bluuebunny/crossref_metadata_2025 huggingface dataset:
The tough economy prompts companies to shift their approach to sales compensation
Authors: Dorf Paul R. , Masur Lisette F.
Published: February 2004

When the economy nose‐dived after the boom of the 1990s, some companies modified their sales
compensation plans as a way to reduce costs—in some cases with undesirable results. More progressive
companies modified their sales strategies first and then reshaped compensation to align sales force behavior
with the new business realities. The authors examine four case studies and offer recommendations on how to
reconcile the desire for cost containment with the need to focus the sales force on those customers, products,
and services that can produce profits in even a tight economy. © 2004 Wiley Periodicals,
Inc.
Leadership style and values chart the course for an entrepreneurial journey
Authors: Whalen Matthew , Khin‐Maung‐Gyi Felix , Smithwick David
Published: February 2004

Three leaders of a ten‐year‐old start‐up company reveal how they have used transparent
leadership to create employee commitment, inculcated core values to drive organizational behavior, and made
clear communications a competitive advantage. They also share how customer care, continuous learning, and
intentional community have helped nurture their basement business into a nationally recognized success.
© 2004 Wiley Periodicals, Inc.
Sovereign bank develops a methodology for predicting the ROI of training programs
Authors: Engel Sherry , Kapp Karl M.
Published: February 2004

Taking a page from the finance function's play book, the Learning and Development Team of Sovereign Bank
crafted a return on investment methodology that predicts the hard‐dollar business impact of proposed
training iniatives. Along the way the team also learned to speak the language of business. © 2004
Wiley Periodicals, Inc.
Ritz‐Carlton and EMC: The gold standards in operational behavioral differentiation
Authors: Bacon Terry R. , Pugh David G.
Published: February 2004

The authors tell the stories of Ritz‐Carlton Hotels and EMC Corporation, two companies whose
customer‐centric behaviors differentiate them from their competitors and have produced extraordinary
levels of business performance and customer satisfaction and loyalty. © 2003 Terry R. Bacon and
David G. Pugh
Prenatal diagnosis of enteric duplication cyst of the tongue
Authors: Rousseau Thierry , Couvreur Stéphanie , Senet‐Lacombe Eve , Durand Christine , Justrabo Eve , Malka Gabriel , Sagot Paul
Published: February 2004

Cysts located on the tongue are rare and usually diagnosed in childhood. Here we report on the prenatal diagnosis of an unusual cystic malformation of the tongue with heterotopic intestinal tissue explored by prenatal ultrasound, magnetic resonance imaging and on its surgical treatment and histological examination. The prenatal differential diagnoses as well as perinatal management of cystic lesions of the tongue are reviewed. Copyright © 2004 John Wiley & Sons, Ltd.
Maternal education modifies the age‐related increase in the birth prevalence of Down syndrome
Authors: Khoshnood Babak , Wall Stephen , Pryde Peter , Lee Kwang‐sun
Published: February 2004

Objective

To test the hypothesis that the age‐related increase in the birth prevalence of Down syndrome is less for women with higher levels of education due to their more frequent use of prenatal diagnosis.

Methods

We compared the effects of maternal age on the odds of Down syndrome at birth, and on amniocentesis use, in women with <12 years of education with those who had ≥12 years of education. We used a national data set and analyzed the effects of education separately for African Americans (N = 1 643 054), and non‐Hispanic whites (N = 6 676 885) in the US birth cohorts of 1989–1991. Analyses included Mantel–Haenszel and logistic regression models with the likelihood ratio test to assess interactions between education and age effects.

Results

For both African Americans and non‐Hispanic whites, the age‐related increase in the odds of Down syndrome was substantially less for women with higher levels of education (p < 0.001). For both ethnic groups, women with higher levels of education were more likely to use amniocentesis (p < 0.001).

Conclusions

Our results suggest that women with higher levels of education are more likely to use prenatal diagnosis. Moreover, this effect of education on prenatal diagnosis use, translates into a lower rate of age‐related increase in the birth prevalence of Down syndrome. Copyright © 2004 John Wiley & Sons, Ltd.
Fetal DNA in maternal plasma as a screening variable for preeclampsia. A preliminary nonparametric analysis of detection rate in low‐risk nonsymptomatic patients
Authors: Farina Antonio , Sekizawa Akihiko , Sugito Yumi , Iwasaki Mariko , Jimbo Masatoshi , Saito Hiroshi , Okai Takashi
Published: February 2004

Objective

Our objective was to examine whether plasma fetal DNA can be used as a screening variable in those women who developed preeclampsia but without any clinical symptom at the time of blood draw.

Methods

Fetal DNA was extracted from 1.5‐mL plasma samples, and the DYS14 gene was analyzed by real‐time quantitative polymerase chain reaction. Plasma collected and frozen from six women were each paired with five matched control samples of identical specimen type from gravid women carrying a presumed normal male fetus. Matched rank‐sum analysis and nonparametric receiver operating characteristic (ROC) curves analysis of estimated multiples of median (MoM) were used for calculating detection rate (DR) and false‐positive rate (FPR).

Results

The mean observed rank of 5.08 in the cases was significantly higher than the expected 3.18 (p‐value = 0.013). Pregnancies that will develop a preeclampsia exhibit 2.39‐fold higher levels of maternal plasma cell‐free fetal DNA compared to matched controls. DR was 33 and 50% at an FPR of 5 and 10% respectively.

