bluuebunny/crossref_metadata_2025 huggingface dataset:
Reader beware: diabetes advice on the web
Authors: Kelly William , Connolly Vincent , Bilous Rudolf , Stewart Amanda , Nag Satyajit , Bowes Daniel , Loader Brian , Muncer Steve
Published: October 2002

In recent years there has been a significant expansion of information and advice for people with diabetes available on the Internet. Interestingly much of this is provided by lay people, who often have diabetes themselves. Consequently we decided to critically evaluate the quality of non‐professional advice available on the Internet for people with diabetes. This was undertaken by identifying a dedicated diabetes newsgroup, which was analysed by a panel of specialist diabetologists who assessed the quality of postings and responses using a six point classification. Each message was rated independently by each of the five panel members and scores were compared for reliability of judgement. From the newsgroup used mainly by non‐professionals 61 start messages comprised 54 questions, six statements and one commercial proposition. Sixteen questions related to diet, nine to glycaemic control and blood tests, ten to tablets and insulin, eight to complications, and there were 18 others. 61 start messages were categorised as four excellent, 24 less good—some details, 17 poor—little detail, 17 vague, but none were misleading or incomprehensible. After 5 days 61 messages had generated 242 responses, which were assessed as 13 evidence based excellent, 60 accepted wisdom, 137 personal opinion anecdote, 26 misleading or irrelevant, one false and five open to misinterpretation. There were 146 respondents (30 more than once), range of replies 1–15, identified as a doctor in four instances, but usually patient, relative or unknown. Newsgroups such as the one we analysed are clearly a valuable forum for persons with diabetes to interact with each other, share experiences and provide social support. For the most part the level of understanding about the condition was quite extensive, with the debate being largely technical in nature. Of the 242 responses, only six were regarded as either false or possibly dangerous. This raises important questions about how to ensure that the information provided on the Internet for persons with diabetes is accurate, sensible, evidence based and easily accessible. Copyright © 2002 John Wiley & Sons, Ltd.
An evaluation of diabetic care in registered nursing homes
Authors: Duffy Una , Craig Michael
Published: October 2002

This study examines current clinical practice in relationship to the care of diabetic patients in Registered Nursing Homes in Argyll and Clyde NHS Board and training needs of staff. The prevalence of diabetes was found to be 6.5% (95% CI 4.7–8.3) with 12 having type 1 and 82 having type 2 diabetes. This comprised 58 women and 42 men with a mean age of 79 years. The mean number of patients per home was 2.6 (95% CI 1.9–3.4) with a range of 0–22. Eighty‐one patients were medically cared for solely by general practice. Seventeen homes screened new patients on admission for diabetes using a variety of methods; only six homes tested blood glucose levels as part of their screening programme. Ninety‐one per cent of the sample were receiving regular blood glucose monitoring; of the patients treated with insulin 50% were having blood glucose monitoring a minimum of once per day. Forty‐seven per cent had annual retinopathy screening, with 62% being undertaken by an accredited optometrist. Ninety‐one per cent of patients had been treated by a chiropodist in the previous 12 months. A dietician had assessed 13% of patients in the previous 12 months. There was a positive response to further education on diabetes, with particular needs expressed for staff training, including blood monitoring and screening. This study has formed the basis for the development of nursing guidelines for diabetes in nursing homes and the development of an educational programme. Copyright © 2002 John Wiley & Sons, Ltd.
The need for a national infrastructure to improve the rational use of therapeutics
Authors: Califf Robert M.
Published: October 2002

The current medical care environment has created expectations that exceed its capabilities, one effect of which has been an increasing awareness of lapses in the quality of healthcare, including medical errors. As more new therapies reach clinical application, the expectations on the part of the public are unlikely to lessen, and yet the ability to assure patients that the benefits of these therapies are known, and that they are without serious side‐effects or untoward consequences, eludes the healthcare system. Based on initial experience with a new federal program, the Centers for Education and Research on Therapeutics (CERTs), we propose a national approach to therapeutics education and research, through a public–private partnership that involves academic medical centers, the federal government, industry, and the public. Through a concerted approach, we believe that significant gaps in our understanding of key issues in therapeutics and our ability to educate practitioners, policy makers, and consumers can be significantly enhanced in a manner that could not be achieved without a coordinated approach. Copyright © 2002 John Wiley & Sons, Ltd.
A pharmacoeconomic comparison of misoprostol/diclofenac with diclofenac
Authors: Morant S. V. , Shield Michael J. , Davey P. G. , MacDonald T. M.
Published: October 2002

Objectives

To estimate the economic impact of misoprostol/diclofenac in a fixed combination tablet compared with diclofenac.

