bluuebunny/crossref_metadata_2025 huggingface dataset:
Split notochord syndrome — prenatal ultrasonographic diagnosis
Authors: Almog B. , Leibovitch L. , Achiron R.
Published: August 2002

Split notochord syndrome is a rare condition that is characterized by a persistent connection of the gut and dorsal skin of the back, an enteric cyst and vertebral anomalies. We present two cases in which prenatal ultrasound showed polyhydramnios. In one case it was associated with vertebral abnormalities and a right‐sided mediastinal cyst found to be the stomach. Postnatal evaluation confirmed the diagnosis of split notochord syndrome. The association of sonographic findings of hydramnios, thoracic cysts and vertebral anomalies suggests prenatal diagnosis of split notochord syndrome. Copyright © 2001 John Wiley & Sons, Ltd.
The effect of a systemic arteriovenous fistula on the pulmonary arterial blood pressure in the fetal sheep
Authors: Jouannic J.‐M. , Martinovic J. , Roussin R. , Laborde F. , Dumez Y. , Dinh‐Xuan A. T.
Published: August 2002

In order to investigate whether systemic arteriovenous fistula occurring during the fetal period could induce pulmonary hypertension at birth, a fistula was surgically created between the carotid artery and jugular vein of fetal lambs at 120 days' gestation. Mean pressures in the left pulmonary artery, aorta, atrium and ventricles were measured at birth in seven experimental animals and in five control animals. Mean left pulmonary pressure was significantly higher in the lambs with fistula as compared with the control group, suggesting that prenatal occurrence of systemic arteriovenous fistula may induce fetal pulmonary hypertension. The present study provides a new animal model that could be relevant for the study of mechanisms regulating pulmonary vascular tone in the perinatal period. Copyright © 2002 John Wiley & Sons, Ltd.
Can we predict 22q11 status of fetuses with tetralogy of Fallot?
Authors: Boudjemline Younes , Fermont Laurent , Le Bidois Jérôme , Villain Elizabeth , Sidi Daniel , Bonnet Damien
Published: August 2002

Objective

To determine if chromosome 22q11 deletion status can be predicted in fetuses with tetralogy of Fallot as regards additional phenotypic anomalies.

Methods

One hundred and fifty‐one consecutive fetuses with tetralogy of Fallot without or with pulmonary atresia were screened for 22q11 deletion. Additional echographic features [increased nuchal translucency (NT), intrauterine growth retardation (IUGR), polyhydramnios, extracardiac malformations, pulmonary arteries abnormalities] were noted.

Results

Twenty‐five fetuses had a 22q11 deletion (16.6%). Increased NT, polyhydramnios and IUGR were more frequent in fetuses with 22q11 deletion as well as pulmonary arterial abnormalities. When these different features were present in the same fetus with tetralogy of Fallot, 22q11 deletion can be predicted with a sensitivity of 88%.

Conclusion

Simple echographic features can help to predict 22q11 status in fetuses with tetralogy of Fallot. This may improve the efficiency of prenatal screening for this defect. Copyright © 2002 John Wiley & Sons, Ltd.
Prenatal diagnosis in two families with autosomal, p47phox‐deficient chronic granulomatous disease due to a novel point mutation in NCF1
Authors: de Boer Martin , Singh Vinita , Dekker Jan , Di Rocco Maja , Goldblatt David , Roos Dirk
Published: August 2002

Objective

Prenatal diagnosis was required in two unrelated families with chronic granulomatous disease (CGD) patients who lacked expression of p47phox protein; thus a search for mutations in NCF1 was undertaken.

Methods

Gene scanning was applied to establish the relative number of coding and pseudo‐NCF1 genes. PCRs specific for coding NCF1 cDNA and coding NCF1 exon‐7 genomic DNA were devised.

Results

The normal 1:2 ratio of coding and pseudo‐NCF1 genes was found in the patients. Sequencing of the RT‐PCR product specific for mRNA from the coding NCF1 genes revealed a novel homozygous G579A mutation in both patients, changing the TGG codon for Trp193 into the TAG stop codon. This mutation was confirmed in genomic DNA. The parents of both patients were found to be heterozygotes for this mutation. In the chorionic villus DNA of the first family a heterozygous G579A mutation was found. Postpartum, functional NADPH oxidase tests were normal. In the second family, this mutation was present in homozygous form in the chorionic villus DNA. Following termination of the pregnancy, the diagnosis of p47phox‐deficient CGD was confirmed on DNA extracted from fetal blood.

Conclusion

This is the first report of prenatal diagnosis in p47phox‐deficient CGD. Copyright © 2002 John Wiley & Sons, Ltd.
Single umbilical artery stenosis associated with intrauterine fetal death post‐transfusion
Authors: Meir Karen , Yagel Simcha , Amsalem Hagai , Ariel Ilana
Published: August 2002

Single umbilical artery is among the most common funicular vascular anomalies. In contrast, umbilical artery stenosis is rare, and has only been reported in three‐vessel cords. We describe a case of single umbilical artery stenosis in a fetus with no associated malformations. Intrauterine fetal death occurred at 28weeks' gestation following cordocentesis and intravascular transfusion for Rhesus alloimmunization. Single umbilical artery stenosis may place the fetus at increased risk, particularly in cases requiring interventions involving cord manipulation. Copyright © 2002 John Wiley & Sons, Ltd.
Does a ‘notched’ nuchal translucency indicate Down syndrome fetuses or other adverse pregnancy outcome?
Authors: Maymon Ron , Dreazen Eli , Buckovsky Ian , Weinraub Zwi , Herman Arie
Published: August 2002

