spectroscopy. Light‐emitting‐diode devices with 6 produced a green electroluminescence output (emission λmax ∼ 533 nm) with an external quantum efficiency of 0.32%. Substitution at m‐phenylene appeared to be effective in perturbing the charge‐injection process in LED devices. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1820–1829, 2004
Stereoselective nucleophilic substitution of poly(vinyl chloride) with potassium 4‐acetamidothiophenolate
Authors: Martínez Gerardo , Millán José Luis
Published: March 2004

The nucleophilic substitution reaction of poly(vinyl chloride) (PVC) with potassium 4‐acetamidothiophenolate was performed in a cyclohexanone solution. The quantitative microstructural analysis, as a function of the conversion, was followed by 13C NMR spectroscopy. Through a comparison of the microstructural changes with the degree of substitution, a small fraction of mmr tetrads was found to react occasionally with the central chlorine of the mr triad instead of the mm, such as for sodium benzenethiolate (NaBT). This conclusion was confirmed by Fourier transform infrared results. However, unlike NaBT, the evolution of the glass‐transition temperature (Tg) with the degree of conversion changed with the degree of substitution similarly to the ratio of the extents to which mmr and rrmr structures intervened in the substitution reaction. From these studies, it followed that the specific interactions due to the polar nature of the nucleophile enhanced the molecular‐microstructure‐based mechanisms, which were responsible for Tg. Such a novel quantitative correlation, compared with more tentative ones obtained previously, presents valuable insight into the role of the stereochemical microstructure in the glass‐transition process in PVC. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1857–1867, 2004
Synthesis and characterization of novel aryl‐ethynylene polymers of tuned rigidity/flexibility
Authors: Winter Dominik , Eisenbach Claus D.
Published: March 2004

New poly(aryl‐ethynylene) polymers of tuned rigidity/flexibility were synthesized by a palladium‐catalyzed polycondensation. The Sonogashira–Hagihara‐type coupling reaction of 2,5‐diethynyl‐4‐dodecyltoluene with 2,5‐ and/or 3,5‐dibromopyridine led to polymers of different rigidity/flexibility simply by varying the ratio of 2,5‐ to 3,5‐dibromopyridine charged in the polycondensation reaction. The ratio of para–meta linkages at the pyridine moiety in the polymer backbone was determined by NMR spectroscopy. The combination of molecular weight data obtained from vapor pressure osmometry and the use of oligomeric model compounds allowed us to establish a polymer‐specific gel permeation chromatography calibration. Information about the molecular conformation of the polymers in solution were obtained by small‐angle X‐ray scattering (SAXS) experiments. The glass‐transition and melting temperatures varied systematically with the degree of rigidity/flexibility and could be directly related to the conformational changes as reflected from the SAXS data. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1919–1933, 2004
Parallel kinetic investigation of 2‐oxazoline polymerizations with different initiators as basis for designed copolymer synthesis
Authors: Hoogenboom Richard , Fijten Martin W. M. , Schubert Ulrich S.
Published: March 2004

The systematical kinetic investigations of four 2‐substituted‐2‐oxazoline monomers with four initiators at two temperatures and four monomer/initiator ratios are described. To cover this broad range of variables (128 different combinations), an automated synthesizer was used to accelerate the investigations and to provide highly comparable results. With both gas chromatography and gel permeation chromatography, the livingness and the polymerization rates were determined for the different polymerizations. The resulting insights in the kinetics were used for the directed synthesis of truly random copolymers and copolymers with composition drift. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1830–1840, 2004
Initiation process of L‐lactide polymerization carried out with zirconium(IV) acetylacetonate
Authors: Dobrzynski Piotr
Published: March 2004

Lactide polymerization using zirconium(IV) acetylacetonate [Zr(acac)4] as an initiator was investigated. In the reaction between Zr(acac)4 and the monomer molecule, lactide deprotonation and the release of acetylacetone occurred. The structures of the obtained complexes were analyzed with high‐resolution NMR spectroscopy. A computational method was used to calculate the hypothetical structures. The role of the obtained complexes in the initiation of polymerization and the reaction of chain growth was proposed. The influence of the reaction temperature on the structures of the complexes was investigated. Polylactide chain growth proceeded by an insertion‐coordination mechanism. The polymer chain grew on one ligand, which was formed in advance from a deprotonated lactide. The molecular masses of the obtained polymers were the same as the theoretical masses and were directly proportional to the reaction conversion. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1886–1900, 2004
High‐throughput experimentation in atom transfer radical polymerization: A general approach toward a directed design and understanding of optimal catalytic systems
Authors: Zhang Huiqi , Marin Veronica , Fijten Martin W. M. , Schubert Ulrich S.
Published: March 2004