Conclusions

The estimated DR allows to consider fetal DNA as a potential variable to predict preeclampsia in a low‐risk population. Further studies will be addressed to calculate a parametric statistical algorithm and to estimate a proper posterior risk of the disease by means of fetal DNA alone or combined with other markers. Copyright © 2004 John Wiley & Sons, Ltd.
Pilot study on the midsecond trimester examination of fetal nasal bone in the Chinese population
Authors: Chen Min , Lee Chin Peng , Leung Kwok Yin , Hui Pui Wah , Tang Mary Hoi Yin
Published: February 2004

Objectives

Hypoplasia of the nasal bone of fetuses affected by trisomy 21 and other aneuploidies could be detected by prenatal ultrasound examination and was an important new marker in the detection of Down syndrome in the second trimester. Racial differences in fetal nasal bone length have been reported. However, there was no reference range for the fetal nasal bone length (NBL) in the Chinese population. We conducted a pilot study to investigate the reproducibility of the measurement of fetal NBL in the mid second trimester and to determine whether there is any difference in NBL between the Chinese and the Caucasian population.

Methods

From June 2002 to February 2003, 198 Chinese women were examined. Ultrasound measurements of NBL were performed on a strictly midsagittal plane in normal singleton fetuses at 15 to 23 weeks' gestation.

Results

The mean difference in the NBL between the two investigators was small (mean = 0.043 mm; 95% CI, −0.033 to 0.12), and there was substantial agreement between the measurements for each observer. Limits of agreement were −0.48 to 0.35 and −0.29 to 0.22 mm in the two investigators respectively. It was found that the median length of the nasal bones increased from 3.5 mm at 15 weeks to 6.7 mm at 23 weeks' gestation. There was a linear relationship between the length of the nasal bone and the gestational age.

Conclusion

It was demonstrated that the measurement of nasal bone length was feasible and reproducible in the second trimester. The fetal nasal bone length in Chinese population appeared shorter than that of Caucasian and African–Americans. There is a need to establish a reference range of fetal NBL for the Chinese population. Copyright © 2004 John Wiley & Sons, Ltd.
Structural chromosomal mosaicism and prenatal diagnosis
Authors: Pipiras E. , Dupont C. , Chantot‐Bastaraud S. , Siffroi J. P. , Bucourt M. , Batallan A. , Largillière C. , Uzan M. , Wolf J. P. , Benzacken B.
Published: February 2004

True structural chromosomal mosaicism are rare events in prenatal cytogenetics practice and may lead to diagnostic and prognostic problems. Here is described the case of a fetus carrying an abnormal chromosome 15 made of a whole chromosome 2p translocated on its short arm in 10% of the cells, in association with a normal cell line. The fetal karyotype was 46,XX,add(15)(p10).ish t(2;15)(p10;q10)(WCP2+)[3]/46,XX[27]. Pregnancy was terminated and fetus examination revealed a growth retardation associated with a dysmorphism including dolichocephaly, hypertelorism, high forehead, low‐set ears with prominent anthelix and a small nose, which were characteristic of partial trisomy 2p. Possible aetiologies for prenatal mosaicism involving a chromosomal structural abnormality are discussed. Copyright © 2004 John Wiley & Sons, Ltd.
Ultrasound screening of fetal structural abnormalities at 12 to 14 weeks in Hong Kong
Authors: Chen Min , Lam Yung Hang , Lee Chin Peng , Tang Mary Hoi Yin
Published: February 2004

Objective

Ultrasound screening for fetal abnormalities is conventionally performed at 18 to 20 weeks of gestation. Recent data suggested that many fetal structural abnormalities could be detected by ultrasound examination at 12 to 14 weeks of pregnancy. In this study, we investigated the effectiveness of early ultrasound examination in the detection of fetal abnormalities in women aged 35 years or older.

Methods

From February 1998 to March 2001, pregnant women aged 35 or above were examined by transabdominal and transvaginal sonography between 12 and 14 weeks of gestation. If the anatomical survey was normal, the women underwent routine 16‐ to 20‐week ultrasound examination. Pregnancy outcome was obtained from the hospital records or by contacting the subjects.

Results

Twenty‐six of the 1609 fetuses had structural abnormalities. Fourteen were detected at the ultrasound examination at 12 to 14 weeks. Detection rate was 53.8% (14/26; 95% CI 44, 64) with a false‐positive rate of 0.3% (5/1583; 95% CI 0.16, 0.44). Six additional abnormalities (23.1%, 6/26) were detected at 16‐ to 20‐week ultrasound examination. The overall detection rate of structural abnormalities was 76.9% (20/26; 95% CI 68.6, 85.2).

Conclusions

The effectiveness of ultrasound examination at 12 to 14 weeks to screen for fetal abnormalities approached that achieved at 20 weeks and can be a good adjunct to the conventional examination. Copyright © 2004 John Wiley & Sons, Ltd.
Reversal of twin–twin transfusion syndrome: frequency, vascular anatomy, associated anomalies and outcome
Authors: Wee Ling Y. , Taylor Myles J. O. , Vanderheyden Tina , Wimalasundera Ruwan , Gardiner Helena M. , Fisk Nicholas M.
Published: February 2004

Objective

To determine the frequency of reversal of transfusional gradient and phenotype in a large cohort of prospectively studied cases of twin–twin transfusion syndrome (TTTS) and seek evidence of clinical or placental anastomotic associations.

Methods

Consecutive cases of TTTS seen over an eight‐year period with serial documentation of ultrasonic growth, liquor volume and fetal and placental Doppler studies were reviewed. Postnatal injection studies were inspected.