The aim of the present study was to assess the sonographic contour of the increased nuchal translucency (NT) and to correlate this with pregnancy outcome. Fifty sonographic images of fetuses with increased NT [>95th centile thickness of the normal range for crown–rump length (CRL) between 38 and 84 mm] were retrospectively assessed. In all the cases a complete pregnancy and even infancy follow‐up (<36 months) was available. The NT appearances were subdivided into two forms: a ‘notched’ or ‘uniform’ appearance. The images were correlated with karyotype results [trisomy 21 (DS) vs euploid cases] and pregnancy outcome. Complicated outcomes were classified as being either DS fetuses, miscarriage or termination of pregnancy because of structural anomaly. Thus 30/35 (86%) of the euploid fetuses had a ‘uniformly’ increased NT, whereas 8/13 DS cases (62%) had a ‘notched’ appearance (Fisher's exact test, p=0.004). Additionally, 27/29 fetuses (93%) which had an uneventful pregnancy outcome had a ‘uniform’ increased NT, whereas 12/26 (57%) of the fetuses which had adverse pregnancy outcome had a ‘notched’ appearance of their NT (Fisher's exact test, p<0.001). Although it was not possible to correlate the sonographic data with post‐evacuation microdissection findings, it is possible that a uniformly shaped, increased NT may be more representative of a developmental delay in a normal fetus. Conversely, a ‘notched’ nuchal surface may represent abnormal lymphatic or cardiovascular development more commonly seen in DS fetuses. Copyright © 2001 John Wiley & Sons, Ltd.
Minimized analysis of costs applied to antimicrobial consumption in a rural area
Authors: Sánchez Cristina Corres , Nájera Lorena Hermosilla , Inchaurregui Luis Carlos Abecia
Published: August 2002

Purpose

Antimicrobial agents constitute one of the most utilized groups of drugs in daily clinical practice and, therefore they involve a significant expense. The aim of this study was to evaluate the economic cost of the antimicrobials prescribed in a rural area as well as to search for some cheaper alternatives.

Methods

Retrospective study. The economic cost of antimicrobial agents prescribed at a health centre over 18 months was studied. To do this, clinical histories of 800 people were reviewed. Afterwards, a minimized analysis of costs was carried out.

Results

The total cost of antimicrobial consumption came to 2 080 752 pts. The average expenditure per patient came to 6433.85 ± 14 269.29 pts. Significant differences between the sexes were not found; however, the expenditure in patients of 65 years of age or over was significantly higher than the rest. After applying the ABC analysis it was noticed that macrolides, cephalosporins, antimicrobial combinations and quinolones were the most important groups from an economic point of view. The use of monodose containers would allow us to save up to 7.83% of the total expenditure. In addition, by prescribing the cheapest marketed pharmaceutical product we could save a further 6.54%, and, finally, by combining these two measures the total possible saving would reach 299 052 pts, a 14. 37% of the total expenditure.

Conclusion

We consider important the elaboration of pharmacoeconomic guides as well as the introduction of monodose containers not only at hospitals but also at community pharmacists. Copyright © 2001 John Wiley & Sons, Ltd.
Advances in identifying women at risk of breast cancer and in treating the disease
Authors: Howell Anthony
Published: August 2002

Epidemiological studies have identified risk factors for breast cancer. The majority of these are related to estrogen exposure, such as early menarche, late menopause, and use of oral contraceptives and hormone replacement therapy. More recently, part of the reason for familial breast cancer has been explained. In families with multiple breast and/or ovarian cancers there is likely to be mutations in the cell‐cycle control/DNA repair genes BRCA‐1, BRCA‐2 and p53. It is now routine in major centres to test for mutations. When found, preventive measures such as prophylactic mastectomy can be discussed with women. About 5–10% of breast cancer is caused by gene mutation. We do not know the initiating factors in the remainder but we know that a large proportion are related to estrogen, which increases proliferation of normal breast epithelial cells, thus increasing the chances of carcinogenesis, and also promotes proliferation of the altered cell afterwards.

The importance of estrogen has been translated into therapy, first by ovarian ablation and in recent years by antiestrogens and, in post menopausal women, the aromatase inhibitors, which lower serum estrogen concentrations. Antiestrogens (e.g., tamoxifen) were shown to be effective for the treatment of advanced breast cancer over thirty years ago. This led to their use after surgery. When given for five years, deaths are reduced by 10–20%. Together with early diagnosis and mammographic screening it is likely that tamoxifen has contributed to the 30% reduction in breast cancer deaths in the UK. Now tamoxifen is used to prevent breast cancer in women at risk. An American study (NSABP P1) of 14 000 women showed that those randomized to tamoxifen had 50% fewer invasive and in‐situ cancers compared with controls given placebo. If this result is replicated in the UK trial (IBIS I), tamoxifen may be more widely used for women at risk. Similar reductions in breast cancer risk were seen in a study using the antiestrogen raloxifene, which has the advantage of not causing endometrial stimulation. Tumours which arise in women given preventative antiestrogens are mostly estrogen receptor negative. In the future we need to find how to prevent these and also to evaluate the preventative effects of lifestyle changes, such as weight loss and increased physical activity. Copyright © 2001 John Wiley & Sons, Ltd.
Drug use investigation (DUI) and prescription‐event monitoring in Japan (J‐PEM)
Authors: Tanaka Katsutoshi , Morita Yasuko , Kawabe Eri , Kubota Kiyoshi
Published: August 2002

Objective

To present ethical issues and relevant problems in observational studies of drug safety in Japan.

Methods

The Pharmaceutical Affairs Law, associated ordinances, and notifications relevant to Drug Use Investigations (DUIs), and published documents for two pilot studies of prescription‐event monitoring in Japan (J‐PEM) were examined, particularly with regard to the protection of privacy. Information relevant to the proposed legislation intended to protect personal information and proposed guidelines on ethical issues in epidemiological studies were also collected.

