bluuebunny/crossref_metadata_2025_split huggingface dataset:
The population risk of fractures attributable to oral corticosteroids
Authors: Donnan Peter T. , Libby Gillian , Boyter Anne C. , Thompson Philip 
Published: January 2005

AbstractPurposePrevious studies have indicated a relationship between oral corticosteroid use and the risk of fracture, although without population‐based comparators or exact dose information. The aim was to estimate the relative and population attributable risk (PAR) of admission for non‐traumatic fracture among users of corticosteroids.MethodsThe design was a retrospective cohort study of the population of Tayside, Scotland aged 18 or over and resident between 1 January 1993 and 31 January 1997 (n = 280 645). Subjects included were those who redeemed one or more prescriptions for oral corticosteroids compared with those not prescribed corticosteroids (oral or inhaled) in the population. The main outcome measure was the PAR and relative risk of hospital admissions for non‐traumatic fracture.ResultsApproximately 7.5% of the population received prescriptions for oral corticosteroids. There was a significantly higher risk of fracture in the oral corticosteroid cohort when exposed to drugs compared with the general population (RR = 1.90, 95%CI 1.68, 2.16), after adjustment. Women were at higher risk than men, especially for vertebral fractures (RR = 5.19, 95%CI 2.95, 9.16). Previous fracture, Parkinsonian and anti‐epileptic medication were significantly associated with higher risk, while HRT, NSAIDS and statins were associated with lower risk. An estimate of one in six vertebral and 1 in 13 non‐vertebral fractures could be due to oral corticosteroid use in the population.ConclusionsThe important public health impact of oral corticosteroids, especially in women needs to be addressed. Greater use of medication to ameliorate the adverse effects of these widely‐used drugs is advocated. Copyright © 2005 John Wiley & Sons, Ltd.
Wheezing lower respiratory disease and vaccination of full‐term infants
Authors: Mullooly John P. , Pearson John , Drew Lois , Schuler Roberleigh , Maher Julie , Gargiullo Paul , DeStefano Frank , Chen Robert 
Published: January 2005

AbstractPurposeThere have been speculations that increases in vaccinations have caused recent increases in wheezing lower respiratory disease during infancy. We assess possible associations between vaccines and incidence of wheezing in full‐term infants.MethodsWe conducted a matched case–control study of full‐term infants born into the Kaiser Permanente Northwest health plan during 1991–1994 and continuously enrolled for at least 12 months (n = 1366 case–control pairs). Potential cases of wheeze were ascertained from medical care databases and verified by chart review. Vaccinations, demographic factors, and wheeze risk factors were abstracted from charts. Adjusted relative risks of first onset of wheeze during post‐vaccination exposure windows were estimated by conditional logistic regression. We also conducted case‐series analyses of wheeze onsets.ResultsWe found no evidence that risk of wheeze during infancy is associated with recency of vaccination with whole‐cell pertussis (DTP), hepatitis b (HBV), Haemophilus influenzae type b (HIB), oral polio (OPV), or measles, mumps and rubella (MMR) vaccines. We also found no evidence that risk of first wheeze is associated with exposure to HBV or MMR.ConclusionsRecent increases in wheezing during infancy do not appear to be related to increases in vaccinations of full‐term infants. Published in 2002 by John Wiley & Sons, Ltd.
Should cases with a ‘known’ cause of their disease be excluded from study? (Commentary)
Authors: Rothman K. J. , Ray W. 
Published: January 2005

AbstractAssigning a cause to an individual event is a natural impulse. This impulse sometimes finds its way into epidemiologic research, if researchers assign a specific cause to some cases of a disease under study. In epidemiologic studies of drug effects, assigning a cause to specific cases is often used as a reason to exclude these cases from cohort or case–control studies, because the disease in these cases is thought to be the result of a ‘known cause’. These exclusions are invalid. It is always valid, however, to exclude all subjects with ‘known’ causes from a study, cases from the numerator and the people or person‐time at risk from the denominator (or from the control series in a case–control study). If the exclusions from the denominator would be negligibly small or the relative number of excluded cases with ‘known’ causes is small, then the exclusion of just the cases with ‘known’ causes will introduce little bias. Copyright © 2002 John Wiley & Sons, Ltd.
Investigation into the solution properties of hyperbranched polymer
Authors: Xu Min , Yan Xiaohu , Cheng Rongshi , Yu Xuehai 
Published: January 2005

