bluuebunny/crossref_metadata_2025_split huggingface dataset:
A pharmacoeconomic comparison of misoprostol/diclofenac with diclofenac
Authors: Morant S. V. , Shield Michael J. , Davey P. G. , MacDonald T. M. 
Published: October 2002

AbstractObjectivesTo estimate the economic impact of misoprostol/diclofenac in a fixed combination tablet compared with diclofenac.DesignCohort study with a prospectively constructed, population‐based, record‐linkage database containing details of exposure to all community dispensed NSAIDs and all admissions to hospital for upper gastrointestinal (GI) diagnoses. Costs associated with each study drug exposure were analysed using generalized linear models.SettingThe population of Tayside, Scotland.SubjectsSubjects aged 20 years and over who received misoprostol/diclofenac or any other NSAID between January 1989 and 31 December 1995.Main outcome measuresTotal costs for the number of days of exposure to diclofenac and misoprostol/diclofenac, plus costs of concomitant ulcer healing drug therapy plus endoscopy procedures plus costs of admissions to hospital for upper GI diagnoses.ResultsThe rate of hospitalization with gastrointestinal events was 30% higher among patients receiving diclofenac than that for patients receiving misoprostol/diclofenac. Among patients who received diclofenac and an ulcer‐healing drug (UHD), the event rate was more than twice that for patients receiving misoprostol/diclofenac. In patients with a prior GI history, switching from diclofenac to misoprostol/diclofenac would reduce the costs of hospitalization. The resulting savings would more than offset the extra prescription costs. In patients without a prior GI history, the greatest potential saving would arise due to reduced use of UHDs and net savings would occur in subjects aged between 60 and 70 years of age or more.ConclusionUse of misoprostol/diclofenac instead of diclofenac can produce cost savings due to reduced hospitalization rates and decreased use of UHDs in subjects with a prior history of GI disease and in older subjects without prior GI disease. These findings have implications for the management of patients who require treatment with NSAIDs. Copyright © 2002 John Wiley & Sons, Ltd.
Magnetic polymer microsphere with photoconductivity: preparation and characterization of iron(III) phthalocyanine covalently bonded on to polystyrene microsphere surface
Authors: Zhang Junhua , Ding Xiaobin , Peng Yuxing , Mang Wang 
Published: October 2002

AbstractA novel magnetic polymer microsphere displaying photoconductivity was prepared by covalently bonding iron(III) phthalocyanine (FePc) onto a polystyrene microsphere with hydroxyl groups (PSA). PSA was synthesized by dispersion polymerization in the presence of Fe3O4 magnetic fluid. The structure and properties of the magnetic polymer microsphere were identified by infrared spectoscopy. elemental analysis and scanning electron microscopy. The results showed that this kind of microsphere combines the merits of magnetic responsiveness and photoconductivity. The application of magnetic polymer microspheres for absorption of bovine serum albumin (BSA) was characterized at different temperatures, different incubation times, different pH values and different initial BSA concentrations.© 2002 Society of Chemical Industry
Procrastination, conscientiousness, anxiety, and goals: Exploring the measurement and correlates of procrastination among school‐aged children
Authors: Scher Steven J. , Osterman Nicole M. 
Published: October 2002

AbstractWe explore the reliability and validity of a self‐report measure of procrastination and conscientiousness designed for use with third‐ to fifth‐grade students. The responses of 120 students are compared with teacher and parent ratings of the student. Confirmatory and exploratory factor analyses were also used to examine the structure of the scale. Procrastination and conscientiousness are highly correlated (inversely); evidence suggests that procrastination and conscientiousness are aspects of the same construct. Procrastination and conscientiousness are correlated with the Physiological Anxiety subscale of the Revised Children's Manifest Anxiety Scale, and with the Task (Mastery) and Avoidance (Task Aversiveness) subscales of Skaalvik's (1997) Goal Orientation Scales. Both theoretical implications and implications for interventions are discussed. © 2002 Wiley Periodicals, Inc.
Extended charge delocalization to 4‐phenoxy substituent in benzhydryl solvolysis: possible contribution of non‐canonical resonance structure in the cationic transition state
Authors: Liu Kwang‐Ting , Chuang Chih‐Shiow , Jin Bih‐yaw 
Published: October 2002