Results and Conclusion

The formal studies inaugurated as the ‘side‐effect investigations’ in the late 1960s and replaced by those of the DUI in 1980 have been conducted by drug manufacturers, in accordance with the Pharmaceutical Affairs Law. The first pilot study of J‐PEM was started in 1997 and the second one is currently operated under a Health Sciences Research grant, supported by the Ministry of Health and Welfare. Those observational studies have been conducted while maintaining the confidentiality of personal data, but without requiring either approval by institutional ethics boards or informed consent from patients. However, according to the Pharmaceutical Affairs Law, those involved in postmarketing surveillance studies must protect the privacy of study subjects and those who break this rule may be subject to penalties. Ethical issues associated with pharmacoepidemiological studies will be clearly determined in Japan before the end of 2001 when the law designed to protect personal information will be introduced and official guidelines on ethical issues in epidemiological studies will have come into effect. Copyright © 2001 John Wiley & Sons, Ltd.
Radical polymerization of styrene by a hexa‐substituted‐ethane type thermal iniferter
Authors: Qin Shu‐Hui , Qiu Kun‐Yuan , Swift Graham , Wu Shuguang , Westmoreland David G
Published: August 2002

The bulk polymerization of styrene (St) initiated with a hexa‐substituted‐ethane type initiator, diethyl 2,3‐dicyano‐2,3‐diphenylsuccinate (DCDPS), was investigated. It was found that DCDPS served as a thermal iniferter for polymerization of St and the polymerization had some characteristics in common with living radical polymerization, ie, both the yield and the molecular weight of the resulting polymers increased with increasing reaction time. The resultant polystyrene can act as a macroinitiator for chain‐extension polymerization of St or for radical polymerization of methyl methacrylate to give a block copolymer.

© 2001 Society of Chemical Industry
Study of kinetics and mechanisms of dispersion polymerization of 2‐hydroxypropyl methacrylate
Authors: Wang Yan‐Jun , Liu Jin‐Mei , Yuan Cai‐Deng , Liu Jiang‐Feng , Tan Xin , Cao Tong‐Yu
Published: August 2002

In the present work, the dispersion polymerization of 2‐hydroxypropyl methacrylate (HPMA) was carried out in No. 120 gasoline/n‐pentanol medium using azobisisobutyronitrile as initiator and a comb‐structured amphipathic polymer as dispersant. The effects of many factors such as the type, structure and concentration of dispersants, and the reaction temperature, on the reaction and the morphology of the polymer microspheres obtained were investigated. It is proposed that the dispersion polymerization of HPMA has two nucleation mechanisms, homogeneous nucleation and inverse mini‐emulsion nucleation. Furthermore, the kinetic of HPMA dispersion polymerization was also studied.

© 2001 Society of Chemical Industry
Synthesis and characterization of poly(urethane‐co‐imidine)s having pendent phenyl and benzylidene groups using bisphthalides, bislactones and blocked polyurethane prepolymers
Authors: Iyer N Padmanabha , Nasar A Sultan , Gnanarajan T Philip , Radhakrishnan Ganga
Published: August 2002

Poly(urethane‐co‐imidine)s were prepared using amine blocked polyurethane (PU) prepolymer. The PU prepolymer was prepared by the reaction of poly(propylene glycol) (PPG2000) and 2,4‐tolylene diisocyanate (TDI) and end capped with N‐methyl aniline. The PU prepolymer was then reacted with bisphthalides and bislactones, until the evolution of carbon dioxide ceased. Polymerization reactions with bispthalides and bislactone took more time than with dianhydrides. Polymers were characterized by FTIR, GPC, TG and DSC analyses. Molecular weights of the poly(urethane‐co‐imidine)s were found to be lower than that of poly(urethane‐co‐imide)s. Compared to poly(urethane‐co‐imide)s all poly(urethane‐co‐imidine)s showed high glass transition temperature and crystallization peak in DSC. The thermal stability of the polyurethanes was found to increase with the introduction of imidine component.

© 2001 Society of Chemical Industry
Synthesis and characterization of a random terpolymer of L‐lactide, ϵ‐caprolactone and glycolide
Authors: Srisa‐ard Mangkorn , Molloy Robert , Molloy Nipapan , Siripitayananon Jintana , Sriyai Montira
Published: August 2002

A random terpolymer of L‐lactide (LL), ϵ‐caprolactone (CL) and glycolide (G) has been synthesized in bulk at 130 °C using stannous octoate as the coordination–insertion initiator. The terpolymer, poly(LL‐ran‐CL‐ran‐G), has been characterized by a combination of analytical techniques: GPC, 1H NMR, 13C NMR, DSC and TG. Molecular weight characterization by GPC shows a unimodal molecular weight distribution with values of
M
n = 1.01 × 105 g mol−1 and
M
w /
M
n = 2.17. Compositional and microstructural analysis by 1H NMR and 13C NMR, respectively, reveal a terpolymer composition of LL:CL:G = 74:15:11 (mol%) with a chain microstructure consistent with random monomer sequencing. This latter view is supported by the terpolymer temperature transitions (Tg and Tm) from DSC and the thermal decomposition profile from TG. The results and, in particular, the conclusion that it is a random rather than a statistical terpolymer are discussed in the light of current theories regarding the mechanism of this type of polymerization.

© 2001 Society of Chemical Industry
Biodegradable blends of poly(ε‐caprolactone) with α‐chitin and chitosan: specific interactions, thermal properties and crystallization behavior
Authors: Senda Toshihiko , He Yong , Inoue Yoshio
Published: August 2002

Films of poly(ε‐caprolactone) (PCL) blends with α‐chitin and chitosan were prepared as completely biodegradable polyester/polysaccharide composites. DSC thermal analysis revealed that the crystallization of PCL was suppressed by blending with α‐chitin and chitosan. The specific interaction between PCL and polysaccharides was investigated by FTIR spectroscopy. The PCL carbonyl vibration bands could be resolved into three components: crystalline, amorphous and interacting. The FTIR spectra indicated that there were hydrogen bonding interactions between PCL and polysaccharides, and that polysaccharides suppressed the crystallization of PCL, consistent with the results obtained by DSC.