Design

Cohort 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.

Setting

The population of Tayside, Scotland.

Subjects

Subjects aged 20 years and over who received misoprostol/diclofenac or any other NSAID between January 1989 and 31 December 1995.

Main outcome measures

Total 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.

Results

The 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.

Conclusion

Use 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

A 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

We 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

Solvolytic 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

Aqueous 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

The 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

Several 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

Tertiary 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

Modeling 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

The 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

Pseudo‐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

Novel 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

Polyvinylamine 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

An 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

In 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

Lamellar 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
Phase behavior and crystallization of a poly(ethylene oxide)/cellulose acetate butyrate blend
Authors: Park Min Soo , Kim Jin Kon
Published: October 2002

The phase behavior of a partially miscible blend of poly(ethylene oxide) (PEO) and cellulose acetate butyrate (CAB) and the crystalline microstructure of PEO in the blend were studied with differential scanning calorimetry (DSC), optical microscopy, and synchrotron small‐angle X‐ray scattering (SAXS) methods. PEO/CAB showed a lower critical solution temperature (LCST) of 168 °C at the critical composition of PEO of 60 wt %. All blend compositions showed a single glass‐transition temperature (Tg) when they were prepared at temperatures lower than the LCST. However, with increasing CAB content, Tg of the blend changed abruptly at 70 wt % CAB; that is, a cusp existed. Below 70 wt % CAB, the change in Tg with blend composition was predicted by the Brau–Kovacs equation, whereas this change was predicted by the Fox equation at higher CAB contents. A gradual but small depression of the melting point of PEO in the blend with an increasing amount of CAB suggested that the PEO/CAB blends exhibited a weak intermolecular interaction. From DSC and SAXS experiments, it was found that amorphous CAB was incorporated into the interlamellar region of PEO for blends with less than 20 wt % CAB, whereas it was segregated to exist in the interfibrillar region in PEO for other blends with larger amounts of CAB. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1673–1681, 2002
Melt‐state polymer chain dimensions as a function of temperature
Authors: Krishnamoorti Ramanan , Graessley William W. , Zirkel Achim , Richter Dieter , Hadjichristidis Nikos , Fetters Lewis J. , Lohse David J.
Published: October 2002

The unperturbed chain dimensions (〈R2〉o/M) of cis/trans‐1,4‐polyisoprene, a near‐atactic poly(methyl methacrylate), and atactic polyolefins were measured as a function of temperature in the melt state via small‐angle neutron scattering (SANS). The polyolefinic materials were derived from polydienes or polystyrene via hydrogenation or deuteration and represent structures not encountered commercially. The parent polymers were prepared via lithium‐based anionic polymerizations in cyclohexane with, in some cases, a polymer microstructure modifier present. The polyolefins retained the near‐monodisperse molecular weight distributions exhibited by the precursor materials. The melt SANS‐based chain dimension data allowed the evaluation of the temperature coefficients [dln 〈R2〉o/dT(κ)] for these polymers. The evaluated polymers obeyed the packing length (p)‐based expressions of the plateau modulus, G = kT/np3 (MPa), and the entanglement molecular weight, Me = ρNanp3 (g mol−1), where nt denotes the number (∼21) of entanglement strands in a cube with the dimensions of the reptation tube diameter (dt) and ρ is the chain density. The product np3 is the displaced volume (Ve) of an entanglement that is also expressible as pd or kT/G. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1768–1776, 2002
Improved numerical algorithm for exploring block copolymer mesophases
Authors: Rasmussen K. Ø. , Kalosakas G.
Published: October 2002

We present an improved algorithm of the self‐consistent mean‐field implementation that has been recently proposed for the calculation of block copolymer self‐assembly. Without requiring prior knowledge of the symmetry of the mesophase segregation, the algorithm is numerically stable and significantly faster than previously proposed methods. These advantages provide a valuable tool for combinatorial screening of novel stable and metastable structural phases of block copolymers. We apply the method and demonstrate complex mesophases in linear, asymmetric triblock copolymer melts. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1777–1783, 2002
Ductile–brittle‐transition phenomenon in polypropylene/ethylene‐propylene‐diene rubber blends obtained by dynamic packing injection molding: A new understanding of the rubber‐toughening mechanism
Authors: Wang Yong , Fu Qiang , Li Qijun , Zhang Gong , Shen Kaizhi , Wang Yu‐Zhong
Published: October 2002