AbstractSolvolytic reactivities of 4‐nitrobenzhydryl bromides (2b–5b) and chlorides (2c–5c) were studied using single‐ and dual‐parameter Grunwald–Winstein‐type correlation analyses with YBnX and Y
xBnX scales, respectively. Extended charge delocalization over two aryl rings at cationic transition states were found for 3 and 5, but not for 2 or 4. Calculations of the charge distributions in 3c and in the corresponding cation 3a were performed using a Hartree–Fock approximation (RHF/6‐31G* basis set) and density functional models (pBP/DN** and other basis sets), respectively, on Mulliken population analysis and on electrostatic potential analysis. The possible contribution of non‐canonical resonance structure is discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Contrasting effect of guanidinium salts on kinetics of the Diels–Alder reaction
Authors: Kumar Anil , Phalgune Usha D. , Pawar Sanjay S. 
Published: October 2002

AbstractAqueous solutions of guanidinium perchlorate (GnClO4), bromide (GnBr), chloride (GnCl) and acetate (CH3COOGn) inhibit the reaction rates and endo products for the cyclopentadiene–methyl acrylate (CPMA) reaction, whereas that of guanidinium sulfate (Gn2SO4) accelerates them. These contrasting results obtained for the guanidinium salts are interpreted in terms of the salting‐in and ‐out phenomena and by salting coefficients computed from the scaled particle theory. The contrasting effect of Gn2SO4 on the kinetic profiles of the Diels–Alder reactions reported for the first time can be attributed to the dominant role of SO42− over Gn+ ion. It is also shown how the salting‐out effect of NaCl can be neutralized by the salting‐in effect of GnCl in the above reaction. This effect can also be explained in terms of mixing of hydrophilic with hydrophobic cationic species. The effects of the guanidinium salts are also supported by experimental data on solubility, surface tension, volume, compressibility and activation volume. The activation volume of the CPMA reaction calculated from the experimental volumetric data is shown to be salt dependent. Copyright © 2002 John Wiley & Sons, Ltd.
Molecular structure effects on the kinetics of hydroxyl radical addition to azo dyes
Authors: Destaillats Hugo , Turjanski Adrián G. , Estrin Darío A. , Hoffmann Michael R. 
Published: October 2002

AbstractThe effect of the molecular structure of azobenzene and related azo dyes on their reactivity towards .OH radicals in water was investigated by performing ultrasonic irradiation experiments on their aqueous solutions and density functional theory (DFT) calculations. Sonolysis of azobenzene, methyl orange, o‐methyl red and p‐methyl red was performed at a frequency of 500 kHz and 50 W applied power under air saturation. Under such irradiation conditions, these molecules were shown to decompose through .OH radical addition reactions taking place in the bulk liquid. The ortho isomer of methyl red reacted at significantly higher rates (nearly 30% higher) than the other three studied compounds in non‐buffered aqueous solutions. In contrast, measurements performed at lower pH (10 mM HNO3), at which the carboxylic group vicinal to the azo group is protonated, yielded a similar reaction rate for all four substrates, i.e. the specific acceleration observed in the ortho‐substituted dye disappeared with protonation. These results were rationalized by the computation of formation energies of the adduct originated in the .OH addition to the azo group, performing DFT calculations combined with the polarized continuum model (PCM) of solvation. The calculations suggest that intramolecular H‐bonding in the o‐methyl red–OH adduct provides extra stabilization in that particular case, which correlates with the observed higher addition rates of .OH radical to the anionic form of that isomer in non‐buffered solutions. On the other hand, the energy changes calculated for the .OH addition to an o‐methyl red molecule which is protonated in the carboxylic group (representative of the situation at pH 2) do not differ significantly from those computed for the other three molecules studied. Copyright © 2002 John Wiley & Sons, Ltd.
Gas‐phase elimination reactions of 4‐arylideneimino‐2‐cyanoethyl‐1,2,4‐triazol‐3(2H)‐ones, their thione analogues and 2‐glucosyl‐1,2,4‐triazole‐3(2H)‐thiones: a kinetic and mechanistic study
Authors: Al‐Awadi Nouria A. , Ibrahim Yehia A. , Dib Hicham , Kaul Kamini 
Published: October 2002

AbstractSeveral 4‐arylidenimino‐2‐cyanoethyl‐1,2,4‐triazol‐3(2H)‐ones, their 3(2H)‐thiones and 2‐glucosyl‐1,2,4‐triazol‐3(2H)‐thiones (1–12) were synthesized. Selective pyrolytic deprotection of these derivatives was studied in the gas phase and the kinetics of the reactions were measured for each compound. First‐order rate constants measured over a 45 °C temperature range were used to calculate the Arrhenius activation parameters. A comparison of the products and the kinetic behavior of the thermal decomposition of these compounds are discussed. Copyright­© 2002 John Wiley & Sons, Ltd.
Reactivity of some tertiary chlorides with olefinic and methoxy neighboring groups. A case of extended π, n‐participation
Authors: Jurić Sandra , Kronja Olga 
Published: October 2002