Results

Reversal of TTTS occurred in 5 of 96 affected pregnancies (5%). Two of the five cases had underlying aneuploidy or genetic syndrome, higher than the 2% frequency found in cases without reversal of TTTS (p < 0.05). Placental anastomotic configurations provided no consistent explanation for reversal of phenotype.

Conclusion

This study documents the frequency of reversal of the direction of TTTS, and suggests that it is a heterogeneous condition. Reversal of donor–recipient phenotype may be explained by haemodynamic changes secondary to underlying aneuploidy/genetic syndromes, to the presence of multiple anastomoses in either direction or following laser ablation. This series together with previous case reports argues for a high level of suspicion for underlying aneuploidy, genetic syndrome or structural defects where there is reversal of the donor–recipient phenotype. Copyright © 2004 John Wiley & Sons, Ltd.
Prenatal diagnosis of the distal 11q deletion and review of the literature
Authors: Chen Chih‐Ping , Chern Schu‐Rern , Chang Tung‐Yao , Tzen Chin‐Yuan , Lee Chen‐Chi , Chen Wen‐Lin , Chen Li‐Feng , Wang Wayseen
Published: February 2004

Objectives

To present the prenatal diagnosis of de novo distal 11q deletions and a review of the literature.

Clinical Subjects and Methods

A 31‐year‐old primigravid woman underwent amniocentesis at 20 weeks' gestation because of a maternal serum alpha‐fetoprotein (MSAFP) level of 2.63 multiples of the median. Amniocentesis demonstrated a karyotype of 46,XY,del(11)(q24.2). The parental karyotypes were normal. Level II ultrasound revealed short femurs and humeri, and overlapping of the toes. Postnatally, the proband manifested additional findings of the characteristic facial dysmorphism and camptodactyly. A 38‐year‐old gravida 2, para 1, woman underwent amniocentesis at 18 weeks' gestation because of advanced maternal age. Amniocentesis revealed a karyotype of 46,XX,del(11)(q24.1). The parental karyotypes were normal. Level II ultrasound did not show fetal structural abnormalities. Postnatally, the proband manifested characteristic facial dysmorphism and camptodactyly.

Results

Of these two cases, genetic marker analysis determined the paternally derived distal deletions of chromosome 11q and the deletion breakpoints. A comparison of the present cases with the reported cases of prenatally diagnosed distal 11q deletion is made.

Conclusion

The distal 11q deletion can be identified prenatally because of parental balanced translocations involving chromosome 11, previous‐term infants with an unbalanced rearrangement, advanced parental age, sonographically detected fetal abnormalities and abnormal maternal serum screening. Fetuses with de novo distal 11q deletions may be associated with elevated MSAFP and abnormal sonographic findings of the digits and limbs in the second trimester. Copyright © 2004 John Wiley & Sons, Ltd.
Retrospective diagnosis and subsequent prenatal diagnosis of Nijmegen breakage syndrome
Authors: Muschke Petra , Gola Hannswerner , Varon Raymonda , Röpke Albrecht , Zumkeller Walter , Wieacker Peter , Stumm Markus
Published: February 2004

Objective

We report on the retrospective diagnosis of Nijmegen breakage syndrome (NBS) confirmed by molecular genetic analysis and consecutive prenatal diagnosis in the same family.

Method

Thirteen years after the death of their daughter due to fatal recurrent infections, a couple presented in our genetic counselling unit asking for the recurrence risk of their daughter's disease. Retrospective analysis of the medical record suggested that the girl might have suffered from NBS. Therefore, molecular genetic analysis for NBS was performed in the parents.

Results

After the diagnosis, NBS could be indirectly proven by molecular genetic heterozygosity testing of the parents, and a reliable prenatal diagnosis for a new pregnancy could be offered. In a following pregnancy, a massive hydrocephalus was diagnosed by ultrasound investigation. Amniocentesis was performed, and molecular analysis of the fetal DNA revealed homozygosity for the NBS1 mutation 657del5.

Conclusion

The analysis of this family allows a further delineation of the prenatal NBS phenotype including hydrocephalus and dystopic kidneys that are helpful parameters to recognise NBS prenatally, also by ultrasound investigations in pregnancy. Additionally, we conclude that hydrocephalus might be more common in NBS patients than previously suggested. Copyright © 2004 John Wiley & Sons, Ltd.
Integrated first‐ and second‐trimester Down syndrome screening test among unaffected IVF pregnancies
Authors: Maymon Ron , Shulman Adrian
Published: February 2004

Objective

The aim of the current study was to assess the profile of markers that constitute the integrated test and to measure its false‐positive rates (FPR) among a preselected group of unaffected IVF pregnancies. These results were compared with the reference laboratory values that reflect the general obstetric population, which underwent the same investigative protocol.

Methods

Ninety‐nine unaffected singletons from IVF‐pregnant women and 1781 controls, all evaluated by the same laboratory, underwent a nondisclosure integrated Down syndrome screening test. This test comprised first‐trimester nuchal translucency (NT) and pregnancy‐associated plasma protein‐A (PAPP‐A) assessment, followed by a midgestation quadruple test. Only upon completion of the integrated screening test, the parturient women were informed of its results.