High‐throughput experimentation (HTE) was successfully applied in atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) for the rapid screening and optimization of different reaction conditions. A library of 108 different reactions was designed for this purpose, which used four different initiators [ethyl 2‐bromoisobutyrate, methyl 2‐bromopropionate, (1‐bromoethyl)benzene, and p‐toluenesulfonyl chloride], five metal salts (CuBr, CuCl, CuSCN, FeBr2, and FeCl2), and nine ligands (2,2′‐bipyridine and its derivatives). The optimal reaction conditions for Cu(I) halide, CuSCN, and Fe(II) halide‐mediated ATRP systems with 2,2′‐bipyridine and its 4,4′‐dialkyl‐substituted derivatives as ligands were determined. Cu(I)‐mediated systems were better controlled than Fe(II)‐mediated ones under the examined conditions. A bipyridine‐type ligand with a critical length of the substituted alkyl group (i.e., 4,4′‐dihexyl 2,2′‐bipyridine) exhibited the best performance in Cu(I)‐mediated systems, and p‐toluenesulfonyl chloride and ethyl 2‐bromoisobutyrate could effectively initiate Cu(I)‐mediated ATRP of MMA, resulting in polymers with low polydispersities in most cases. Besides, Cu(I) halide‐mediated ATRP with 4,5′‐dimethyl 2,2′‐bipyridine as the ligand and p‐toluenesulfonyl chloride as the initiator proved to be better controlled than those with 4,4′‐dimethyl 2,2′‐bipyridine as the ligand, and polymers with much lower polydispersities were obtained in the former cases. This successful HTE example opens up a way to significantly accelerate the development of new catalytic systems for ATRP and to improve the understanding of structure–property relationships of the reaction systems. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1876–1885, 2004
Tetrakis Sn(IV) alkoxides as novel initiators for living ring‐opening polymerization of lactides
Authors: Kalmi Mikko , Lahcini Mohammed , Castro Pascal , Lehtonen Olli , Belfkira Ahmed , Leskelä Markku , Repo Timo
Published: March 2004

The use of tetrakis Sn(IV) alkoxides as highly active initiators for the ring‐opening polymerization of D,L‐lactide is reported. The activities of prepared Sn(IV) tetra‐2‐methyl‐2‐butoxide, Sn(IV) tetra‐iso‐propoxide, and Sn(IV) tetra‐ethoxide were compared to a well‐known ring‐opening polymerization initiator system, Sn(II) octoate activated with n‐butanol. All polymerizations were conducted at 75 °C in toluene. The activities of tetrakis Sn(IV) alkoxides grew in order of increasing steric hindrance, and the bulky Sn(IV) alkoxides showed higher activity than the Sn(II) octoate/butanol system. The living character of the polymerization was demonstrated in homopolymerization of D,L‐lactide and in block copolymerization of L‐lactide with ϵ‐caprolactone. 1H, 13C, and 119Sn NMR were used to characterize the prepared Sn(IV) alkoxides and the polymer microstructure, and size exclusion chromatography was used to determine the molar masses as well as the molar‐mass distributions of the polymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1901–1911, 2004
Synthesis and characterization of new polybenzimidazopyrrolones derived from pyridine‐bridged aromatic tetraamines and dianhydrides
Authors: Liu Jin‐Gang , Wang Li‐Fang , Yang Hai‐Xia , Li Hong‐Shen , Li Yan‐Feng , Fan Lin , Yang Shi‐Yong
Published: March 2004