For a more complete understanding of the toughening mechanism of polypropylene (PP)/ethylene‐propylene‐diene rubber (EPDM) blends, dynamic packing injection molding was used to control the phase morphology and rubber particle orientation in the matrix. The relative impact strength of the blends increased at low EPDM contents, and then a definite ductile–brittle (D–B) transition was observed when the EPDM content reached 25 wt %, at which point blends should fail in the ductile mode with conventional molding. Wide‐angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) were used to investigate the shear‐induced crystal structure, morphology, orientation, and phase separation of the blends. WAXD results showed that the observed D–B transition took place mainly for a constant crystal structure (α form). Also, no remarkable changes in the crystallinity and melting point of PP were observed by DSC. The highly oriented and elongated rubber particles were seen via SEM at high EPDM contents. Our results suggest that Wu's criterion is no longer valid when dispersed rubber particles are elongated and oriented. The possible fracture mechanism is discussed on the basis of the stress concentration in a filler‐dispersed matrix. It can be concluded that not only the interparticle distance but also the stress fields around individual particles play an important role in polymer toughening. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2086–2097, 2002
Ultrafine fibrous cellulose membranes from electrospinning of cellulose acetate
Authors: Liu Haiqing , Hsieh You‐Lo
Published: October 2002

Three solvents, that is, acetone, acetic acid, and dimethylacetamide (DMAc), with a range of solubility parameter δ, surface tension γ, viscosity η and boiling temperature were used to generate mixtures for electrospinning cellulose acetate (CA) (degree of substitution, DS = 2.45). Although none of these solvents alone enables continuous formation of fibers, mixing DMAc with either acetone or acetic acid produced suitable solvent systems. The 2:1 acetone:DMAc mixture is the most versatile mixture because it allows CA in the 12.5–20% concentration range to be continuously electrospun into fibrous membranes. These CA solutions have η between 1.2 and 10.2 poise and γ around 26 dyne/cm and produce smooth fibers with diameters from 100 nm to ∼1 μm. Fiber sizes generally decrease with decreasing CA concentrations. The nature of the collectors affects the morphology as well as packing of fibers. Fibers collected on paper have more uniform sizes, smooth surfaces, and fewer defects, whereas fibers collected on water are more varied in size. Electrically conductive solid collectors, such as Al foil and water, favor more tightly packed and less porous membranes. Porous collectors, like paper and copper mesh, produce highly porous membranes. The pores in membranes collected on the Al foil and paper are much better interconnected in the planar directions than those in membranes collected on water. There is evidence that electrospinning induces order in the fibers. Deacetylation of CA membranes is more efficient and complete in NaOH/ethanol than in aqueous NaOH, producing DS values between 0.15 and 2.33 without altering fiber surfaces, packing, or organization. The fully regenerated cellulose membranes are similarly hydrophilic as commodity cellulose fibrous matrices but absorb nearly 10 times as much water. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2119–2129, 2002
Prostate cancer and health‐related quality of life: a review of the literature
Authors: Eton David T. , Lepore Stephen J.
Published: October 2002

With the established effectiveness of diverse treatments for prostate cancer, identification of the physical and psychosocial consequences of the disease and various treatments becomes critical. We review the literature on the effects of prostate cancer and its treatment on health‐related quality of life (HRQoL). Studies show that prostate cancer and its treatment affect both disease‐specific HRQoL (i.e. urinary, sexual, and bowel function) as well as general HRQoL (i.e. energy/vitality, performance in physical and social roles). Yet, these effects appear to differ across stage of disease and type of treatment. We outline evidence from three sources: (1) studies that compare men with the disease with an age‐matched sample of men without the disease, (2) studies that assess men with the disease across time, and (3) cross‐sectional studies that highlight predictors of HRQoL. Future research directions are discussed. Copyright © 2002 John Wiley & Sons, Ltd.
Foreign body aspiration: What is the outcome?
Authors: Karakoç Fazilet , Karadağ Bülent , Akbenlioğlu Cengiz , Ersu Refika , Yıldızeli Bedrettin , Yüksel Mustafa , Dağlı Elif
Published: October 2002

Undiagnosed and retained foreign bodies may result in serious complications such as pneumonia, atelectasis, or bronchiectasis. We reviewed a total of 174 children with foreign body aspiration (FBA). Clinical, radiological, and bronchoscopic findings of these patients were evaluated according to the nature of foreign body and elapsed time from aspiration to diagnosis.

