bluuebunny/crossref_metadata_2025 huggingface dataset:
Correlation of ultrasound findings and biochemical markers in the second trimester of pregnancy in fetuses with trisomy 21
Authors: Souter Vivienne L. , Nyberg David A. , El‐Bastawissi Amira , Zebelman Arthur , Luthhardt Fred , Luthy David A.
Published: January 2005

Objective

The aim of the present study was to assess possible correlations between ultrasound findings and maternal serum biochemical (‘triple test’) markers among fetuses with trisomy 21 in the second trimester of pregnancy.

Methods

The study was a retrospective cohort study of 72 pregnancies affected by trisomy 21 who had a second trimester ultrasound and biochemical screen performed at a single center between 1990 and 1999. The biochemical screen consisted of alpha‐fetoprotein (AFP), total beta human chorionic gonadotrophin (hCG) and estriol (uE3). Marker levels were expressed in multiples of the median (MoM). The ultrasound findings assessed were major structural anomalies, short humerus length, short femur length, increased nuchal fold thickness (NF), hyperechoic bowel, echogenic intracardiac focus (EIF), ventriculomegaly, choroid plexus cysts and renal pyelectasis.

Results

Second trimester maternal serum biochemical markers and ultrasound findings appeared to be largely independent of each other. However, some significant correlations were observed. Estriol was significantly lower when a fetal cystic hygroma was detected on ultrasound compared to those with no cystic hygroma (0.40 vs 0.70 MoM, p<0.05). The median hCG level was significantly lower in those pregnancies with a normal second trimester fetal ultrasound compared to those with positive ultrasound findings (2.07 vs 2.87 MoM, p<0.05). Median hCG levels were also significantly higher in those cases with NF⩾5 mm as compared to those with NF<5 mm (2.99 vs 2.49 MoM, p<0.05). This difference persisted after exclusion of the five cases with cystic hygromas (2.99 vs 2.49 MoM, p<0.05). A significant positive correlation was observed between log10 hCG and log10 NF MoM (Spearman's ρ=0.252, p<0.05).

NF was significantly greater among fetuses with an identifiable cardiac defect compared with those without a detectable cardiac defect (median of 7.0 mm vs 3.8 mm, p<0.01). This difference persisted when expressed as multiples of the median (2.8 vs 1.3 MoM, p<0.01).

Conclusion

Second trimester ultrasound and biochemical markers are largely independent in fetuses with trisomy 21, however significant correlations between the two were observed in the present series. These may be important in screening protocols that combine second trimester ultrasound and biochemical markers. Copyright © 2002 John Wiley & Sons, Ltd.
The importance of investigating for uniparental disomy in prenatally identified balanced acrocentric rearrangements
Authors: McGowan Kathryn D. , Weiser Joseph J. , Horwitz Juli , Ann Berend Sue , McCaskill Christopher , Reid Sutton V. , Shaffer Lisa G.
Published: January 2005

We report the finding of paternal isodisomy for chromosome 14 in a fetus found to have a der(14;14)(q10;q10) by amniocentesis. The pregnancy was complicated by severe polyhydramnios and elevated amniotic fluid alpha‐fetoprotein (AFP). The infant showed features consistent with paternal uniparental disomy (UPD) including postnatal growth retardation, poor respiratory function, feeding difficulties, and evidence of hypertrophic cardiomyopathy. The present case, in addition to other reported cases of UPD involving balanced acrocentric rearrangements, supports testing for UPD in prenatally detected Robertsonian translocations and isochromosomes. Copyright © 2002 John Wiley & Sons, Ltd.
Maternal serum human chorionic gonadotrophin and pregnancy‐associated plasma protein A in twin pregnancies in the first trimester
Authors: Niemimaa Marko , Suonpää Mikko , Heinonen Seppo , Seppälä Maija , Bloigu Risto , Ryynänen Markku
Published: January 2005

Objectives

To determine the levels of free β‐human chorionic gonadotrophin (β‐hCG) and pregnancy‐associated plasma protein A (PAPP‐A) in twin pregnancies in the first trimester.

Methods

Serum samples were obtained from 67 pregnant women with twin pregnancies and maternal serum free β‐hCG and PAPP‐A concentrations were compared with those of 4279 singleton controls between the 8th and 13th weeks of gestation.

Results

The geometric means of chromosomally normal twin pregnancies were 1.85 MoM for free β‐hCG and 2.36 MoM for PAPP‐A. There were no cases affected by Down syndrome in either group.