A series of new polybenzimidazopyrrolones (polypyrrolone, PPy) were synthesized by polycondensation of pyridine‐bridged aromatic tetraamines, including 2,6‐bis (3′,4′‐diaminophenyl)‐4‐phenylpyridine and 2,6‐bis(3′,4′‐ diaminophenyl)‐4‐(3″‐trifluoromethyl)phenyl pyridine, with various aromatic dianhydrides. Experimental results indicated that the PPys, multiaromatic conjugated and semiladder polymers, showed good thermal stabilities with thermal‐decomposition temperatures of about 500 °C and residual weight retention at 750 °C as high as 84%. PPy films could be obtained by casting the precursor solution, poly(amide amino acid) on glass substrate, followed by thermal dehydrating at elevated temperatures. The polymer films exhibited excellent alkaline hydrolysis resistance, which retained their original shapes and toughness after boiling 7 days in 10% sodium hydroxide solution. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1845–1856, 2004
N,N,N′,N′,N″‐penta(methyl acrylate)diethylenetriamine: A novel ligand for atom transfer radical polymerization of methyl methacrylate
Authors: Chu Juan , Chen Jin , Zhang Keda
Published: March 2004

A novel ligand, N,N,N′,N′,N″‐penta (methyl acrylate) diethylenetriamine (MA5‐DETA), was synthesized by the reaction of diethylenetriamine with methyl acrylate in almost quantitive yield. The polymerizations of methyl methacrylate with MA5‐DETA as the ligand and α,α‐dichlorotoluene (DCT) and ethyl 2‐bromoisobutyrate (2‐EBiB) as the initiators, respectively, under different conditions were examined. The polymerization with CuCl/MA5‐DETA/DCT was closely controlled in bulk and gave polymers with quite narrow molecular weight distributions (Mw/Mn's) of 1.16–1.29. The polymerization with the system CuBr/MA5‐DETA/EBiB in bulk gave high activity. However, the system was not well controlled and gave the polymers with Mw/Mn = 1.35–1.53. The solution polymerization in anisole with CuBr/MA5‐DETA/EBiB showed a better‐controlled nature. Moreover, the addition of CuBr2 into the aforementioned system can further improve its controllability. The Mw/Mn's of the resulting polymers ranged from 1.11 to 1.21. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1963–1969, 2004
Photoinitiated grafting of maleic anhydride onto polypropylene
Authors: Pan Bo , Viswanathan Kalyanaraman , Hoyle Charles E. , Moore Robert B.
Published: March 2004

The photoinitiated grafting of maleic anhydride (MAH) onto polypropylene with the use of benzophenone (BP) as the initiator has been investigated. In comparison with the process of thermally initiated grafting with peroxide as the initiator, photoinitiated grafting affords a higher grafting efficiency. The efficient photografting sensitized by BP can be explained by two possible mechanistic processes: the sensitization of the formation of the excited triplet state of MAH by BP and electron transfer followed by proton transfer between MAH and the benzopinacol radical, which may operate together. In the former case, the generated MAH excited triplet state abstracts a hydrogen from the polymer substrate to initiate grafting. A rate constant of 3.6 × 109 M −1 s −1 has been determined by laser flash photolysis for the process of quenching the excited triplet state of BP with ground‐state MAH. In comparison, the rate constant for the quenching of the excited triplet state of BP by hydrogen abstraction has been determined to be 4.1 × 105 M −1 s −1. In a study of photografting using a model compound, 2,4‐dimethylpentane, as a small‐molecule analogue of polypropylene, the loss of BP was significantly reduced upon the addition of MAH, and this is consistent with the proposed mechanistic processes. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1953–1962, 2004
Near‐infrared spectroscopy investigation of water effects on the cationic photopolymerization of vinyl ether systems
Authors: Lin Yan , Stansbury Jeffrey W.
Published: March 2004