Significant differences were noted between patients with organic and inorganic FBA in terms of clinical and radiological findings. Cough, recurrent pneumonia, and fever were the most common presenting symptoms in patients with delayed diagnosis. Long‐term follow‐up was available for 110 patients for a mean duration of 37.8 ± 23.7 months (range, 1–88 months). We evaluated the course of recovery after bronchoscopic removal. Organic FBA was of comparable duration as for inorganic FBA, and prolonged follow‐up was associated with increased risk of persistent symptoms and bronchiectasis (P < 0.001). The risk of long‐term complications increased with increasing elapsed time from aspiration to diagnosis; complications were as high as 60% in children who were diagnosed 30 days after FBA (P = 0.0035). Bronchiectasis was a major complication, found in 25% of patients whose diagnosis was delayed by more than 30 days (P = 0.0001). Three patients with bronchiectasis underwent lobectomy. Patients with persistent asthma‐like symptoms such as cough and wheezing required treatment with inhaled corticosteroids and bronchodilators. The positive response to this treatment was thought to be a confirmation of the development of transient bronchial hyperresponsiveness induced by foreign bodies.

We conclude that timely diagnosis and appropriate treatment of FBA is important to prevent long‐term complications in affected children. Pediatr Pulmonol. 2002; 34:30–36. © 2002 Wiley‐Liss, Inc.
Beclomethasone dipropionate and salbutamol by metered dose inhaler in infants and small children with recurrent wheezing
Authors: Barrueto Luis , Mallol Javier , Figueroa Luis
Published: October 2002

The efficacy of beclomethasone dipropionate (BDP) to control respiratory symptoms was evaluated in 31 children under age 2 years with recurrent wheezing. The study was conducted in a double‐blind, parallel, and placebo‐controlled fashion. The two study groups received either salbutamol plus BDP 200 μg bid by metered dose inhaler (MDI) with a spacer, or salbutamol MDI plus a placebo. Inhaled corticosteroid (IC) and placebo were administered for 8 weeks. Patients were seen every 2 weeks as outpatients, and their progress was evaluated by clinical examination and a daily symptom score card.

At the end of the study, patients in both groups had significantly decreased symptoms. No significant difference was found between BDP and placebo groups regarding clinical score, number of salbutamol doses, sleep disturbances, number of symptom‐free days, feelings of insecurity of mothers regarding the infants' life due to wheezing, and mothers' perceptions of progress in their infants' respiratory symptoms.

We conclude that salbutamol plus 200 μg bid of BDP inhaled from an MDI with a spacer for 8 weeks is no better than salbutamol alone for decreasing recurrent wheezing in small children under age 24 months. Pediatr Pulmonol. 2002; 34:52–57. © 2002 Wiley‐Liss, Inc.
Are tidal volume measurements in neonatal pressure‐controlled ventilation accurate?
Authors: Chow Lily C. , Vanderhal Andre , Raber Jorge , Sola Augusto
Published: October 2002

Bedside pulmonary mechanics monitors (PMM) have become useful in ventilatory management in neonates. These monitors are used more frequently due to recent improvements in data‐processing capabilities. PMM devices are often part of the ventilator or are separate units. The accuracy and reliability of these systems have not been carefully evaluated.

We compared a single ventilatory parameter, tidal volume (Vt), as measured by several systems. We looked at two freestanding PMMs: the Ventrak Respiratory Monitoring System (Novametrix, Wallingford, CT) and the Bicore CP‐100 Neonatal Pulmonary Monitor (Allied Health Care Products, Riverside, CA), and three ventilators with built‐in PMM: the VIP Bird Ventilator (Bird Products Corp., Palm Springs, CA), Siemens Servo 300A (Siemens‐Elema AB, Solna, Sweden), and Drager Babylog 8000 (Drager, Inc., Chantilly, VA). A calibrated syringe (Hans Rudolph, Inc., Kansas City, MO) was used to deliver tidal volumes of 4, 10, and 20 mL to each ventilator system coupled with a freestanding PMM. After achieving steady state, six consecutive Vt readings were taken simultaneously from the freestanding PMM and each ventilator. In a second portion of the bench study, we used pressure‐control ventilation and measured exhaled tidal volume (Vte) while ventilating a Bear Test Lung with the same three ventilators. We adjusted peak inspiratory pressure (PIP) under controlled conditions to achieve the three different targeted tidal volumes on the paired freestanding PMM. Again, six Vte measurements were recorded for each tidal volume. Means and standard deviations were calculated.