Conclusion

Twin pregnancies secrete more PAPP‐A than expected on the basis of singleton controls whereas free β‐hCG production is not increased. The results of the present study can be used to establish normal reference values when introducing first trimester Down syndrome screening in prenatal care. Copyright © 2002 John Wiley & Sons, Ltd.
Transcervical chorionic villus sampling in multiple pregnancies using a biopsy forceps
Authors: Casals Gemma , Borrell Antoni , Martínez Josep M. , Soler Anna , Cararach Vicenç , Fortuny Albert
Published: January 2005

Objective

The aim of this study was to assess the effectiveness and safety of chorionic villus sampling (CVS) performed in multiple pregnancies by means of a transcervical biopsy forceps.

Methods

The study included CVS performed from January 1990 to March 2000 in our Unit. The results were analysed in two consecutive periods, period A (1990–1994) and period B (1995–2000), in an attempt to assess the effect of increasing experience.

Results

Seventy‐five samplings were performed in 39 multiple pregnancies, 38 twin sets and one triplet. A cytogenetic report was obtained in 73% of cases in period A and in 98% in period B. An abnormal karyotype was observed in 11 samples. The need for subsequent amniocentesis decreased from 38% in period A to 10% in period B. The spontaneous fetal loss rate in chromosomally and structurally normal fetuses before the 20th week decreased from 8.7% in period A to 3.3% in period B. The fetal loss rate after the 20th week was 3.3% in period B and none in period A. It must be noted that in three out of the four cases of fetal loss an amniocentesis was needed after CVS.

Conclusion

Our results suggest that effectiveness and safety improved with increasing experience. Transcervical chorionic villus sampling allows an earlier prenatal genetic diagnosis in multiple pregnancies and this may be particularly relevant for a safer selective termination when chosen by parents if one of the fetuses has an abnormal karyotype. Copyright © 2002 John Wiley & Sons, Ltd.
The population risk of fractures attributable to oral corticosteroids
Authors: Donnan Peter T. , Libby Gillian , Boyter Anne C. , Thompson Philip
Published: January 2005

Purpose

Previous 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.

Methods

The 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.

Results

Approximately 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.

Conclusions

The 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

Purpose

There 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.

Methods

We 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.

Results

We 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.

Conclusions

Recent 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

Assigning 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.
Nonverbal assessment of the Big Five personality factors
Authors: Paunonen Sampo V. , Ashton Michael C. , Jackson Douglas N.
Published: January 2005

The Nonverbal Personality Questionnaire (NPQ) is an experimental, structured, nonverbal measure of 16 personality traits. Its items lack verbal content and, therefore, the inventory is useful for cross‐cultural research. Our goal is this research was to select a subset of the NPQ items to form a new nonverbal questionnaire based on the Five‐Factor Model of personality. We describe the construction of the Five‐Factor Nonverbal Personality Questionnaire (FF‐NPQ), and present data on its psychometric properties. These data include scale internal consistencies, intercorrelations, convergences with verbal measures of the Big Five factors, discriminant validity correlations, correlations with peer ratings, and ability to predict socially important behaviour criteria such as smoking and alcohol consumption. In a second study, we report on the psychometric properties of the FF‐NPQ in an independent sample of respondents from seven different countries. The utility of the new nonverbal inventory for cross‐cultural research is discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Examination of the paths between personality, current mood, its evaluation, and emotion regulation
Authors: Kokkonen Marja , Pulkkinen Lea
Published: January 2005

In an ongoing longitudinal study, a Big Five Personality Inventory was completed by 122 men and 126 women at age 33. At age 36, the Brief Mood Introspection Scale, the Meta‐Evaluation Scale, and the Meta‐Regulation Scale were administered to 140 men and 127 women. The results, based on path analyses, lent support to a hypothesized model, according to which current mood (Negative, Positive, Active, Calm) and mood evaluation (Mood Influence, Typicality and Acceptance, Clarity) mediate the relationship between the Big Five personality traits and emotion regulation strategies (Repair, Dampening, Maintenance). For both sexes, Neuroticism was the most significant trait in terms of emotion regulation. A sex difference emerged: in general, personality traits and mood variables explained emotion regulation more significantly in men. Copyright © 2001 John Wiley & Sons, Ltd.
Test anxiety, evaluative stress, and susceptibility to distraction from threat
Authors: Keogh Edmund , French Christopher C.
Published: January 2005