Results

The mean maternal age of the study and the control group was 32.2 ± 4 and 30.4 ± 4 years respectively (t‐test <0.005). The marker levels were expressed as multiples of the gestation‐specific normal medians. The IVF group had lower PAPP‐A (0.78 vs 1.03, t‐test P < 0.05) and higher NT (1.14 vs 1.01, t‐test P < 0.05) values, respectively. All the other markers were similar for both groups. On the basis of the integrated test, a higher rate of IVF pregnancies were defined as being screen‐positive (6.1% vs 3.7%), although the values did not reach a level of statistical significance.

Conclusions

Since NT alone yielded the same FPR as the integrated test, the option of various sonographic screening combinations in this group warrants further investigation. Copyright © 2004 John Wiley & Sons, Ltd.
Trisomy 13 mosaicism: study of serial cytogenetic changes in a case from early pregnancy to infancy
Authors: Chen Ming , Yeh Guang‐Perng , Shih Jin‐Chung , Wang Bao‐Tyan
Published: February 2004

We report a patient whose chorionic villus sampling showed a nonmosaic trisomy 13 [46,XX,der(13;13)(q10;q10)]. Subsequent amniocentesis and cordocentesis showed varying percentages of abnormal cells (77 and 78% in two amniocentesis; 14% in cordocentesis) and mosaic trisomy 13 was impressed. Prenatal fetal ultrasound scanning revealed only mild structural abnormalities (echogenic cardiac foci, transient lemon head, transient skin oedema). The mother chose to continue the pregnancy. Karyotyping of the cord blood, peripheral blood, umbilical cord, urine, and chorion were performed postpartum. The process of correction appeared to exist in the placenta (indirect evidence from coexistence of trisomy 13 [46,XX,der(13;13)(q10,q10)], euploidy [46,XX], aneuploidy [46,XX,–13, +mar], and monosomy 13 [45,XX,–13] in the chorion at birth). The baby had survived beyond eight months of age at the time of submission. Few structural abnormalities except low‐set ears, absence of the 12th rib, and cardiomegaly with ventricular septal defect, were noted postnatally. The growth reached 95th percentile at the age of one month. Development milestones were not delayed at serial evaluations. Her ventricular septal defect was corrected surgically at the age of six months. Karyotypes of her skin fibroblasts, blood lymphocytes, and cardiac tissue were all normal [46,XX] at the time of surgery. Difficulties of the genetic counseling are also discussed. Copyright © 2004 John Wiley & Sons, Ltd.
ROC analysis of an erythroblast morphologic scoring system to improve identification of fetal cells in maternal blood
Authors: Cha Dong‐Hyun , Farina Antonio , Bianchi Diana W. , Johnson Kirby L.
Published: February 2004

Objectives

Nucleated red blood cells are used in research settings as a target cell type for investigations of noninvasive prenatal diagnosis, and these cells have a characteristic nuclear morphology and hemoglobin staining pattern that makes them distinguishable from maternal cells. Recently, we developed an erythroblast scoring system based on these characteristics. Here, we employ statistical analyses to further characterize the utility of this scoring system.

Methods

A total of 170 nucleated red blood cells isolated from peripheral blood of four women undergoing elective termination of a trisomy 21 male fetus were analyzed. Each of the four scoring system parameters, whose values range from 0 to 3 points, served as an independent variable to determine its significance for the correct identification of a cell as fetal or maternal. A logistic regression was used as a multivariable statistical tool.

Results

Forty‐four patterns of the four parameters were found in the overall series. Some patterns were exclusively associated with maternal cells (e.g. 1‐1‐1‐1 and 1‐1‐2‐2), and others were exclusively associated with fetal cells (e.g. 3‐2‐2‐2 and 3‐2‐3‐2). A detection rate of 73.9% at a false‐positive rate of 5% resulted from a random simulation model performed with a 1:5 case:control matched set. The variables most predictive of a cell being fetal were gamma hemoglobin staining intensity of cytoplasm and nuclear roundness.

Conclusions

The modified scoring system presented here improves upon the previously reported, unmodified erythroblast scoring system. These statistical analyses suggest that the scoring system is a promising method that aids in distinguishing fetal and maternal NRBCs for prenatal diagnostic applications and that it may be amenable to automated microscopy by applying the discrete morphological parameters as computational classifiers. Copyright © 2004 John Wiley & Sons, Ltd.
Prenatal diagnosis of mos46,X,del(Y)(q11.2)/45,X by cytogenetic and molecular studies with multiplex STR analysis
Authors: Hwa Hsiao‐Lin , Ko Tsang‐Ming , Chang Yih‐Yuan , Huang Chien‐Hao , Su Yi‐Ning , Tseng Li‐Hui , Hsieh Fon‐Jou
Published: February 2004

Objectives

To present the prenatal diagnosis of a fetus of mos46,X,del(Y)(q11.2)/45,X by cytogenetic and molecular analysis.

Case and Methods

A 35‐year‐old pregnant woman came to our hospital for amniocentesis, and fetal chromosomal aberrations with mos46,X, + mar/45,X were found. Fluorescence in situ hybridization revealed the existence of a Y centromere on the marker chromosome. Analysis with six pairs of short tandem repeat markers showed that the genomic DNA extracted from the uncultured amniotic fluid cells contained a deletion of Yq11.1‐Yq11.2. Spermatogenesis loci of the Y chromosome were studied using four sets of multiplex PCR. The proximal two markers DYS271 and KALY were present and the other 16 distal markers were deleted. No deletion was noted in the Y chromosome of the father.