Real‐time Fourier transform near‐infrared spectroscopy has been used to monitor monomer and water concentrations simultaneously during cationic vinyl ether photopolymerization. The use of near‐infrared peak area methods allows the water content to be conveniently and nondestructively determined in any monomer or polymer for which the water peak has previously been calibrated by gravimetric analysis. Although the shape of the absorption band due to absorbed water in a monomer changes with the quantity of water, the integrated intensity from about 5350 to 4900 cm−1 can be correlated directly to the water concentration, and this region is well removed from the vinyl‐based absorption at approximately 6190 cm−1. This approach provides a highly informative, dynamic technique for examining the influence of moisture on polymerization reactions. Significant differences have been observed in the effects of absorbed water on the cationic photopolymerization kinetics of vinyl ether monomers with or without an OH group. Along with the rapid consumption of water coupled to vinyl ether polymerization, acid‐catalyzed hydrolysis reactions have also been spectroscopically observed, giving rise to the formation of aldehyde groups. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1985–1998, 2004
Synthesis of hydrophilic sorbents from N‐vinylimidazole/divinylbenzene and the evaluation of their sorption properties in the solid‐phase extraction of polar compounds
Authors: Fontanals Núria , Maria Marcé Rosa , Galià Marina , Borrull Francesc
Published: March 2004

This article reports the synthesis of N‐vinylimidazole/divinylbenzene resins by suspension polymerization. Several polymerization conditions were tested to achieve a quantitative incorporation of the N‐vinylimidazole monomer into the final polymer while a high specific surface area was maintained. The retention properties of several copolymers with different nitrogen contents were evaluated with the solid‐phase extraction of polar compounds from water samples, and the best results were obtained for a polymer containing 6.3% N with a surface area of 627 m2 g−1. The sorption properties of the resins were compared to those of styrene–divinylbenzene and other copolymers containing nitrogen, and the results were best for the new sorbents with N‐vinylimidazole as the polar monomer. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2019–2025, 2004
Synthesis of phosphorus‐containing vinyl ether monomers and oligomers and their photoinitiated polymerization
Authors: Minegishi Shouji , Otsuka Tetsurou , Kameyama Atsushi , Nishikubo Tadatomi
Published: March 2004

Divinyl ether monomers containing phosphorous residues were synthesized by the addition reaction of glycidyl vinyl ether (GVE) with various phosphonic dichlorides or dichlorophosphates with quaternary onium salts as catalysts. The reaction of GVE with phenylphosphonic dichloride gave bis[1‐(chloromethyl)‐2‐(vinyloxy)ethyl]phenylphosphonate (1a) in a 77% yield. The polycondensation of 1a with terephthalic acid was also carried out with 1,8‐diazabicyclo[5.4.0]undecene‐7 (DBU) as a condensing agent to afford the corresponding phosphorus‐containing polyester. A multifunctional monomer containing both vinyl ether groups and methacrylate groups was prepared by the reaction of 1a with methacrylic acid with DBU. The photoinitiated cationic polymerization of these vinyl ether compounds proceeded rapidly with bis[4‐(diphenylsulfonio)phenyl]sulfide‐bishexafluorophosphate as the cationic photoinitiator without a solvent upon ultraviolet irradiation. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2031–2042, 2004
A new approach to estimating shelf‐life
Authors: Kiermeier Andreas , Jarrett Richard G. , Verbyla Arūnas P.
Published: March 2004

The current approach to the estimation of shelf‐life and the determination of the label shelf‐life as detailed in the International Conference on Harmonisation guidelines to industry is presented. The shortcomings of the status quo are explained and a possible solution is offered, which gives rise to a new definition of shelf‐life. Several methods for calculating a label shelf‐life are presented and investigated using a simulation study. Recommendations to adopt the new definition and to increase sample sizes are made. Copyright © 2004 John Wiley & Sons, Ltd.
A note on sample size savings with the use of a single well‐controlled clinical trial to support the efficacy of a new drug
Authors: Darken Patrick F. , Ho Shu‐Yen
Published: March 2004

In terms of the risk of making a Type I error in evaluating a null hypothesis of equality, requiring two independent confirmatory trials with two‐sided p‐values less than 0.05 is equivalent to requiring one confirmatory trial with two‐sided p‐value less than 0.001 25. Furthermore, the use of a single confirmatory trial is gaining acceptability, with discussion in both ICH E9 and a CPMP Points to Consider document. Given the growing acceptance of this approach, this note provides a formula for the sample size savings that are obtained with the single clinical trial approach depending on the levels of Type I and Type II errors chosen. For two replicate trials each powered at 90%, which corresponds to a single larger trial powered at 81%, an approximate 19% reduction in total sample size is achieved with the single trial approach. Alternatively, a single trial with the same sample size as the total sample size from two smaller trials will have much greater power. For example, in the case where two trials are each powered at 90% for two‐sided α=0.05 yielding an overall power of 81%, a single trial using two‐sided α=0.001 25 would have 91% power. Copyright © 2004 John Wiley & Sons, Ltd.
An application of a multi‐stage strategy involving confidence intervals to evaluate whether a response rate is favourable or not
Authors: Murray Sharon C. , Otterness Mary F. , Forster John K. , Catellier Diane J. , Koch Gary G.
Published: March 2004