AbstractThe solution properties of hydroxyl terminated hyperbranched aliphatic polyesters and their acetyl derivatives have been studied by measuring viscosity parameters. The polarity of terminated groups of molecules is the most important factor affecting their properties. The intrinsic viscosity [η] cannot reflect the real monomolecular hydrodynamic volume of hydroxyl group‐terminated hyperbranched polymer due to the strong intermolecular forces which lead to the formation of stable clusters. The intermolecular association constant KM depends not only on molecular weight, but also on the polarity of end‐groups. However, the dynamic contact concentration CS can be determined accurately from reduced viscosity versus concentration plots. The reason why the intrinsic viscosity does not change linearly with the generation of the hyperbranched aliphatic polyesters is explained using ‘free‐draining’ and ‘non‐draining’ models.© 2001 Society of Chemical Industry
Removal of N‐methylpyrrolidone hydrogen‐bonded to polyaniline free‐standing films by protonation–deprotonation cycles or thermal heating
Authors: Ponzio Eduardo A , Echevarria Ricardo , Morales Gustavo M , Barbero Cesar 
Published: January 2005

AbstractFree‐standing films of polyaniline (PANI), in an emeraldine base state, prepared by evaporation of polymer solutions in N‐methylpyrrolidone (NMP) retain solvent even under dynamic vacuum drying as indicated by transmission Fourier transform infrared (FTIR) spectroscopy, where a band at 1670 cm−1 is clearly observed. Upon protonation–deprotonation cycles in aqueous media the weight of the dry base film decreases indicating gradual loss of NMP. Transmission FTIR spectra shows also the washing out of NMP with a clear decrease in intensity of the hydrogen‐bonded >CO stretching band (1670 cm−1) of NMP. During this process the bands between 3500 and 3200 cm−1, assigned to >NH stretching in the PANI backbone, change intensity suggesting that intermolecular hydrogen‐bonded >NH, with carbonyl oxygen of NMP, is replaced by free >NH. This is clear evidence of specific interaction of NMP with the emeraldine base. A similar loss of NMP is observed during heating but evidence of polymer degradation is also present. A mechanism is proposed to account for the loss of hydrogen‐bonding ability upon protonation which requires delocalization of the radical cations in the protonated films.© 2001 Society of Chemical Industry
A simple method for determining light transmittance of polymer films used for packaging foods
Authors: Turhan K N , Şahbaz F 
Published: January 2005

AbstractSensitive components of food may undergo degradation reactions when subjected to light. The packaging of the food may slow down such reactions by absorbing and reflecting a fraction of the incident light. Riboflavin is a light‐sensitive vitamin and undergoes first‐order degradation when subjected to visible light. Rate constants of this reaction were evaluated under 20 W coolwhite light at pH = 9.0 at 25 °C, with no light shielding or by shielding the light with methylcellulose films. Based on this photodegradation reaction, a new model was proposed to define percentage light transmittance of methylcellulose films. Depending on composition, the percentage transmittance was in the range 66–96%. Variation of light transmittance was explained in terms of solubility and crystallinity.© 2001 Society of Chemical Industry
High oil‐absorptive composites based on 4‐tert‐butylstyrene‐EPDM‐divinylbenzene graft polymer
Authors: Zhou Mei Hua , Cho Won‐Jei 
Published: January 2005

Abstract4‐tert‐Butylstyrene‐EPDM‐divinylbenzene graft polymer (PBED) was prepared by graft crosslinking polymerization in toluene using BPO as an initiator. Gel and sol of PBED were isolated by extraction with tetrahydrofuran (THF). Sol PBED can be reused as oil absorbent through cross‐linking by ultraviolet irradiation. After swelling in oil, crosslinked polymers have poor gel strength to be taken out of oil wholly at high absorbency, although they possess strong mechanical strength in their dry states. As known, composite technique is one of the useful methods for material reinforcement. Fibres, sponges and non‐woven fabrics were used as reinforcers or supporters in this work. Oil absorbency was measured by method ASTM (F726‐81) and swelling kinetics of the composite was evaluated by an experimental equation. The gel strength parameter S, the relaxation exponent n, and the fractal dimension df of polymer and some composites in pseudo‐critical gel state were determined from oscillatory shear measurements by a dynamic rheometer. Mechanical properties and the morphologies of some composites were measured with a tensile tester and scanning electron microscopy, respectively.© 2001 Society of Chemical Industry
Architecture of nanostructured polymers by segregated domain crosslinking of block‐graft copolymer micelles
Authors: Ishizu Koji , Hosokawa Takafumi 
Published: January 2005