Results

Cytogenetic and molecular analyses revealed deletions of AZFb, d, and c regions on Yq11.2‐Yqter in the fetal Y chromosome. Postmortem examination of the fetus showed a grossly normal male fetus with normal external genitalia and testes.

Conclusion

The present report demonstrates that molecular analysis using polymorphic microsatellite markers and multiplex PCR is a useful complement to cytogenetic methods for the identification and the characterization of Y‐chromosomal deletions. Copyright © 2004 John Wiley & Sons, Ltd.
Rheological and physical properties of aliphatic hyperbranched polyesters
Authors: Luciani André , Plummer Christopher J. G. , Nguyen Tuan , Garamszegi László , Månson Jan‐Anders E.
Published: February 2004

The effects of the size (pseudo‐generation number) and nature of end groups on physical and rheological properties were investigated for a series of hyperbranched polyesters based on an ethoxylated pentaerythritol core and 2,2‐bis‐(hydroxymethyl)propionic acid repeat units. The observed linear dependence of the melt viscosity on the molar mass in the high pseudo‐generation‐number limit indicated that entanglement effects were substantially absent. Moreover, the marked influence of end capping of the end groups on the physical and rheological properties suggested that intermolecular interactions were dominated by contacts between the outer shells of the molecules, in which the end groups were assumed to be concentrated. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1218–1225, 2004
Crystallization behavior of dynamically cured polypropylene/epoxy blends
Authors: Jiang Xueliang , Zhang Yong , Zhang Yinxi
Published: February 2004

Dynamically cured polypropylene (PP)/epoxy blends compatibilized with maleic anhydride grafted PP were prepared by the curing of an epoxy resin during melt mixing with molten PP. The morphology and crystallization behavior of dynamically cured PP/epoxy blends were studied with scanning electron microscopy, differential scanning calorimetry, and polarized optical microscopy. Dynamically cured PP/epoxy blends, with the structure of epoxy particles finely dispersed in the PP matrix, were obtained, and the average diameter of the particles slightly increased with increasing epoxy resin content. In a study of the nonisothermal crystallization of PP and PP/epoxy blends, crystallization parameter analysis showed that epoxy particles could act as effective nucleating agents, accelerating the crystallization of the PP component in the PP/epoxy blends. The isothermal crystallization kinetics of PP and dynamically cured PP/epoxy blends were described by the Avrami equation. The results showed that the Avrami exponent of PP in the blends was higher than that of PP, and the crystallization rate was faster than that of PP. However, the crystallization rate decreased when the epoxy resin content was greater than 20 wt %. The crystallization thermodynamics of PP and dynamically cured PP/epoxy blends were studied according to the Hoffman theory. The chain folding energy for PP crystallization in dynamically cured PP/epoxy blends decreased with increasing epoxy resin content, and the minimum of the chain folding energy was observed at a 20 wt % epoxy resin content. The size of the PP spherulites in the blends was obviously smaller than that of PP. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1181–1191, 2004
Exploitation of introducing of catalytic centers into layer galleries of layered silicates and related epoxy nanocomposites. I. Epoxy nanocomposites derived from montmorillonite modified with catalytic surfactant‐bearing carboxyl groups
Authors: Guo Baochun , Ouyang Xing , Cai Changgeng , Jia Demin
Published: February 2004

Montmorillonite (MMT) was modified with the acidified cocamidopropyl betaine (CAB) and the resulting organo‐montmorillonite (O‐MMT) was dispersed in an epoxy/methyl tetrahydrophthalic anhydride system to form epoxy nanocomposites. The intercalation and exfoliation behavior of the epoxy nanocomposites were examined by X‐ray diffraction and transmission electron microscopy. The curing behavior and thermal property were investigated by in situ Fourier transform infrared spectroscopy and DSC, respectively. The results showed that MMT could be highly intercalated by acidified CAB, and O‐MMT could be easily dispersed in epoxy resin to form intercalated/exfoliated epoxy nanocomposites. When the O‐MMT loading was lower than 8 phr (relative to 100 phr resin), exfoliated nanocomposites were achieved. The glass‐transition temperatures (Tg's) of the exfoliated nanocomposite were 20 °C higher than that of the neat resin. At higher O‐MMT loading, partial exfoliation was achieved, and those samples possessed moderately higher Tg's as compared with the neat resin. O‐MMT showed an obviously catalytic nature toward the curing of epoxy resin. The curing rate of the epoxy compound increased with O‐MMT loading. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1192–1198, 2004
Reversible nonlinear conduction in high‐density polyethylene/acetylene carbon black composites at various ambient temperatures
Authors: Song Yihu , Zheng Qiang , Yi Xiao‐Su
Published: February 2004

The reversible nonlinear conduction (RNC) in of high‐density polyethylene/acetylene carbon black composites with different degrees of crosslinking was studied above room temperature and below the melting point of high‐density polyethylene (HDPE). The experimental current density‐electric field strength curves can be overlapped onto a master curve, suggesting that the microscopic mechanisms for the appearance of RNC exist regardless of the ambient temperature and the crosslinking degree of the HDPE matrix. The relationship between the crossover current density and the linear conductivity can be explained in the framework of the dynamic random‐resistor‐network model. According to these results, two electron‐tunneling models are suggested to interpret the microscopic conduction behavior. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1212–1217, 2004
Poisson's ratio of cellulose Iβ and cellulose II
Authors: Nakamura Ken'Ichi , Wada Masahisa , Kuga Shigenori , Okano Takeshi
Published: February 2004