AbstractTertiary 2‐chloro‐2‐methyl‐5‐methoxypentane (2) solvolyzes with a significantly reduced secondary β‐deuterium kinetic isotope effect (substrate with two trideuteromethyl groups), and with smaller entropy and enthalpy of activation than the reference saturated analog 4 [kH/kD = 1.35 ± 0.01 VS kH/kD = 1.79 ± 0.01; ΔΔH≠ = −11 kJ mol−1; ΔΔS≠ = −30 J mol−1 K−1, in 80% (v/v) aqueous ethanol], indicating participation of the methoxy group in the rate‐determining step. 2‐Chloro‐2,5‐dimethyl‐8‐methoxy‐5(E)‐octene (3) solvolyzes with a further reduction of the isotope effect, and drastically smaller activation parameters [kH/kD = 1.16 ± 0.01; ΔΔH≠ = −33 kJ mol−1; ΔΔS≠ = −106 J mol−1 K−1, in 80% (v/v) aqueous ethanol], suggesting that the solvolysis of 3 proceeds with extended π, n‐participation, i.e. the assistance of both neighboring groups occurs in the rate‐determining step. Copyright © 2002 John Wiley & Sons, Ltd.
Microsolvated ion stereochemistry
Authors: Speranza Maurizio 
Published: October 2002

AbstractModeling the evolution of ion–dipole pairs in a dynamic environment, such as in a solvent cage, requires the knowledge of the intrinsic structural and electronic factors governing their behavior in the unsolvated or microsolvated state. An experimental methodology has been developed to this purpose which is based on the generation of tailor‐made ionic adducts in gaseous inert media and the investigation of their evolution to products. A survey of the most recent applications of this approach to the gas‐phase study of the mechanism and the stereochemistry of ionic substitution and addition reactions is reported. Copyright © 2002 John Wiley & Sons, Ltd.
Ab Initio studies of aryl σ‐ and Π‐complexes: neutral and charged electrophiles
Authors: Smith William B. 
Published: October 2002

AbstractThe ab initio MP2/6–311 ++ G** method was employed to examine the interaction of five electrophiles, Cl2, Br2 NO+, SiH3+ and CH3+, with benzene. These groups exhibited a full range of complexation from true π‐complexes to full σ‐complexes (Wheland ions). The energy of complex formation increases in the order given above. Copyright © 2002 John Wiley & Sons, Ltd.
Effects of non‐ionic and mixed cationic–non‐ionic micelles on the rate of alkaline hydrolysis of phthalimide
Authors: Khan M. Niyaz , Ismail Emran 
Published: October 2002

AbstractPseudo‐first‐order rate constants (kobs) for the alkaline hydrolysis of phthalimide (PTH) show a monotonic decrease with the increase in [C16E20]T (total concentration of Brij 58) at constant [CH3CN] and [NaOH]. This micellar effect is explained in terms of the pseudophase model of micelles. The rate of hydrolysis of PTH in C16E20 micellar pseudophase appears to be negligible compared with that in the aqueous pseudophase. The values of kobs for C12E23 (Brij 35) show a sharp decrease at very low values of [C12E23]T followed by a very slow decrease with increase in [C12E23]T at relatively higher values of the latter. The rate of hydrolysis becomes too slow to monitor at [C12E23]T ≥0.04 M in the absence of cetyltrimethylammonium bromide (CTABr) and at [C12E23]T ≥0.05 M in the presence of 0.006–0.02 M CTABr at 0.02 M NaOH whereas such characteristic behavior is kinetically absent with C16E20. The values of kobs, obtained at different [NIS]T (where NIS represents C16E20 and C12E23) in the presence of a constant amount of CTABr, follow the empirical relationship kobs = (k0 + kK[NIS]T)/(1 + K[NIS]T) where k and K are empirical parameters. The values of k are only slightly affected whereas the values of K decrease with increase in [CTABr]T for the mixed C16E20–CTABr micellar system. The rate of hydrolysis of PTH at ≥0.01 M C12E23 and ≥0.01 M CTABr reveals the formation of phthalic anhydride whereas this was not observed in the mixed C16E20–CTABr micellar system under similar experimental conditions. Copyright © 2002 John Wiley & Sons, Ltd.
Thermal latency of novel chelating borate catalysts as latent catalysts for epoxy–phenolic resins
Authors: Goh Yoshiyuki , Iijima Takao , Tomoi Masao 
Published: October 2002