Examinations are perhaps one of the main methods of assessment in education. Unfortunately, there are some individuals who are so fearful of such events that performance is impaired. Test anxiety is believed to be the trait that predisposes individuals to react negatively to examinations and tests. One way in which it is believed that test anxiety affects performance is by increasing susceptibility to distraction from task‐irrelevant material. However, few studies have directly investigated this impairment. An experiment was therefore conducted to investigate susceptibility to distraction in high and low test‐anxious students. The task used was based on one developed by Mathews, May, Mogg and Eysenck (1990), which distinguishes between focused attention and selective search. In order to determine whether a specific susceptibility to distraction exists, the distractors were varied in terms of valence and relevance to examinations. Since test anxiety is a situation‐specific trait, an evaluation‐related stressor was used to trigger test‐anxious reactions. A specific susceptibility to distraction from threat was found amongst high test‐anxious participants who received the evaluation‐related stressor. However, this effect was only found when participants were using focused attention. This suggests that the disturbed performance often found to be associated with test anxiety might be due to an inability to ignore threatening material when attempting to focus attentional resources. These results are discussed in light of current theories of test anxiety and implications for educational practice. Copyright © 2001 John Wiley & Sons, Ltd.
The concept and status of trait in research on temperament
Authors: Strelau Jan
Published: January 2005

The aim of the paper is to show that research on temperament is inescapably bound with the concept of trait as applied in personality research. It is the individual differences approach on which temperament studies are based, and traits are the basic units by means of which these differences are described. Taking as a point of departure the definition of trait understood as a relatively stable and individual‐specific generalized tendency to behave or react in a certain way expressed in a variety of situations, the hypothetical status of temperament traits is discussed. Special attention is paid to states and behaviour by means of which temperament traits are inferred as well as to the biological and environmental determinants of these traits. Temperamental traits constitute only a part of the personality structure viewed from the perspective of individual differences and this perspective is only one of the many from which the complex nature of personality should be viewed. Copyright © 2001 John Wiley & Sons, Ltd.
Procrastination as self‐regulation failure of performance: effects of cognitive load, self‐awareness, and time limits on ‘working best under pressure’
Authors: Ferrari Joseph R.
Published: January 2005

Effects of cognitive load, objective self‐awareness and time limits on the self‐regulation of performance speed and accuracy were investigated between procrastinators and non‐procrastinators. In experiment 1 chronic procrastinators completed fewer items (slow speed) and made more errors (less accuracy) than non‐procrastinators under high but not low cognitive load conditions when the time span was limited and brief. In experiment 2 chronic procrastinators performed slower than non‐procrastinators under a 2 second, but not under no limit, 1 second, or 4 second time limit conditions. Chronic procrastinators compared to non‐procrastinators also performed more slowly and made more performance errors under objective self‐awareness conditions regardless of the length of time. These experiments indicate that chronic procrastinators regulate ineffectively their performance speed and accuracy when they ‘work under pressure’ (defined by high cognitive load, objective self‐awareness, and imposed time limitations). Copyright © 2001 John Wiley & Sons, Ltd.
Analysis of genetic influences on the consistency and variability of the Big Five across different stressful situations
Authors: Lensvelt‐Mulders Gerty , Hettema Joop
Published: January 2005

Several studies have demonstrated that individual differences in personality traits, known as the Big Five, have a genetic component. These personality traits are considered important predictors of everyday behaviour. In addition to personality traits there are also factors in the environment that govern behaviour. This dual influence on behaviour is statistically reflected in a P × S interaction. This study examines the genetic and environmental influences on the interactions between a person and his daily life environment for the Big Five. Fifty‐seven identical twin pairs and 43 fraternal twin pairs participated in this study. Trait related behaviour was measured in 30 different situations with the aid of an SR inventory. The heritability coefficients for the main effect of P were in the normal range, varying between 0.35 for Agreeableness and 0.53 for Conscientiousness. The heritability coefficients for the P × S interactions were moderately high, explaining between 26% and 69% of the total P × S variance. The consequences of these results for general and behavioural genetic research on the Big Five will be discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Individual differences and social norms: the distinction between reciprocators and prosocials
Authors: Perugini Marco , Gallucci Marcello
Published: January 2005

Reciprocity is in this contribution compared with cooperation, hostility, and prosociality, in order to distinguish its peculiar theoretical and empirical characteristics. Two studies are presented. Study 1 (n = 166) is based on the distinction between the mechanism of reciprocity and the consequent behaviour that this mechanism produces. It is shown that participants have a clear implicit theory of the personality traits underlying reciprocal behaviour, and these traits are well differentiated with respect to traits underlying cooperation and hostility. Study 2 (n = 134) is based on the distinction between reciprocity as a goal and reciprocity as a strategy to achieve equality. Results show that individuals with high internalization of the norm of reciprocity allocate payoffs as a function of the valence of other's past behaviour, whereas this feature is irrelevant for individuals with high prosocial orientation. Copyright © 2001 John Wiley & Sons, Ltd.
Replicable types and subtypes of personality: Spanish NEO‐PI samples
Authors: Boehm Bettina , Asendorpf Jens B. , Avia Maria D.
Published: January 2005