Poisson's ratios of cellulose Iβ and cellulose II were determined for purified ramie and mercerized samples by X‐ray diffractometry. Poisson's ratio was 0.38 for [200]/[004] of cellulose Iβ and 0.30 for [200]/[004] and 0.46 for [110]/[004] of cellulose II. The smaller [200]/[004] Poisson's ratio for cellulose II could be ascribed to closer intermolecular association through hydrogen bonding and van der Waals forces. Poisson's ratio for [11¯0]/[004] of cellulose II was estimated to be negative. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1206–1211, 2004
Estimation of the agglomeration structure for conductive particles and fiber‐filled high‐density polyethylene through dynamic rheological measurements
Authors: Wu Gang , Zheng Qiang
Published: February 2004

A study on the correlation between electrical percolation and viscoelastic percolation for carbon black (CB) and carbon fiber (CF) filled high‐density polyethylene (HDPE) conductive composites was carried out through an examination of the filler concentration (ϕ) dependence of the volume resistivity (ρ) and dynamic viscoelastic functions. For CB/HDPE composites, when ϕ was higher than the modulus percolation threshold (ϕG ∼ 15 vol %), the dynamic storage modulus (G′) reached a plateau at low frequencies. The relationship between ρ and the normalized dynamic storage modulus (Gc′/Gp′, where Gc′ and Gp′ are the dynamic storage moduli of the composites and the polymer matrix, respectively) was studied. When ϕ approached a critical value (ϕr), a characteristic change in Gc′/Gp′ appeared. The critical value (Gc′/G′p)c was 9.80, and the corresponding ϕr value was 10 vol %. There also existed a ϕ dependence of the dynamic loss tangent (tan δ) and a peak in a plot of tan δ versus the frequency when ϕ approached a loss‐angle percolation (ϕδ = 9 vol %). With parameter K substituted for A, a modified Kerner–Nielson equation was obtained and used to analyze the formation of the network structure. The viscoelastic percolation for CB/HDPE composites could be verified on the basis of the modified equation, whereas no similar percolation was found for CF/HDPE composites. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1199–1205, 2004
Effect of composition on the width of the calorimetric glass transition in polymer–solvent and solvent–solvent mixtures
Authors: Savin Daniel A. , Larson Anne M. , Lodge Timothy P.
Published: February 2004

The calorimetric glass‐transition temperature (Tg) and transition width were measured over the full composition range for solvent–solvent mixtures of o‐terphenyl with tricresyl phosphate and with dibutyl phthalate and for polymer–solvent mixtures of polystyrene with three dialkyl phthalates. Tg shifted smoothly to higher temperatures with the addition of the component with the higher Tg for both sets of solvent–solvent mixtures. The superposition of the differential scanning calorimetry traces showed almost no composition dependence for the width of the transition region. In contrast, the composition dependence of Tg in polymer–solvent mixtures was different at high and low polymer concentrations, and two distinct Tg's were observed at intermediate compositions. These results were interpreted in terms of the local length scale and associated local composition variations affecting Tg. The possible implications of these results for the dynamics of miscible polymer blends were examined. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1155–1163, 2004
Crystallization regime behavior of poly(pentamethylene terephthalate)
Authors: Wu Pi‐Ling , Woo E. M.
Published: February 2004

Poly(pentamethylene terephthalate) (PPT), a less studied aryl polyester, was synthesized by polycondensation and characterized by 1H NMR and gel permeation chromatography. The crystallization kinetics were investigated by means of differential scanning calorimetry and polarized light microscopy. The average value of the Avrami exponent was calculated to be 2.9, which indicated an athermal nucleation process followed by three‐dimensional crystal growth. The kinetics of spherulitic growth of PPT were analyzed with the Lauritzen–Hoffman (L–H) secondary nucleation theory, and the nucleation constants (Kg) for regimes II and III were thus determined from the slope of the L–H plot with an activation energy (U*) of 3500 cal/mol. The validity of the U* value was examined. Meanwhile, the existence of a transition from regime II to regime III at 95 °C was determined, and the value of Kg(III)/Kg(II) was 2.04. The equilibrium melting temperature of PPT was estimated to be 149.4 °C with the linear Hoffman–Weeks extrapolation method. The lateral surface free energy, fold surface free energy, and work of chain folding were estimated. These thermodynamic properties of PPT were then compared to those of other terephthalic polyesters. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1265–1274, 2004
Evidence for coupling and decoupling of parts of macromolecules by temperature‐modulated calorimetry
Authors: Wunderlich Bernhard
Published: February 2004

Equilibrium crystals of linear macromolecules have an extended‐chain macroconformation. They can melt at the equilibrium melting temperature, whereas crystallization needs considerable supercooling, even in the presence of crystal nuclei, making the overall phase transition irreversible. The same molecules with a metastable, chain‐folded macroconformation may have a large amount of specific reversibility, that is, a fraction of the same polymer molecule that melts irreversibly may also show decoupled, reversible melting. The overall metastable, nanophase structure of such semicrystalline polymers may thus support local equilibria. The tool for the quantitative analysis is quasi‐isothermal temperature‐modulated calorimetry that can separate reversible from irreversible processes. A major review of the study of crystals of more than 20 polymers has been published. On the basis of this extensive body of information, a first discussion of decoupling of parts of macromolecules is attempted and linked to previous studies of phase equilibria. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1275–1288, 2004
Inclusion complex formation between α,γ‐cyclodextrins and organic–inorganic star‐shaped poly(ethylene glycol) from an octafunctional silsesquioxane core
Authors: Huang Junchao , Li Xu , Lin Tintin , He Chaobin , Yi Mya Khine , Xiao Yang , Li Jun
Published: February 2004