AbstractPolystyrene‐block‐polyisoprene (PS‐block‐PI; high 3,4‐structure) diblock copolymer was prepared by living anionic polymerization. For transfer into a reactive intermediate, the hydroxylation of the double bonds of PI block was achieved by hydroboration, followed by oxidation. Esterification of the hydroxy‐derivative with stearoyl chloride or decanoyl chloride resulted in block‐graft copolymers composed of PS (flexible chain)‐grafted long alkane (stretched chains). After partial chloromethylation of PS block copolymer, photofunctional N,N‐diethyldithiocarbamate (DC) groups were introduced into such pendant sites by reaction with the corresponding sodium salt. We studied the self‐assemblies of photofunctional block‐graft copolymers in a selective solvent, such as heptane, and constructed nanostructured polymers by crosslinking PS cores under UV irradiation.© 2001 Society of Chemical Industry
Synthesis and characterization of thermoplastic poly(ester–siloxane)s
Authors: Antic Vesna V , Balaban Milica R , Djonlagic Jasna 
Published: January 2005

AbstractTwo series of thermoplastic poly(ester–siloxane)s, based on poly(dimethylsiloxane) (PDMS) as the soft segment and poly(butylene terephthalate) as the hard segment, were synthesized by two‐step catalyzed transesterification reactions in the melt. Incorporation of soft poly(dimethylsiloxane) segments into the copolyester backbone was accomplished in two different ways. The first series was prepared based on dimethyl terephthalate, 1,4‐butanediol and silanol‐terminated poly(dimethylsiloxane) (PDMS‐OH). For the second series, the PDMS‐OH was replaced by methyl diesters of carboxypropyl‐terminated poly(dimethylsiloxane)s. The syntheses were optimized in terms of both the concentration of catalyst, tetra‐n‐butyl‐titanate (Ti(OBu)4), and stabilizer, N,N′‐diphenyl‐p‐phenylene‐diamine, as well as the reaction time. The reactions were followed by measuring the inherent viscosities of the reaction mixture. The molecular structures of the synthesized poly(ester–siloxane)s were verified by 1H NMR spectroscopy, while their thermal properties were investigated using differential scanning calorimetry.© 2001 Society of Chemical Industry
Effect of synthetic sodium aluminium silicate on the properties of nylon 6
Authors: Upadhyay R D , Kale D D 
Published: January 2005

AbstractCompounds were prepared from nylon 6 and synthetic sodium aluminium silicate (SSAS), varying the concentration of SSAS, up to 15% (wt/wt). Mechanical and rheological properties as well as optical properties were measured. There was a substantial increase in flexural modulus and flexural strength with added SSAS. However, the percentage elongation at break decreased rapidly with increasing amount of SSAS. All the compositions had much higher shear and extensional viscosity than nylon 6 alone. At lower concentrations, the filler induced dull yellow appearance, which disappeared as the concentration of SSAS increased.© 2001 Society of Chemical Industry
Copolymerization of carbon monoxide with exo‐methylenecycloalkane and dienes: synthesis of functionalized aliphatic polyketones
Authors: Kettunen Mika , Abu‐Surrah Adnan S , Repo Timo , Leskelä Markku 
Published: January 2005

AbstractSynthesis of functional aliphatic polyketones was achieved by co‐ and terpolymerization of the strained exo‐methylenecycloalkane, methylenecyclopropane (MCP), and also the dienes 1,5‐hexadiene, 1,7‐octadiene and 1,6‐heptadien‐4‐ol, with carbon monoxide and propene, using the dicationic palladium(II) phosphine complex [Pd(dppp) (NCCH3)2](BF4)2 (I) (dppp is 1,3‐bis(diphenyl‐phosphino)propane) as the catalyst precursor. The resulting MCP/CO copolymer contains both ring‐opened and cyclic microstructures. Ring‐opening copolymerization yields exo‐methylene functionalized polyketone. In contrast to hexadiene/carbon monoxide copolymer (Hx/CO), no ring structures were observed in the alternating octadiene/carbon monoxide (Oc/CO) and heptadien‐4‐ol/carbon monoxide (Hp‐ol/CO) copolymers. The remaining double bonds were left intact to yield polymers with olefinic functionalities in the side chains.© 2001 Society of Chemical Industry
Synthesis and characterization of new 4‐tolyldiphenylamine derivatives for hole transporting polymers
Authors: Strzelec Krzysztof , Tsukamoto Nami , Kook Ha Jae , Sato Hisaya 
Published: January 2005