Three major personality prototypes were derived on the basis of a Big Five instrument (NEO‐PI) by means of replicated cluster analysis in two Spanish samples (a sample from the general population and a student sample). The replicability of the three prototypes within and their consistency between the two samples were evaluated. In addition, subtypes were analysed in a similar way. Finally, the relation between prototype assignment and level of education was examined in the sample from the general population. Within‐study replicability was satisfactory only for the student sample. Comparison with the results for a similar instrument (NEO‐PI‐R) applied to a German sample showed satisfactory consistency only for the student sample. Discussion centres on the strong sample dependency of the results. 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

The 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

Free‐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

Sensitive 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

4‐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

Polystyrene‐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

Two 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

Compounds 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

Synthesis 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

New 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

A 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

Ultrasonically 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

Substituted 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

Thermoelastic 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

The 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

Copolymerizations 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
Rheological behaviour of suspensions prepared from plate‐shaped titanium dioxide particles in (hydroxypropyl) methylcellulose aqueous solution
Authors: Maeyama Kaoru , Yamaguchi Hiroshi , Mukouhara Tomohiro , Kawaguchi Masami , Kato Tadaya
Published: January 2005

Suspensions were prepared by homogeneously mixing titanium dioxide particles in (hydroxypropyl) methylcellulose (HPMC) aqueous solutions. Thin plate‐shaped particles were made from balloon materials crushed to pieces. The other three types of particles used as references were plate‐shaped samples surface‐modified with alumina, and two types of spherical particles of anatase and rutile forms. Plateau adsorption amounts of HPMC onto particles depended on their surface properties. Comparisons of rheological behaviour were carried out among the residual three samples except for the sample having the rutile form. Within the concentration range used, the viscosity values of suspensions were rather lower than that of HPMC aqueous solutions. The reason for such low values was attributed to the decrease of entanglements in the semi‐dilute regime and also to steric stabilization resulting from the formation of the HPMC adsorbed layer. The change of structural viscosity and its recovery were evaluated by observation of the decrease of viscosity and its recovery as an indicator. It was confirmed that suspensions of thin plate‐shaped particles had superior structural recovery performance.

© 2002 Society of Chemical Industry
Synthesis and photopolymerization of hyperbranched polyurethane acrylates applied to UV curable flame retardant coatings
Authors: Zhu Sheng‐Wu , Shi Wen‐Fang
Published: January 2005

A series of hyperbranched polyurethane acrylates containing phosphorus were prepared by reaction of a phosphorus‐containing triol with toluene‐2,4‐diisocyanate and hydroxylethyl acrylate at given ratios. The resins obtained were found to polymerize rapidly in the presence of a photofragmenting initiator under UV irradiation, and the maximum polymerization rate increased with temperature up to 125 °C, then decreased quickly. The UV cured films have flame retardancy with a limiting oxygen index of 27.0.

© 2002 Society of Chemical Industry
Synthesis of novel polyurethanes containing dioxybenzylidenecyanoacetate, as non‐linear optical chromophores and their properties
Authors: Lee Ju‐Yeon , Park Eun‐Ju
Published: January 2005

Methyl 3,4‐di‐(2′‐hydroxyethoxy)benzylidenecyanoacetate (3) was prepared by hydrolysis of methyl 3,4‐di‐(2′‐vinyloxyethoxy)benzylidenecyanoacetate (2). Diol 3 was condensed with 2,4‐toluenediisocyanate, 3,3′‐dimethoxy‐4,4′‐biphenylenediisocyanate, and 1,6‐hexamethylenediisocyanate to yield polyurethanes 4, 5 and 6 containing the non‐linear optical (NLO) chromophore 3,4‐dioxybenzylidenecyanoacetate. The resulting polyurethanes 4–6 were soluble in common organic solvents such as acetone and DMF. Tg values of the polymers obtained from DSC thermograms were in the range 80–102 °C. Polymers 4–6 showed thermal stability up to 300 °C in TGA thermograms, and electro‐optic coefficients (r33) of the poled polymer films were in the range 10–12 pm V−1 at 633 nm, which are acceptable for NLO device applications.