A series of organic–inorganic star‐shaped poly(ethylene glycol)s from octafunctional silsesquioxane (POSS) cores were synthesized by allylation and hydrosilylation, and they were found to form crystalline inclusion complexes with α,γ‐cyclodextrins. The results from X‐ray diffraction, cross‐polarity/magic‐angle‐spinning 13C NMR, differential scanning calorimetry, and Fourier transform infrared suggested that a channel‐type structure was established in the inclusion complexes. The characterization results also revealed that the segments of poly(ethylene glycol) arms near the POSS cores were uncovered by the cyclodextrins, whereas the cyclodextrins were closely packed along the remaining portion of the poly(ethylene glycol) arms. Molecular dynamic simulation in a Dreiding force field with Cerius2 software gave comparable results. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1173–1180, 2004
Novel urethane/epoxy resin hybrid materials using a moisture‐curing system
Authors: Okuhira Hiroyuki , Iwamoto Nobuaki , Ochi Mitsukazu , Takeyama Hidekazu
Published: February 2004

Novel curing systems of a urethane/epoxy resin [diglycidyl ether of bisphenol A (DGEBA)] alloy using the moisture‐latent hardener ketimine (K‐systems) were investigated on the DGEBA‐rich side and were compared with aromatic diamine curing systems (A‐systems). Almost all the added DGEBA was separated from the polyurethane matrix and dispersed as 2–10‐μm‐diameter particles after curing in the A‐systems. Therefore, DGEBA did not act as a reinforcing agent for the polyurethane matrix. However, 50% of the added DGEBA was dispersed as particles with a diameter of 1–4 μm, and the other 50% was incorporated into the polyurethane matrix in the novel K‐systems. Therefore, the polyurethane matrix in the K‐systems should be reinforced effectively by both incorporated and finely dispersed DGEBA and should result in significant improvements in the stress–strain properties. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1137–1144, 2004
Controlled melting of individual, nano‐meter‐sized, polymer crystals confined in a block copolymer mesostructure
Authors: Vasilev Cvetelin , Heinzelmann Harry , Reiter Günter
Published: February 2004

We demonstrate a possibility to create custom‐made surface patterns on multiple length scales by melting selected nano‐meter‐sized polymer crystals confined in a highly ordered, spherical mesostructure of a hydrogenated poly(butadiene‐block‐ethylene oxide) (PBh‐b‐PEO) block copolymer. With heatable probes of an atomic force microscope as a heat source, we succeeded to provide highly locally the thermal energy necessary to individually melt such crystals. Besides this possibility for modification of surface properties, we performed detailedin situstudies of thermally induced reorganization processes and subsequent melting of polymer crystals in confined volumes of a block copolymer mesostructure. Close to the melting point, the stability of the confined crystals could be improved by annealing. In addition, the crystal size increased at the expense of already‐molten crystals, indicating diffusion of PEO blocks across the highly incompatible PBhmatrix. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1312–1320, 2004
Applicability of the transient plane source method to measure the thermal conductivity of low‐density polyethylene foams
Authors: Almanza O. , Rodríguez‐Pérez M. A. , De Saja J. A.
Published: February 2004

The thermal conductivity at constant pressure of a collection of crosslinked, closed‐cell polyethylene foams were measured at room temperature with the transient plane source (TPS) method. The experimental results were compared with those determined by a standard steady‐state technique. The results showed that the values measured by the TPS method follow the same trends as those measured by a heat‐flow meter. Therefore, with the TPS technique it is possible to observe the influence of structural characteristics such as cell size, black carbon content in foams, density, and so forth on thermal conductivity. However, the values obtained by the transient method were approximately 20% higher than those given by the standard method. Possible reasons for these variations are discussed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1226–1234, 2004
Large enhancement of the ionic conductivity in an electron‐beam‐irradiated [poly(ethylene glycol)]xLiClO4 solid polymer electrolyte
Authors: Singh Th. Joykumar , Ganeshsanjeev  , Siddappa K. , Bhat S. V.
Published: February 2004

The effect of electron‐beam (4–8 MeV) irradiation on the ionic conductivity of a solid polymer electrolyte, poly(ethylene glycol) complexed with LiClO4, was studied. A large enhancement of the conductivity of nearly two orders of magnitude was observed for the highest dose of irradiation (15 kGy) used. The samples were characterized with differential scanning calorimetry, matrix‐assisted laser desorption/ionization, and electron spin resonance spectroscopy. Although no free radicals were present in the irradiated samples, a decrease in the glass‐transition temperature and an increase in the amorphous fraction were observed. Even though pure poly(ethylene glycol) underwent considerable fragmentation, unexpectedly, no significant fragmentation was observed in the polymer–salt complexes. The enhancement of the conductivity was attributed to an increase in the amorphous fraction of the systems and also to an increase in the flexibility of the polymer chains due to the irradiation. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1299–1311, 2004
Miscibility and surface properties of fluorinated copolymer blends involving hydrogen‐bonding interactions
Authors: Huang H. L. , Goh S. H. , Lai Doreen M. Y. , Wee A. T. S. , Huan C. H. A.
Published: February 2004