The percentage difference in measurement of Vt delivered by calibrated syringe varied greatly, with the greatest discrepancy seen in the smallest tidal volumes, by up to 28%. In pressure control mode, Vte as measured by the Siemens was significantly overestimated by 20–95%, with the biggest discrepancy at the smallest Vte, particularly when paired with the Bicore PMM. Vte, as measured by the VIP Bird and Drager paired with the Ventrak PMM, had a tendency to underestimate Vt by up to 25% at the smallest Vte. However, when paired with the Bicore PMM, these same two ventilators read over target by up to 18%.

Under controlled laboratory conditions, we demonstrated that true delivered Vte, as measured by the three ventilators and two freestanding PMM, differed markedly. In general, decreasing dynamic compliance of the tubing was not associated with greater inaccuracy in Vte measurements. Pediatr Pulmonol. 2002; 34:196–202. © 2002 Wiley‐Liss, Inc.
Sleep and breathing in Prader‐Willi syndrome
Authors: Nixon Gillian M. , Brouillette Robert T.
Published: October 2002

Prader‐Willi syndrome (PWS) is a genetic disorder, with hypotonia being the predominant feature in infancy, and developmental delay, obesity, and behavioral problems becoming more prominent in childhood and adolescence. Children with this disorder frequently suffer from excessive daytime sleepiness and have a primary abnormality of the circadian rhythm of rapid eye movement sleep. They also have primary abnormal ventilatory responses to hypoxia and hypercapnia, and these abnormalities may be exacerbated by obesity. Children with PWS are at risk of a variety of abnormalities of breathing during sleep, including obstructive sleep apnea and sleep‐related alveolar hypoventilation. Clinical evaluation should include a careful history of sleep‐related symptoms and assessment of the upper airway and lung function. Polysomnography should be considered for those with symptoms suggestive of sleep‐disordered breathing. Treatment options depend on the underlying problem, but may include behavioral interventions, weight control, adenotonsillectomy, and nocturnal ventilation. Pediatr Pulmonol. 2002; 34:209–217. © 2002 Wiley‐Liss, Inc.
Scoring residue conservation
Authors: Valdar William S.J.
Published: October 2002

The importance of a residue for maintaining the structure and function of a protein can usually be inferred from how conserved it appears in a multiple sequence alignment of that protein and its homologues. A reliable metric for quantifying residue conservation is desirable. Over the last two decades many such scores have been proposed, but none has emerged as a generally accepted standard. This work surveys the range of scores that biologists, biochemists, and, more recently, bioinformatics workers have developed, and reviews the intrinsic problems associated with developing and evaluating such a score. A general formula is proposed that may be used to compare the properties of different particular conservation scores or as a measure of conservation in its own right. Proteins 2002;48:227–241. © 2002 Wiley‐Liss, Inc.
Thermal folding and mechanical unfolding pathways of protein secondary structures
Authors: Cieplak Marek , Hoang Trinh Xuan , Robbins Mark O.
Published: October 2002

Mechanical stretching of secondary structures is studied through molecular dynamics simulations of a Go‐like model. Force versus displacement curves are studied as a function of the stiffness and velocity of the pulling device. The succession of stretching events, as measured by the order in which contacts are ruptured, is compared to the sequencing of events during thermal folding and unfolding. Opposite cross‐correlations are found for an α‐helix and a β‐hairpin structure. In a tandem of two α‐helices, the two constituent helices unravel nearly simultaneously. A simple condition for simultaneous versus sequential unraveling of repeat units is presented. Proteins 2002;49:104–113. © 2002 Wiley‐Liss, Inc.
Conformational states of the glucocorticoid receptor DNA‐binding domain from molecular dynamics simulations
Authors: Bredenberg Johan , Nilsson Lennart
Published: October 2002

Molecular dynamics simulations (MD) have been performed on variant crystal and NMR‐derived structures of the glucocorticoid receptor DNA‐binding domain (GR DBD). A loop region five residues long, the so‐called D‐box, exhibits significant flexibility, and transient perturbations of the tetrahedral geometry of two structurally important Cys4 zinc finger are seen, coupled to conformational changes in the D‐box. In some cases, one of the Cys ligands to zinc exchanges with water, although no global distortion of the protein structure is observed. Thus, from MD simulation, dynamics of the D‐box could partly be explained by solvent effects in conjunction with structural reformation of the zinc finger. Proteins 2002;49:24–36. © 2002 Wiley‐Liss, Inc.