AbstractNovel quaternary ammonium bis(2‐oxybenzoyloxy)borate salts (1a–1c) or quaternary ammonium bis(1,2‐benzenedioxy)borate salts (2a and 2b) with tetra‐n‐butylammonium (TBA+), tetra‐n‐octylammonium (TOA+), or bis(triphenylphosphoranylidene)ammonium (PNP+) cations were synthesized as latent catalysts of epoxy/phenol–novolac resins by the complexation between boric acid and salicylic acid or catechol, followed by neutralization with quaternary ammonium hydroxide. Polyaddition reactions of diglycidyl ether of bisphenol A (DGEBA) and 4,4′‐bisphenol F (44BPF) or bisphenol F (BPF‐D) with the ammonium borates were investigated as model reactions of epoxy/phenol–novolac resin systems with respect to the thermal latency and storage stability of the catalyst. The polyaddition of DGEBA/44BPF with 1a–1c in diglyme at 150 °C for 6 h proceeded up to 85–96% conversions and gave polymers with number‐average molecular weights of 4180–10,500, whereas the polyaddition at 80 °C for 6 h gave less than 8% conversions. However, the polyaddition with 2a containing TBA+ cation proceeded to only a 32% conversion at 150 °C for 6 h in diglyme and to a 64% conversion even at 180 °C for 6 h in triglyme and only gave low molecular weight oligomers, and no reaction proceeded in the polyaddition at 80 °C. However, polyaddition with 2b containing PNP+ cation proceeded up to a 96% conversion at 150 °C for 6 h in diglyme and gave a higher molecular weight polymer with a number‐average molecular weight of 8050, whereas the polyaddition at 80 °C for 6 h gave only a 5% conversion. The catalytic activity of ammonium borates 1a–1c and 2a and 2b depended on the borate anion structure: 1a and 1c with bis(2‐oxybenzoyloxy)borate anion revealed higher activity than 2a and 2b with bis(1,2‐benzenedioxy)borate anion, respectively. In comparison with tetra‐n‐butylammonium bromide (TBAB) as a conventional ammonium salt or tetra‐n‐butylammonium tetrakis(benzoyloxy)borate (TBA‐TBB), 1a–1c and 2b revealed better thermal latency. The catalytic activity of ammonium borates also depended on the bulkiness of the ammonium cation, and the order of activity was 1c (PNP+) > 1b (TOA+) ≧ 1a (TBA+) and 2b (PNP+) > 2a (TBA+). The storage stability of DGEBA/BPF‐D with the ammonium borate catalysts 1a–1c and 2a and 2b in bulk at 40 °C was much better than that with TBAB and TBA‐TBB. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2702–2716, 2002
Synthesis and properties of crosslinked polyvinylformamide and polyvinylamine hydrogels in conjunction with silica particles
Authors: Meyer Torsten , Hellweg Thomas , Spange Stefan , Hesse Stephanie , Jäger Christian , Bellmann Cornelia 
Published: October 2002

AbstractPolyvinylamine hydrogels with silica particles encapsulated (PVAm/silica) were produced by a two‐step synthesis. In the first step, polyvinylformamide/silica (PVFA/silica) hybrids were synthesized from vinylformamide (VFA) and 1,3‐divinylimidazolidin‐2‐one (1,3‐bisvinylethyleneurea, BVU), as the crosslinker, by radical copolymerization in silica/water suspensions using different compositions of VFA/BVU. The target product PVAm/silica was obtained by acidic hydrolysis of the PVFA/silica hydrogels in a second step. The chemical structures of both hydrogels, PVFA/silica and PVAm/silica, respectively, were revealed by solid‐state 13C(1H) cross‐polarity/magic‐angle spinning NMR spectroscopy. Both hydrogels swelled significantly in water. The swelling capacity of the two systems was characterized by the correlation length ξ (or hydrodynamic blob size) of the network meshes with small‐angle neutron scattering experiments. ξ is significantly larger for PVAm/silica than for PVFA/silica, which corresponds to the observed higher swelling capacity of this polyelectrolyte material. Furthermore, the swelling behavior of the hybrid hydrogels was quantitatively described in terms of free swell capacity, centrifuge‐retention capacity, adsorption against pressure, and free swell rate as compared with values of the corresponding copolymer hydrogels. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3144–3152, 2002
Acoustic determination of polymer molecular weights and rotation times
Authors: Melzak Kathryn A. , Martin Fabrice , Newton Michael I. , Mchale Glen , Gizeli Electra 
Published: October 2002