The miscibility and underlying hydrogen‐bonding interactions of blends of a fluorinated copolymer containing pyridine and a nonfluorinated copolymer containing methacrylic acid were studied with differential scanning calorimetry (DSC), transmission Fourier transform infrared (TX‐FTIR) spectroscopy, and X‐ray photoelectron spectroscopy (XPS), whereas the surface properties of the blends were investigated with contact‐angle measurements, time‐of‐flight secondary‐ion mass spectroscopy, XPS, and attenuated total reflectance Fourier transform infrared spectroscopy. DSC studies showed that the presence of a sufficient amount of 4‐vinylpyridine units in the fluorinated copolymer produced miscible blends with the nonfluorinated copolymer containing methacrylic acid. TX‐FTIR and XPS showed the existence of pyridine–acid interpolymer hydrogen‐bonding interactions. Even though the anchoring effect of hydrogen bonding hindered the migration of the fluorinated component to the blend surface, it could not completely eliminate the surface enrichment of the fluorinated component and the surface rearrangement of the fluorinated pendant chain. The air–blend interface was mainly occupied by the fluorinated pendant chain, and the surface energies of the blends were extremely low, even with only 1.5 wt % of the fluorinated component in the blends. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1145–1154, 2004
Structure and mechanical properties of talc‐filled blends of polypropylene and styrenic block copolymers
Authors: Denac Matjaž , Musil Vojko , Šmit Ivan
Published: February 2004

The structure–property relationships of isotactic polypropylene (iPP)/styrenic block copolymer blends filled with talc were examined by optical and scanning electron microscopy, wide‐angle X‐ray diffraction, and tensile‐ and impact strength measurements. The composites were analyzed as a function of the poly(styrene‐b‐ethylene‐co‐propylene) diblock copolymer (SEP) and the poly(styrene‐b‐butadiene‐b‐styrene) triblock copolymer (SBS) content in the range from 0 to 20 vol % as elastomeric components and with 12 vol % of aminosilane surface‐treated talc as a filler. Talc crystals incorporated in the iPP matrix accommodated mostly plane‐parallel to the surface of the samples and strongly affected the crystallization process of the iPP matrix. The SBS block copolymer disoriented plane‐parallel talc crystals more significantly than the SEP block copolymer. The mechanical properties depended on the final phase morphology of the investigated iPP blends and composites and supermolecular structure of the iPP matrix because of the interactivity between their components. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1255–1264, 2004
Modeling the polymerization behavior of vegetable‐oil‐derived macromonomers in solution by computer simulation
Authors: Diamond Keri L. , Pandey Ras B. , Thames Shelby F.
Published: February 2004

A computer simulation model was used to study the polymerization behavior of multifunctional, vegetable‐oil‐derived macromonomers. Mixtures of olefins (A) and acrylates (B) were initially randomly dispersed on a cubic lattice of size L3. Interactions between A, B, and the solvent sites were considered with respect to their relative proximity, mobility and some kinetics. The Metropolis algorithm was used to move each functional group (A and B). Stirred and equilibrated samples were prepared before reaction initiation. Reactions between the functional groups were implemented with a bonding probability kαβ, which was subject to the availability of unsaturated bonds. The conversion factor, that is, the growth of A–B bonds, was analyzed for a range of polymer concentrations (p = 0.2–0.8) with different reaction probabilities (i.e., kαβ). A stirred (nonequilibrium) sample did not allow sufficient time for the functional groups to arrange according to the interaction parameters. Therefore, the simulations were rerun with equilibrated samples and were found to be consistent with experimental observations. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1164–1172, 2004
Electric‐field‐induced molecular alignment of side‐chain liquid‐crystalline polyacetylenes containing biphenyl mesogens
Authors: Geng Jianxin , Zhou Enle , Li Gao , Lam Jacky Wing Yip , Tang Ben Zhong
Published: February 2004

Electric‐field‐induced molecular alignments of side‐chain liquid‐crystalline polyacetylenes [{HCC[(CH2)mOCO‐biph‐OC7H15]}, where biph is 4,4′‐biphenylyl and m is 3 (PA3EO7) or 9 (PA9EO7)] were studied with X‐ray diffraction and polarized optical microscopy. An orientation as high as 0.84 was obtained for PA9EO7. Furthermore, the molecular orientation of PA9EO7 was achieved within a temperature range between the isotropic‐to‐smectic A transition temperature and 115 °C, and this suggested that the orientational packing was affected by the thermal fluctuation of the isotropic liquid and the mobility of the mesogenic moieties. The maximum achievable orientation for PA9EO7 was much greater than that for PA3EO7. This was the first time that the electric‐field‐induced molecular orientation of a side‐chain liquid‐crystalline polymer with a stiff backbone was studied. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1333–1341, 2004
Phase behavior of modified montmorillonite– poly(ϵ‐caprolactone) nanocomposites
Authors: Pucciariello Rachele , Villani Vincenzo , Belviso Sandra , Gorrasi Giuliana , Tortora Mariarosaria , Vittoria Vittoria
Published: February 2004

The thermal behavior and overall isothermal crystallization kinetics of a series of organophilic modified montmorillonite–poly(ϵ‐caprolactone) nanocomposites were investigated. In general, the thermal behavior was influenced more by the type of dispersion than by the clay content. For nanocomposites in which silicate platelets were predominantly dispersed in the polymer matrix to give exfoliated structures, the thermal properties were improved with respect to those of neat poly(ϵ‐caprolactone), whereas in those cases in which simply intercalated structures were attained, the thermal properties regularly decayed as the clay content increased. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1321–1332, 2004