© 2001 Society of Chemical Industry
The effect of benzenesulfonamide plasticizers on the glass transition temperature of an amorphous aliphatic polyamide
Authors: Groote Ph De , Devaux J , Godard P
Published: August 2002

The plasticizing effect of benzenesulfonamides (BSAs) on an amorphous aliphatic polyamide (AAPA) has been studied using dynamic mechanical analysis of copper‐supported spin‐coated mixtures. It follows that N‐(n‐butyl)BSA (BBSA), an amorphous liquid hydrogen bonding BSA, is fully miscible with AAPA because their mixtures are characterized by a single glass transition (Tg) throughout the compositional range. The Tg–composition dependence, however, is not linear because experimental results suggest a 20 K fall in Tg occurring around 0.65 BBSA units per amide unit, which coincides with the system shifting from a polymer‐like to a liquid‐like glass‐forming material. When considering a crystallizable hydrogen‐bonding plasticizer such as ethylBSA (EBSA), AAPA/EBSA mixtures become fully crystalline at a 1.3 EBSA unit per amide group. Nevertheless, melting point depression together with the single Tg observed throughout the compositional range on quenched (and therefore amorphous) samples confirms the miscibility of AAPA chains with the plasticizer. N,N‐DialkylBSAs, which lack the sulfonamide proton and therefore the possibility of hydrogen bonding with amide groups, quickly phase separate from AAPA, the glass transition of the latter staying mainly unaffected apart from a small (9 K) decrease at 10–15 mol% plasticizer.

© 2001 Society of Chemical Industry
Thermal and mechanical properties of diglycidylether of bisphenol A/ trimethylolpropane triglycidylether epoxy blends cured with benzylpyrazinium salts
Authors: Park Soo‐Jin , Kim Taek‐Jin , Kim Hak‐Yong
Published: August 2002

The effect of blend composition on thermal stability and mechanical properties of diglycidylether of bisphenol A (DGEBA)/trimethylolpropane triglycidylether (TMP) epoxy blends cured with benzylpyrazinium salts (N‐benzylpyrazinium hexafluoroantimonate, BPH) as a thermal latent catalyst was investigated. The thermal stability, characterized by the initial decomposition temperature, temperature of maximum rate of weight loss, integral procedural decomposition temperature, and activation energy for decomposition, increase in DGEBA‐rich compositions. This could be due to the long repeat unit and stable aromatic ring in the DGEBA. The mechanical properties are also discussed in terms of the fracture toughness (KIC), flexural and impact tests for the blend composition studied. The addition of TMP into DGEBA gives systematic improvements in fracture toughness, which results from the increase in aliphatic and flexible chain segments of TMP.

© 2002 Society of Chemical Industry
Psychometric data for teacher judgments regarding the learning behaviors of primary grade children
Authors: Crosby Edward G. , French Joseph L.
Published: August 2002

The psychometric properties of the Classroom Performance Profile (CPP), a teacher rating scale, were investigated using primary grade children from economically at‐risk families. Students were rated as they progressed from kindergarten through third grade. The CPP demonstrated high internal consistency yielding Cronbach alpha coefficients for the total score of at least .96. CPP ratings were correlated with scores from the Woodcock‐Johnson Psycho‐Educational Battery–Revised: Tests of Achievement and the Social Skills Rating System–Teacher Form, Elementary Level. Results suggest that the CPP ratings were positively correlated with measures of academic achievement, academic competence, and social skills, and negatively correlated with problem behaviors. © 2002 Wiley Periodicals, Inc.
Best practices in the identification of gifted students with learning disabilities
Authors: McCoach D. Betsy , Kehle Thomas J. , Bray Melissa A. , Siegle Del
Published: August 2002

In recent years, researchers and practitioners have become increasingly interested in students who have both learning disabilities and intellectual gifts. Intellectually gifted students are defined as those who demonstrate outstanding ability to grapple with complexity, or superior academic potential. The definition of learning disability states that the level of performance in a particular academic area is substantially below what would be expected based on one's general intellectual ability and that this incongruity cannot be explained by lack of educational opportunity in that academic area. This article explores several controversial issues surrounding the identification of students as both gifted and learning disabled. How does a discrepancy manifest itself in a student who is intellectually gifted? Do gifted students with learning disabilities experience masking effects? How can we effectively identify intellectually gifted students with learning disabilities? In addition, we argue against the use of profile analysis to identify gifted students with learning disabilities. Finally, we propose guidelines for school psychologists to identify students with intellectual gifts and learning disabilities, and we provide suggestions for how to best serve this unique population of students within the school environment. © 2001 John Wiley & Sons, Inc.
Effects of pure non‐ionic and mixed non‐ionic–cationic surfactants on the rates of hydrolysis of phenyl salicylate and phenyl benzoate in alkaline medium
Authors: Khan M. Niyaz , Ismail Emran , Yusoff M. Rapandy
Published: August 2002