AbstractAn acoustic waveguide device was shown to be sensitive to the molecular weight of poly(ethylene glycol) in solution over a molecular weight range determined by the operating frequency of the device. The acoustic device used generates a shear wave with displacement in the plane of the device surface and normal to the direction of propagation. Liquid over the device exhibits viscous coupling to the oscillating surface, affecting propagation of the acoustic wave. The propagation loss was shown to be directly proportional to the weight percentage of the solute. For a given weight percent of polymer in solution, the loss increased with increasing molecular weight until a maximum loss value was reached; this may be due to the fact that rotational times for polymer molecules increase with molecular weight until they reach a point at which the rotation is limited by the oscillation time on the device surface. The molecular weight at which the maximum loss value was attained was 10,000 g/mol for a device operating at 104 MHz and 3350 g/mol for a device operating at 331 MHz, implying a rotational time of 1 ns for each 2200 increase in molecular weight. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1490–1495, 2002
Thermal analysis and X‐ray scattering study of metallocene isotactic polypropylene prepared by partial melting
Authors: Dai Patrick S. , Cebe Peggy , Capel Malcolm 
Published: October 2002

AbstractIn this study, we examine the effects of heating, nucleation, cooling, and reheating on the thermal properties and structure of metallocene isotactic polypropylene (m‐iPP) that had been prepared initially in a standard state containing nearly equal amounts of the crystallographic α and γ phases. Heat treatment was achieved through partial melting and annealing by the heating of samples to self‐nucleation temperatures (Tn's) that spanned and exceeded the entire range of melting of the standard state, from 122 to 160 °C. The relative amounts of α and γ crystals are determined from the area under the unique wide‐angle X‐ray reflections. The lower and upper endotherms are caused by the melting of γ and α crystals, respectively. Four distinct regions of Tn were identified on the basis of the thermal and structural parameters of m‐iPP. In region I, Tn is below the peak melting temperature of the γ phase. Here, γ crystals are annealed and α crystals are barely affected by Tn. In region II, Tn is above the peak of the lower endotherm but below the peak of the upper endotherm. γ crystals melt, and α crystals anneal. In both regions I and II, the portion of the sample melted at Tn recrystallizes epitaxially with existing parent α lamellae as the substrates, and the amount of α always exceeds the amount of γ. In region III, Tn is above the peak of the upper endotherm, and all γ crystals and some or all α crystals are melted at Tn. The number of α‐crystal nuclei steadily decreases as Tn increases, causing systematic depression of the crystallization and melting temperatures seen during cooling. Finally, in region IV, Tn exceeds the upper endotherm, and only small self‐nuclei or heterogeneous nuclei remain. Recrystallization is now suppressed to lower temperatures. For regions III and IV, a crossover behavior in the relative amounts of α and γ is observed during cooling from Tn. Because of the effective nucleating ability of α toward γ, as the temperature drops, the amount of γ increases and then exceeds the amount of α. With subsequent reheating, the reverse crossover occurs because of the lower melting point of γ. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1644–1660, 2002
Lamellar morphology and equilibrium melting temperature of syndiotactic polystyrene in β‐crystalline form
Authors: Wang Chi , Cheng Yong‐Wen , Hsu Yao‐Chung , Lin Tsang‐Lang 
Published: October 2002

AbstractLamellar morphology and thickness of syndiotactic polystyrene (sPS) samples melt‐crystallized at various temperatures were probed using transmission electron microscopy (TEM) and small‐angle X‐ray scattering (SAXS). In addition, the melting temperature and enthalpy of the crystallized samples were characterized with differential scanning calorimetry. Under appropriate thermal treatments, all the samples investigated in this study were crystallized into β′ crystal modification, as revealed by wide‐angle X‐ray diffraction. From the SAXS intensity profiles, a scattering peak (or shoulder) associated with lamellar features as well as the presence of anomalous scattering at the zero‐scattering vector were evidently observed. The peculiar zero‐angle scattering was successfully described by the Debye–Bueche model, and subtraction of its contribution from the raw intensity profiles was carried out to deduce the intensity profile merely associated with the lamellar feature. The lamellar thickness obtained from Lorentz‐corrected intensity profiles in this manner agrees with that measured from the TEM images, provided that the two‐phase model is applied. On the basis of the Gibbs–Thomson equation, the modest estimations of equilibrium melting temperature and the surface free energy of the fold lamellar surface are 292.7 ± 2.7 °C and 20.2 ± 2.6 erg/cm2, respectively, when lamellar thicknesses measured by TEM are applied. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1626–1636, 2002