© 2002 Society of Chemical Industry
Effect of pH on gelatin self‐association investigated by laser light scattering and atomic force microscopy
Authors: Lin Wei , Yan Lifeng , Mu Changdao , Li Wan , Zhang Mingrang , Zhu Qingshi
Published: January 2005

The effect of pH on gelatin self‐association in dilute solution has been investigated for the first time to the authors' knowledge by laser light scattering (LLS) and atomic force microscopy (AFM). It shows that, at the isoelectric point (IEP) of gelatin, the ampholyte macromolecules collapse due to electrostatic attraction forces of oppositely charged groups, and self‐association occurs in turn by an intermolecular association process. The soluble aggregates are stabilized by ionic contacts, hydrogen bonds and hydrophobic interactions, and are protected from precipitation by hydrophilic groups on the surface of the particles. For gelatin‐B away from the IEP, pH ≥ 6.0 or pH ≤ 4.0, the molecular chains behave more like random coils. As expected, the association–disassociation based mainly on electrostatic interactions appears reversible to some certain extent. The experimental results indicate that LLS and AFM, especially a combination of the two, play an important role in obtaining integrated and direct information on the structure and properties of this natural biopolymer.

© 2002 Society of Chemical Industry
ZnS as fire retardant in plasticised PVC
Authors: Schartel Bernhard , Kunze Ralf , Neubert Dietmar , Tidjani Adams
Published: January 2005

The flame retardant effect of zinc sulphide (ZnS) in plasticised poly(vinyl chloride) (PVC‐P) materials was investigated. PVC‐P containing different combinations of additives such as 5% ZnS, 5% of antimony oxide (Sb2O3) and 5% of mixtures based on Sb2O3 and ZnS were compared. The thermal degradation and the combustion behaviour were studied using thermogravimetry (TG), coupled with FTIR (TG–FTIR) or with mass spectroscopy (TG–MS), and a cone calorimeter, respectively. A detailed and unambiguous understanding of the decomposition and release of the pyrolysis products was obtained using both TG–MS and TG–FTIR. The influence of ZnS, Sb2O3 and the corresponding mixtures on the thermal decomposition of PVC‐P was demonstrated. Synergism was observed for the combination of the two additives. The combustion behaviour (time to ignition, heat release, smoke production, mass loss, CO production) was monitored versus external heat fluxes between 30 and 75 kW m−2 with the cone calorimeter. Adding 5% of ZnS has no significant influence on the fire behaviour of PVC‐P materials beyond a dilution effect, whereas Sb2O3 works as an effective fire retardant. Synergism of ZnS and Sb2O3 allows the possibility of replacing half of Sb2O3 by ZnS to reach equivalent fire retardancy.

© 2002 Society of Chemical Industry
Crystallization behaviour of poly(butylene succinate) copolymers
Authors: Park Jun Wuk , Kim Dong Kook , Im Seung Soon
Published: January 2005

Poly(butylene succinate‐co‐butylene 2‐methyl succinate) (PBSMS) random copolymers were synthesized with various comonomer compositions and their crystallization behaviour and morphology were investigated by differential scanning calorimeter, small angle X‐ray scattering and polarized optical microscopy. The equilibrium melting temperature obtained by the Hoffman–Weeks plot significantly decreased with increasing comonomer concentration containing methyl side‐groups. Spherulitic growth rates were strongly dependent on comonomer concentration and were analyzed using the Lauritzen–Hoffman kinetic theory. The surface free energy (σσe) dramatically decreased with comonomer contents. From analysis of the SAXS data, the dependence of the lamellar thickness on crystallization temperature decreased with increasing comonomer concentration.

© 2002 Society of Chemical Industry
Effects of trans‐polyoctylene rubber on rheological and green tensile properties of natural rubber/acrylonitrile–butadiene rubber blends
Authors: Nah Changwoon
Published: January 2005

The influence of trans‐polyoctylene rubber (TOR) on the flow property, die swell behaviour and green tensile property of NR (natural rubber)/NBR (acrylonitrile–butadiene rubber) blend compound was investigated as a function of TOR loading level. The pure TOR, NR and NBR compounds were also investigated for comparison with the blend compounds. The shear viscosity of TOR strongly depended on the temperature as well as shear rate. The viscosity of the NR/NBR blend compound was even lower than that of the constituent components at relatively lower shear rates, and the viscosity difference became smaller as the shear rate was increased. The viscosity of the NR/NBR blend compounds was strongly affected by the addition of TOR but the effect became negligible with increasing the shear rate. Both the die‐swell ratio and the surface topology of extrudates were also affected by TOR addition; the dependence on shear rate was much stronger for higher TOR level. The NR/NBR blend compound showed much higher green tensile strength and elongation at break than those of the constituent components. Both the green tensile modulus and strength of the NR/NBR blend compound were greatly enhanced, while the elongation at break was reduced with the addition of TOR.

© 2002 Society of Chemical Industry