The pseudo‐first‐order rate constants (kobs) for the alkaline hydrolysis of phenyl benzoate (PB) decrease monotonically from 72.0 × 10−4 to 7.4 × 10−4 s−1 with increase in the concentration of polyoxyethylene 23 lauryl ether ([C12E23]T) from 0.0 to 0.01 M at 0.01 M NaOH and 35 °C. The results fit satisfactorily to a pseudophase model of micelles. The values of kobs for the hydrolysis of ionized phenyl salicylate (PS−) are almost independent of [C12E23]T within the range 0.0–0.02 M at 0.01 and 0.03 M NaOH and 35 °C. The rate of alkaline hydrolysis of PB appears to be negligible in the micellar pseudophase than in the aqueous pseudophase, which is ascribed to the extremely low concentration of HO− in the micellar region of micellized PB molecules. The values of kobs for hydrolysis of PB and PS− at 0.01 M NaOH become almost zero at ≥0.02 and ≥0.03 M C12E23, respectively. The effects of mixed C12E23–CTABr on kobs for the alkaline hydrolysis of PB reveal that mixed micelles behave like pure CTABr micelles within the [C12E23]T range 0.0–5 × 10−4 M whereas an increase in [C12E23]T from ≥7 × 10−4 to 0.02 M decreases kobs at 0.006, 0.01, 0.02 and 0.03 M CTABr. However, the values of kobs are significantly higher at [CTABr]T = 0.006, 0.01, 0.02 and 0.03 M than at [CTABr]T = 0 in the presence of [C12E23]T in the range >5 × 10−4 –0.02 M. An increase in [C12E23]T from 0.0 to 0.015 M causes nearly a twofold increase in kobs at 0.01, 0.02 and 0.03 M CTABr and 0.01 M NaOH. Copyright © 2001 John Wiley & Sons, Ltd.
Mechanistic studies of the oxidation of substituted phenethyl alcohols by N‐metallo‐N‐haloarylsulphonamides: kinetic isotope studies
Authors: Rangappa Kanchugarakoppal S.
Published: August 2002

The oxidation of para‐substituted phenethyl alcohols (PEA, 2) by N‐metallo‐N‐haloarylsulphonamides (1) in the presence of dilute HCl to the corresponding phenacetaldehydes (4) is first order with respect to oxidant (1) and [H+] and a fractional order each in [PEA] and [Cl−]. Addition of the reaction product (3), ionic strength variations and variation of dielectric constant of the medium had no effect on the rate. The oxidation of PhCH2CD2OH (2) exhibited a substantial primary kinetic isotope effect (kH/kD = 5.83). The rates correlate satisfactorily with the Hammett free energy relationship. The activation parameters ΔH≠, ΔS≠, ΔG≠ and logA were calculated for the reaction. The proposed mechanism is consistent with the observed results. Copyright © 2001 John Wiley & Sons, Ltd.
In situ atom transfer radical polymerization of styrene with a tetraethylthiuram disulfide/copper bromide/2,2′‐bipyridine initiating system
Authors: Li Peng , Qiu Kun‐Yuan
Published: August 2002

The living radical polymerization of styrene in bulk was successfully performed with a tetraethylthiuram disulfide/copper bromide/2,2′‐bipyridine (bpy) initiating system. The initiator Et2NCS2Br and the catalyst cuprous bromide (CuBr) were produced from the reactants in the system through in situ atom transfer radical polymerization (ATRP). A plot of natural logarithm of the ratio of original monomer concentration to monomer concentration at present, ln([M]0/[M]) versus time gave a straight line, indicating that the kinetics was first‐order. The number‐average molecular weight from gel permeation chromatography (GPC) of obtained polystyrenes did not agree well with the calculated number‐average molecular weight but did correspond to a 0.5 initiator efficiency. The polydispersity index (i.e., the weight‐average molecular weight divided by the number‐average molecular weight) of obtained polymers was as low as 1.30. The resulting polystyrene with α‐diethyldithiocarbamate and ω‐Br end groups could initiate methyl methacrylate polymerization in the presence of CuBr/bpy or cuprous chloride/bpy complex catalyst through a conventional ATRP process. The block polymer was characterized with GPC, 1H NMR, and differential scanning calorimetry. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4001–4008, 2001
Microstructure of glycidylmethacrylate/vinyl acetate copolymers by two‐dimensional nuclear magnetic resonance spectroscopy
Authors: Brar A. S. , Yadav Anil
Published: August 2002

Glycidylmethacrylate/vinyl acetate copolymers were prepared by solution polymerization with benzene as a solvent and benzoyl peroxide as an initiator. Copolymer compositions were determined from 1H NMR spectra, and comonomer reactivity ratios were determined by the Kelen–Tudos (KT) method and the nonlinear least‐squares error‐in‐variable method (EVM). The reactivity ratios obtained from KT and EVM were rG = 37.4 ± 12.0 and rV = 0.036 ± 0.019 and rG = 35.2 and rV = 0.03, respectively. Complete spectral assignments of 13C and 1H NMR spectra were done with the help of distortionless enhancement by polarization transfer and two‐dimensional 13C–1H heteronuclear single quantum coherence and total correlation spectroscopy. The methyl, methine, and methylene carbon resonance showed both stereochemical and compositional sensitivity. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4051–4060, 2001
Photoswitchable architectural polymer: Toward azo‐based polyamidoamine side‐chain dendritic polyester
Authors: Ghosh Samaresh , Banthia Ajit K.
Published: August 2002

A versatile approach to the synthesis of novel polyamidoamine (PAMAM) side‐chain dendritic polyester (SCDPE) possessing azobenzene motifs in the polymeric core is described and displayed reversible cis–trans (E/Z) isomerization upon exposure to UV light. A polymerization reaction was conducted in solution using ester‐terminated PAMAM dendritic diol (1a, G 3.5) and azobenzene dicarboxylic acid chloride in the presence of triethylamine. PAMAM dendritic diol 1a as well as SCDPE (1) were thoroughly characterized by means of IR and NMR (1H and 13C) spectroscopies. The intrinsic viscosity of 1 at 36 °C in CHCl3 was found to be 0.38 dl/g. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4182–4188, 2001
Polyimides based on 2,5‐bis(4‐aminophenoxy)biphenyl
Authors: Yang Chin‐Ping , Chen Ruei‐Shin
Published: August 2002