AbstractNew hole transport polymers have been synthesized by condensation polymerization of 4‐tolyldiphenylamine (TDPA) with various types of aldehyde. The reaction conditions have been investigated to yield polymers with high molecular weight. It is found that the molecular weight and yield of the TDPA–aldehyde polymers strongly depend on the electron donor–acceptor nature of the substituent on the aromatic ring of the aldehyde monomer. Structural characterization by 1H NMR spectroscopy shows that the addition condensation reaction occurs exclusively at the para position of TDPA. The electrochemical and optical properties of polymers have been investigated by cyclic voltammetry and UV–vis spectroscopy. Cyclic voltammograms of all polymers show well‐defined pairs of reduction and oxidation peaks, indicating that the polymers are electrochemically active. All polymers show low conductivities of magnitude 10−14 S cm−1. Differential scanning calori‐metry measurements reveal that TDPA–aldehyde polymers exhibit glass transitions in the range 170–230 °C. These polymers possess good solubility and the films show sufficient morphological stability.© 2001 Society of Chemical Industry
New interpenetrating polymer networks based on uralkyd–poly(butyl methacrylate)
Authors: Athawale Vilas , Raut Sachin 
Published: January 2005

AbstractA study on two‐component semi‐ and full‐interpenetrating polymer networks (IPNs) of soyabean‐oil based uralkyd resin (UA) and poly(butyl methacrylate) (PBMA) synthesized by a sequential technique, has been conducted. The IPNs obtained are characterized with respect to their mechanical properties, such as tensile strength, percentage elongation and hardness (Shore A). Phase morphology has been studied by scanning electron microscopy. Glass transition studies have been carried out using differential scanning calorimetry. The thermal characterization of the IPNs was undertaken with the aid of thermogravimetric analysis. The apparent densities of these samples have been determined and are compared. The effect of the compositional variation on the above‐mentioned properties was examined. The tensile strength exhibits a sudden rise (approximately three‐fold) for the semi‐ and full‐IPNs with composition UA: PBMA 40% : 60% compared with the UA:PBMA composition of 20% : 40%.© 2001 Society of Chemical Industry
Ultrasonically initiated emulsion polymerization of n‐butyl acrylate
Authors: Wang Qi , Xia Hesheng , Liao Yongqin , Xu Xi , Baxter Steven M , Slone Robert V , Wu Shuguang , Swift Graham , Westmoreland David G 
Published: January 2005

AbstractUltrasonically initiated emulsion polymerization of n‐butyl acrylate (BA) without added initiator has been studied. The experimental results show that high conversion of BA can be reached in a short time by employing an ultrasonic irradiation technique with a high purge rate of N2. The viscosity average molecular weight of poly(n‐butyl acrylate) (PBA) obtained reaches 5.24 × 106 g mol−1. The ultrasonically initiated emulsion polymerization is dynamic and complicated, with polymerization of monomer and degradation of polymer occurring simultaneously. An increase in ultrasound intensity leads to an increase in polymerization rate in the range of cavitation threshold and cavitation peak values. Lower monomer concentration favours enhancement of the polymerization rate. 1H NMR, 13C NMR and FTIR spectroscopies reveal that there are some branches and slight crosslinking, and also carboxyl groups in PBA. Ultrasonically initiated emulsion polymerization offers a new route for the preparation of nanosized latex particles; the particle size of PBA prepared is around 50–200 nm as measured by transmission electron microscopy.© 2001 Society of Chemical Industry
Synthesis and dissociation of amine‐blocked diisocyanates and polyurethane prepolymers
Authors: Gnanarajan T Philip , Iyer N Padmanabha , Nasar A Sultan , Radhakrishnan Ganga 
Published: January 2005