In early clinical development of new medicines, a single‐arm study with a limited number of patients is often used to provide a preliminary assessment of a response rate. A multi‐stage design may be indicated, especially when the first stage should only include very few patients so as to enable rapid identification of an ineffective drug. We used decision rules based on several types of nominal confidence intervals to evaluate a three‐stage design for a study that includes at most 30 patients. For each decision rule, we used exact binomial calculations to determine the probability of continuing to further stages as well as to evaluate Type I and Type II error rates. Examples are provided to illustrate the methods for evaluating alternative decision rules and to provide guidance on how to extend the methods to situations with modifications to the number of stages or number of patients per stage in the study design. Copyright © 2004 John Wiley & Sons, Ltd.
The double triangular test in practice
Authors: Whitehead John , Todd Susan
Published: March 2004

The double triangular test was introduced twenty years ago, and the purpose of this paper is to review applications that have been made since then. In fact, take‐up of the method was rather slow until the late 1990s, but in recent years several clinical trial reports have been published describing its use in a wide range of therapeutic areas. The core of this paper is a detailed account of five trials that have been published since 2000 in which the method was applied to studies of pancreatic cancer, breast cancer, myocardial infarction, epilepsy and bedsores. Before those accounts are given, the method is described and the history behind its evolution is presented. The future potential of the method for sequential case–control and equivalence trials is also discussed. Copyright © 2004 John Wiley & Sons, Ltd.
Applications of graphic method to C20, C60, and achiral single‐wall nanotubes
Authors: Zhang Liling , Wu Wei , Mo Yirong , Zhang Qianer
Published: March 2004

A reduced Hückel graph (HG) algorithm within the Hückel theory is presented and applied to C20, C60, and achiral single‐wall nanotubes (SWNTs). The applications show that reduced HG algorithm is a more efficient way to the secular problem in the Hückel theory than other algorithms based on the Hückel method, although they give the same results. Furthermore, the applications of HG to achiral SWNT provide a general electronic structure not only on infinite achiral tubes, but also on finite‐sized tubes. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
New realizations of electronic configuration interaction spaces
Authors: Panin A. I.
Published: March 2004

The general properties of new models of the electronic spaces based on the notion of (p, q)‐sheaves are studied. The interrelation between simple sheaves and density operators is established. Explicit expressions for the transformed reduced Hamiltonians in terms of the standard creation‐annihilation operators are presented. The general scheme of parametrization of p‐electron states by κ‐electron means (κ = 2, 3, …) is described and studied in detail for the case of sheaves induced by κ‐electron wave functions. It is demonstrated that, under certain conditions, a p‐electron problem may be reformulated as the eigenvalue problem in κ‐electron space equipped with certain p‐electron metric. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Ab initio study of hydrogen bonding interaction and photoinduced electron transfer between 4‐nitroquinoline‐1‐oxide and tryptophan
Authors: Liu Ji‐Feng , Li Xiang‐Yuan , Zhu Quan
Published: March 2004

In the present article, the electronic structure of 4‐nitroquinoline‐1‐oxide (4NQO) has been theoretically investigated at the level of HFSCF/6‐31G**. Conformation of monomeric 4NQO has been found to be the most stable when the nitro group twists from the quinoline plane by about 24°. The absorption spectra of the twisted 4NQO have been calculated by using complete active space self‐consistent field method. The hydrogen bonded complexes of 4NQO and tryptophan have been intensively studied. The absorption spectra of the most stable complex have been calculated to investigate the photoinduced electron transfer between 4NQO and tryptophan. The first and second excited singlet states are found to be charge‐separated. Population analysis shows that the low‐lying triplet states are charge‐separated as well, except for the lowest one that presents the characters of a locally excited state. A solvent effect on transition energies has been considered based on the Ooshika–Lippert–Martaga equation. Theoretical study shows that the optical excitation can lead to charge separation in the 4NQO–tryptophan complex. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Bound state calculations for some three‐body electronic and muonic atomic systems with Fues‐Kratzer–type potential
Authors: Yalçin Zeynel
Published: March 2004