A diamine monomer II, 2,5‐bis(4‐aminophenoxy)biphenyl, was prepared through a nucleophilic substitution reaction of phenylhydroquinone and p‐chloronitrobenzene in the presence of potassium carbonate in N,N‐dimethylformamide, followed by catalytic reduction with hydrazine and Pd/C. A series of all‐aromatic, organosoluble polyimides bearing pendent phenyl groups were synthesized from the diamine with six kinds of commercial dianhydrides via a conventional two‐stage process. For improving solubility of polypyromellitimide, copolypyromellitimides with arbitrary solubilities were prepared from II and a pair of dianhydrides, which were mixed at certain molar ratios. These polymers showed good solubilities in N‐methyl‐2‐pyrrolidone and m‐cresol. The softening temperatures of these polyimides were recorded between 206 and 269 °C. Polymers had glass‐transition temperatures at 230–286 °C and 10% weight‐loss temperatures above 521 °C in air or nitrogen atmospheres. Their films had high tensile moduli and strengths. Excellent properties of these polyimides are attributed to the incorporation of the pendent phenyl group in diamine II. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 429–438, 2002; DOI 10.1002/pola.10116
Benzoyl peroxide‐initiated copolymerization of citronellol and vinyl acetate
Authors: Pandey Prachi , Srivastava A. K.
Published: August 2002

The radical copolymerization of citronellol with vinyl acetate (VA) in xylene at 60 ± 0.1 °C for 90 min in the presence of benzoyl peroxide follows ideal kinetics and results in the formation of an alternating copolymer as demonstrated by the values of the reactivity ratios [r1 (VA) = 0.02 and r2 (citronellol) = 0.0002], which have been calculated with the Kelen–Tüdos method. The overall activation energy is computed to be 75 kJ/mol. The IR spectrum of the copolymer shows the presence of bands at 3400 cm−1 due to an alcoholic group and 1750 cm−1 due to a 〉CO group. The values of the Mark–Houwink constants for this copolymer system have been determined with gel permeation chromatography to be α = 0.375 and K = 2.4 × 10−4. The glass‐transition temperature, determined with differential scanning calorimetry, is 68.32 °C. The mechanism has been elucidated. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1243–1252, 2002
Formation of polymeric micelles with amino surfaces from amphiphilic AB‐type diblock copolymers composed of poly(glycolic acid lysine) segments and polylactide segments
Authors: Ouchi Tatsuro , Miyazaki Hidetake , Arimura Hidetoshi , Tasaka Fumitaka , Hamada Atsushi , Ohya Yuichi
Published: August 2002

Amphiphilic AB‐type diblock copolymers composed of hydrophobic poly(L‐lactide) (PLA) segments and hydrophilic poly(glycolic acid lysine) [poly(Glc‐Lys)] segments with amino side‐chain groups self‐associated to form PLA‐based polymeric micelles with amino surfaces in an aqueous solution. The average diameter of the loose core–shell polymeric micelles for poly(Glc‐Lys) [number‐average molecular weight (Mn) = 1240]‐b‐PLA (Mn = 7000) obtained by a dimethyl sulfoxide/water dialysis method was estimated to be about 50 nm in water by dynamic light scattering measurements. The size and shape of the obtained polymeric micelles were further observed with transmission electron microscopy and atomic force microscopy. To investigate the possibility of applying the obtained PLA‐based polymeric micelles as bioabsorbable vehicles for hydrophobic drugs, we tested the entrapment of drugs in poly(Glc‐Lys) (Mn = 1240)‐b‐PLA (Mn = 7000) micelles and their release with doxorubicin as a hydrophobic drug. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1426–1432, 2002
Highly isotactic polymethacrylates through radical polymerization of methacrylate esters of some ortho‐bridged triaryl carbinols
Authors: Hatziyiannakou Athina , Froussios Cleanthis
Published: August 2002

The polymerization of 9‐phenyl‐10,10‐dioxo‐thioxanthen‐9‐yl and 9‐phenyl‐10‐oxo‐9,10‐dihydroanthracen‐9‐yl methacrylates obtained under radical initiation (α,α‐azobisisobutyronitrile) in benzene solution proceeds with high isotactic specificity to afford homopolymers with a triad mm content higher than 95%, having presumably a helical main‐chain structure and showing significant resistance to solvolytic degradation in methanol. 9‐Phenyl‐10,10‐dipropyl‐9,10‐dihydroanthracen‐9‐yl methacrylate similarly affords isotactic polymers with an mm of 98% but is much less durable in contact with methanol. The high isotacticity observed for the aforementioned polymethacrylates as well as for poly(1‐phenyl‐dibenzosuberyl methacrylate), previously reported in the literature, reveal a tendency of ortho‐bridged triarylcarbinols to enforce isotacticity on their methacrylate polymers obtained under radical initiation. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1180–1186, 2001
Melt‐processable poly(oxyphenylalkanoate): Synthesis, properties, and in vitro degradation of poly(4‐oxyphenylacetate)
Authors: Prasad V. S. , Pillai C. K. S. , Kricheldorf H. R.
Published: August 2002