AbstractSubstituted N‐methylanilines are shown to act as blocking agents for toluenediisocyanate. N‐methylaniline‐, N‐methyl‐p‐anisidine‐ and N‐methyl‐p‐nitroaniline‐blocked toluene diisocyanates have been prepared and characterized by FTIR, 1H NMR and 13C NMR spectroscopies, and nitrogen content analysis. A new method for determining the minimum deblocking temperature of the blocked isocyanate is described. The method has advantages in that it can be used to find the minimum deblocking temperature of even non‐volatile blocking agents. The minimum deblocking temperature of the adducts is found to be in the following order: N‐methyl‐p‐anisidine–TDI adduct < N‐methyaniline–TDI adduct < N‐methyl‐p‐nitroaniline–TDI adduct. The anilines exhibit the same trend when they block a polyurethane prepolymer prepared using polypropylene glycol of molecular weight 2000 g mol−1 and tolylene‐2,6‐diisocyanate. The deblocking temperatures are lower in the case of blocked prepolymers than in the blocked adducts. The blocked adducts and prepolymers are reacted with pyromellitic dianhydride (PMDA) in dimethylpropylene urea (DMPU) and the evolution of carbon dioxide is monitored to study the completion of imidization. The reaction time is in accordance with the deblocking ability of the adducts. The regeneration of the blocking agent is confirmed by gas chromatography.© 2002 Society of Chemical Industry
Stress–optical behaviour of polyester networks
Authors: Riande Evaristo , Guzmán Julio 
Published: January 2005

AbstractThermoelastic networks were prepared by end‐linking hydroxyl terminated chains of poly(neopentylglycol hexafluoroglutarate) (PNGHFG) and poly(diethylene glycol terephthalate) (PDET) using, respectively, tri(p‐isocyanate‐phenyl)‐thiophosphate and 2,4‐bis(p‐isocyanate benzyl)‐p‐phenylisocyanate as crosslinking agents. The plots of birefringence versus stress for PNGHFG and PDET networks exhibit negative deviations from linearity at elongation ratios greater than 1.9 and 5, respectively. The values of the optical configuration parameter Δa for the former and latter networks are 2.98 Å3 at 5 °C and 20.80 Å3 at 30 °C, respectively. Theoretical calculations carried out using the conformational energies obtained from the critical analysis of the mean‐square dipole moments of diethyl hexafluoroglutarate and poly(neopentylglycol hexafluoroglutarate) give the value of 2.24 Å3 at 5 °C for this parameter, in fair agreement with the experimental result. Similar calculations carried out on PDET networks give Δa  = 3.74 Å3 at 30 °C, a value significantly lower than the experimental result. The cause of the strong discrepancy between the theoretical and experimental results observed for the optical configuration parameter of PDET is discussed.© 2002 Society of Chemical Industry
Effect of axial stretching on electrical resistivity of short carbon fibre and carbon black filled conductive rubber composites
Authors: Das N C , Chaki T K , Khastgir D 
Published: January 2005

AbstractThe variation of electrical resistivity of carbon black and short carbon fibre (SCF) filled rubber composites was studied against the degree of strain at constant strain rate. It was found that both the degree of strain and strain rate affect the electrical resistivity of the composites. The change in resistivity against the strain and strain rate depends both on the concentration and the type of conductive filler. The incorporation of short carbon fibres (SCF) imparts higher conductivity to the composite than carbon black at the same level of loading. Composites filled with carbon black exhibit better mechanical properties than SCF filled composites. Electrical setting, ie a permanent change in electrical resistivity, was observed during extension–retraction cycles. A good correlation was found between the mechanical response and the electrical response towards strain sensitivity. The results of different experiments are discussed in the light of breakdown and formation of conductive networks in the filled rubber composites.© 2002 Society of Chemical Industry
Copolymerization of butadiene with styrene using a rare‐earth metal compound – dialkylmagnesium – halohydrocarbon catalytic system
Authors: Zhang Qisheng , Ni Xufeng , Shen Zhiquan 
Published: January 2005

AbstractCopolymerizations of butadiene (Bd) with styrene (St) were carried out with catalytic systems composed of a rare‐earth compound, Mg(n‐Bu)2 (di‐n‐butyl magnesium) and halohydrocarbon. Of all the rare earth catalysts examined, Nd(P507)3–Mg(n‐Bu)2–CHCl3 showed a high activity in the copolymerization under certain conditions: [Bd] = [St] = 1.8 mol l−1, [Nd] = 6.0 × 10−3 mol l−1, Mg/Nd = 10, Cl/Nd = 10 (molar ratio), ageing for 2 h, copolymerization at 50 °C for 6–20 h. The copolymer of butadiene and styrene obtained has a relatively high styrene content (10–30 mol%), cis‐1,4 content in butadiene unit (85–90%), and molecular weight ([η] = 0.8–1 dL g−1). Monomer reactivity ratios were estimated to be rBd = 36 and rSt = 0.36 in the copolymerization.© 2002 Society of Chemical Industry