The coupled Schrödinger equation for three‐body atomic systems such as Ps−(e+e−e−), Mu(μ+e−e−), p+μ−μ−, d+μ−μ−, and t+μ−μ− is solved by using the hyperspherical harmonic‐generalized Laguerre polynomial expansion method (HHGLP). Ground‐state eigenenergies are calculated for the certain number of basis functions. The eigenenergies of the first excited states are obtained for both pure Coulomb, V(r, Ω) = $\hat{Z}$(Ω)/r, and Fues‐Kratzer‐type (FK‐type) potential, V(r, Ω) = $\hat{Z}$(Ω)/r + $\hat{A}$(Ω)/r2. As an example, to illustrate the effect of FK‐type interaction on the lowest excited states, the eigenenergies of the Mu− ion are given together as a function of the certain number of basis functions for both potentials. Our results were compared with the other theoretical calculations. Ground‐state eigenenergies of atoms such as X+Y−Y− as a function of the reduced mass were investigated. The potential curves of the ground and first excited states of Ps−(e+e−e−), Mu−(μ+e−e−), p+μ−μ− systems were obtained by a diagonalization process. It is pointed out that the FK‐type potential makes the HH method more useful and more extended for atomic calculations. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Discussion on the variable Wolfsberg–Helmholtz parameter, a new simplified Löwdin transformation and the characteristic structure of the transformed EHT Hamiltonian matrices
Authors: Carbó‐Dorca Ramon
Published: March 2004

Three related problems are discussed: (1) the variable nature of the Wolfsberg–Helmholtz parameter and its relationship with the overlap eigenvalue range; (2) the possibility of deriving an efficient framework, describing a simplified Löwdin transformation to solve generalized secular equations; and (3) the structure of the transformed classical EHT Hamiltonian. This work shows how the simplified Löwdin transformation permits expression of the resulting transformed Hamiltonian elements by means of inward matrix products and total matrix sums. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Spontaneous assembly of ordered nanoclusters and nanowires
Authors: Liang Xue‐Jin , Li Jian‐Long , Liu Xi , Wang Jun‐Zhong , Liu Hong , Xue Qi‐Kun , Jia Jin‐Feng
Published: March 2004

A novel strategy for the spontaneous formation of spatially ordered nanoclusters and nanowires by taking advantage of templates is reported. With this method, a large‐scale perfectly ordered identical‐size indium nanocluster array and ordered indium nanowire array are obtained on Si(111)‐(7 × 7) and Si(001)‐2 × n, respectively. It can be applied also to other metals such as Ga, Al, Ag and Mn. The atomic structures of the indium nanoclusters and nanowires are determined by in situ scanning tunnelling microscopy analysis, combined with first‐principles theoretical calculations. The formation mechanism is discussed based on the results. Copyright © 2004 John Wiley & Sons, Ltd.
Morphological evolution of erbium disilicide nanowires on Si(001)
Authors: Yang Jianshu , Cai Qun , Wang X.‐D. , Koch R.
Published: March 2004

The morphological evolution of ErSi2 nanowires on Si(001) with Er coverage was investigated by scanning tunnelling microscopy, low‐energy electron diffraction and x‐ray diffraction. At low Er coverages, elongated ErSi2 nanowires in a hexagonal crystal structure are formed. The nanowires are exclusively oriented perpendicular to the dimer rows of the Si(001) substrate, thus suggesting a method to control the nanowire arrangement via the substrate configuration. At 3 ML of Er rectangular islands with flat tops are observed, which crystallize in the tetragonal lattice of ErSi2. Our experiments suggest that the structural transformation from hexagonal to tetragonal takes place when the nanostructures reach the height of the c‐axis of the tetragonal unit cell. Copyright © 2004 John Wiley & Sons, Ltd.