The homopolyester of 4‐hydroxyphenylacetic acid (HPAA) was synthesized by one‐pot, slurry‐melt, and acidolysis melt polymerization techniques and was characterized by its inherent viscosity and IR and NMR spectra. Differential scanning calorimetry (DSC), polarizing light microscopy (PLM), and wide‐angle X‐ray diffraction (WAXD) studies of the homopolymer were carried out for its thermal and phase behavior. The results indicated that the yield and molecular weight of the polymer depended on the method of preparation; moreover, the acidolysis melt polymerization of the pure acetoxy derivative of HPAA was the best method for the preparation of high molecular weight poly(4‐oxyphenylacetate) (polyHPAA) without side reactions. DSC and PLM studies also showed that the thermal and optical properties depended largely on the polymerization conditions and inherent viscosity values. PolyHPAA did not show a clear texture typical of liquid‐crystalline polymers, whereas after cooling from the melt, structures similar to spherulitic crystals were observed. WAXD patterns showed a crystalline nature. The in vitro degradability of the polymer was also studied via the water absorption in buffer solutions of pH 7 and 10 at 30 and 60 °C; this was followed by Fourier transform infrared, inherent viscosity, DSC, thermogravimetric analysis, WAXD, and scanning electron microscopy techniques. Unlike Vectra®, which showed no degradation, polyHPAA showed an increase in hydrolytic degradation from 5.0 and 6.0% at 30 °C to 12.5 and 15.0% at 60 °C after 350 h in buffer solutions of pH 7 and 10, respectively. The results indicated a possible biomedical prosthetic application of poly(oxyphenylalkanoate)s such as polyHPAA with better crystallinity coupled with degradability as a substitute for poly(hydroxyalkanoates). © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2430–2443, 2001
Synthesis and properties of a novel, liquid, trifunctional, cycloaliphatic epoxide
Authors: Xie Meiran , Wang Zhonggang , Zhao Yunfeng
Published: August 2002

A novel cycloaliphatic triepoxide, 1,1‐bis(2′,3′‐epoxycyclohexyloxymethyl)‐3,4‐epoxycyclohexane (II), and its precursor, 1,1‐bis(2′‐cyclohexenyloxymethyl)‐3‐cyclohexene, were synthesized. Their chemical structures were confirmed with IR spectroscopy, elemental analysis, and 1H NMR spectroscopy. II was easily cured with hexahydro‐4‐methylphthalic anhydride with 1,3,5‐triethylhexahydro‐s‐triazine as a curing accelerator. The physical properties of the cured product were examined with thermomechanical analysis, thermogravimetric analysis, and dynamic mechanical analysis. Compared with the commercial diepoxide ERL‐4221 under the same curing conditions, the cured product based on II showed a much higher glass‐transition temperature (198 °C), a higher crosslinking density (2.08 × 10−3 mol/cm3), and a lower coefficient of thermal expansion [6.2 × 105(/°C)]. II may become a promising candidate material for modern microelectronic packaging. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2799–2804, 2001
Synthesis and characterization of novel polyimide from bis‐(3‐aminophenyl)‐4‐(trifluoromethyl)phenyl phosphine oxide
Authors: Jeong Kwang Un , Jo Young‐Jun , Yoon Tae‐Ho
Published: August 2002

A novel diamine, bis‐(3‐aminophenyl)‐4‐(trifluoromethyl)phenyl phosphine oxide (mDA3FPPO), containing phosphine oxide and fluorine moieties was prepared via the Grignard reaction from an intermediate, 4‐(trifluoromethyl)phenyl diphenyl phosphine oxide, that was synthesized from diphenylphosphinic chloride and 4‐(trifluoromethyl)bromobenzene, followed by nitration and reduction. The monomer was characterized by Fourier transform infrared (FTIR), 1H NMR, 31P NMR, 19F NMR spectroscopies; elemental analysis; melting point measurements; and titration and was used to prepare polyimides with a number of dianhydrides such as pyromellitic dianhydride (PMDA), 5,5′‐[2,2,2‐trifluoro‐1‐(trifluoromethyl)ethyliden]‐bis‐1,3‐isobenzofuranedione (6FDA), 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA), and 4,4′‐oxydiphthalic dianhydride (ODPA). Polyimides were synthesized via a conventional two‐step route; preparation of polyamic acids, followed by solution imidization, and the molecular weight were controlled to 20,000 g/mol. Resulting polyimides were characterized by FTIR, NMR, DSC, and intrinsic viscosity measurements. Refractive‐index, dielectric constant, and adhesive properties were also determined. The properties of polyimides were compared with those of polyimides prepared from 1,1‐bis‐(4‐aminophenyl)‐1‐phenyl‐2,2,2‐trifluoroethane (3FDAm) and bis‐(3‐aminophenyl) phenyl phosphine oxide (mDAPPO). The polyimides prepared from mDA3FPPO provided high glass‐transition temperatures (248–311 °C), good thermal stability, excellent solubility, low birefringence (0.0030–0.0036), low dielectric constants (2.9–3.1), and excellent adhesive properties with Cu foils (107 g/mm). © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3335–3347, 2001
Reverse atom transfer radical polymerization of vinyl monomers with Fe[SC(S)NEt2]3 alone as the catalyst
Authors: Qin Dong‐Qi , Qin Shu‐Hui , Qiu Kun‐Yuan
Published: August 2002

The living radical polymerization of methyl methacrylate and styrene was successfully carried out with diethyl 2,3‐dicyano‐2,3‐diphenylsuccinate (DCDPS)/ferric tri(diethyldithiocarbamate) as a novel reverse atom transfer radical polymerization initiation system in which DCDPS was a hexa‐substituted ethane‐type thermal iniferter, DC was a diethyldithiocarbamate group, and no additional ligands such as nitrogen‐ or phosphine‐based compounds were required. The bulk polymerization of methyl methacrylate was carried out at 95 °C, and that of styrene was carried out at 120 °C. Poly(methyl methacrylate) and polystyrene (PSt) with high molecular weights and quite narrow molecular weight distributions (as low as 1.09 for PSt) were obtained. 1H NMR spectroscopy revealed the presence of an α‐(carbethoxycyanophenyl)methyl group from the initiator and an ω‐DC group from the catalyst in the obtained polymers. Various chain‐extension reactions under UV light or thermal treatments were successfully conducted to prove the presence and efficient reinitiating of the ω‐DC group. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3464–3473, 2001
Persistent spectral hole‐burning study on dendrimer porphyrins
Authors: Machida Shinjiro , Sugihara Koichi , Takahashi Isoko , Horie Kazuyuki , Jiang Dong‐Lin , Aida Takuzo
Published: August 2002

We report the first results of persistent spectral hole burning of dendrimer porphyrins having three‐, four‐, or five‐layered aryl ether dendritic arrays. We evaluate structural relaxations of dendrimer framework around the porphyrin core at low temperatures. A large environmental change around the porphyrin core, as evaluated from the hole area, was suppressed in dendrimer porphyrins of higher generation numbers, whereas a small environmental change, as evaluated from hole width, showed no dependence on the number of generations. The dendrimer porphyrins showed sharp holes at 20 K, suggesting a long dephasing time and the suppression of spontaneous spectral diffusion. The results of dendrimer‐embedded polymer sample indicated that the structural relaxation of polymer chain outside the dendrimer does not have an influence on the resonant frequency of the porphyrin core. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 210–215, 2002
Approach for the calculation of high‐order connectivity indices of polymers and its application
Authors: Zhong Chongli , Yang Chunsheng
Published: August 2002

A method for the calculation of connectivity indices of polymers was developed that can be used to calculate any order connectivity indices of polymers in a consistent and unambiguous manner without any truncation errors. The proposed method makes it possible to correlate the physical properties of polymers in terms of connectivity indices of higher than first order, which may not only improve the correlation and prediction accuracy but also possibly eliminate the normally required atomic and group correction terms to develop more general correlations with reliable predictive capability. As an example, two correlations with connectivity indices up to the third order are proposed to correlate the thermal conductivities at room temperature for 20 amorphous polymers. The two proposed correlations give comparable or even better accuracy than the existing one, which requires connectivity indices up to the first order and an atomic correction term. Because only connectivity indices were used in the newly proposed correlations, they are general models with better predictive capability. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 401–407, 2002; DOI 10.1002/polb.10104
Effect of compression on the solid polymer electrolytes: The modified lattice‐fluid model
Authors: Young Ahn Woo , Bae Young Chan
Published: August 2002

A molecular thermodynamic model based on the theory of melting point depression, the Adam–Gibbs configurational entropy model, and the modified lattice‐fluid model was developed to interpret ionic conductivities of solid polymer electrolytes with various pressures. A new configurational entropy, S was introduced in this model. Quantitative descriptions according to the proposed model agreed with the experimental data for the given systems. Our results showed that a eutectic point moves toward higher melting temperatures, whereas a lower weight fraction of salt and the ionic conductivity significantly decrease with pressure. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 706–713, 2002
Lactone ring formation in poly(α‐hydroxyacrylic acid)
Authors: Yamazawa Kazuyoshi , Kawauchi Susumu , Satoh Mitsuru
Published: August 2002

Lactone ring formation in poly(α‐hydroxyacrylic acid) (PHA) was investigated by means of 1H and 13C NMR. The stereoregularity of PHA was estimated as syndio‐rich (ca. 86%) on the basis of methylene proton peak of the sodium salt, PHANa, in aqueous solution. On the other hand, analyses of the 13C NMR spectra obtained as a function of the degree of dissocation (α) suggested that the lactone ring is formed at every other residue at half dissociation (α = 0.5). This specific way of lactone formation supposed for PHA is discussed in relation to the critical change in the dissociation behavior of the polyacid which has been found at α = 0.5. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1400–1405, 2002
Molecular dynamics study of the stereostructure of 1,4‐linked poly(cyclohexa‐1,3‐diene) obtained with π‐allylnickel‐based catalysts
Authors: Tanimura Shinobu , Matsuoka Takaaki , Nakano Mitsuru , Usuki Arimitsu
Published: August 2002

Temperature‐constant and pressure‐constant molecular dynamics simulations of crystalline 1,4‐linked poly(cyclohexa‐1,3‐diene) (CHD) were performed using the COMPASS force field. Powder X‐ray diffraction spectra calculated from the simulated atomic coordinates were compared with the measured spectrum of the crystal of 1,4‐linked poly(CHD), obtained using a bis(allylnickel bromide) (ANiBr)/methylaluminoxane (MAO) catalyst. As a result of the comparison, the geometrical isomerism of the 1,4‐linked poly(CHD) obtained with the ANiBr/MAO catalyst was found to be cis syndiotactic. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 973–978, 2001
Induced changes of polymer organization in a gel of poly(vinyl alcohol) crosslinked by Congo red
Authors: Atkin N. J. , Abeysekera R. M. , Chenery D. H. , Robards A. W.
Published: August 2002

Different gel microstructures are induced at variable poly(vinyl alcohol) (PVA) and Congo red concentrations, as revealed by ultrarapid freezing and a replica technique for transmission electron microscopy. The polymer microstructures observed include random coils, rigid polymer rods, and long fibers. The development of the different polymer conformations is proposed to be dependent on the degree of intramolecular and intermolecular crosslinking and on the electrostatic interactions of the Congo red ions. The rigid‐rod conformation appears to be the most energetically stable form; it is disrupted by electrostatic effects around the polymer overlap concentration (C*PVA). We propose that the gel microstructure influences the physical properties of the gel. Gels possessing the rigid‐rod microstructure have increased Young's storage modulus values. Two possible mechanisms of gelation are suggested. The first describes a one‐stage reaction when the polymer concentration approximates C*PVA, where polymers in an extended random‐coil conformation undergo intermolecular crosslinking without any microstructural changes. The second describes a two‐stage reaction when the polymer concentration is less than or greater than C*, where a disorder–order transition results in the formation of rigid polymer rods and fibers followed by the formation of a macromolecular network. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1471–1483, 2001