bluuebunny/crossref_metadata_2025_split huggingface dataset:
New polymer syntheses. CIX. Biodegradable, alternating copolyesters of terephthalic acid, aliphatic dicarboxylic acids, and alkane diols
Authors: Shaik Abbas‐Ali , Richter Martin , Kricheldorf Hans R. , Krüger Ralph‐P. 
Published: August 2002

AbstractCopolyesters with an alternating sequence of terephthalic acid and aliphatic dicarboxylic acids were prepared with three different methods. First, dicarboxylic acid dichlorides were reacted with bis(2‐hydroxyethyl)terephthalate (BHET) in refluxing 1,2‐dichlorobenzene. Second, the same monomers were polycondensed at 0–20 °C in the presence of pyridine. Third, dicarboxylic acid dichlorides and silylated BHET were polycondensed in bulk. Only this third method gave satisfactory molecular weights. Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry revealed that the copolyesters prepared by the pyridine and silyl methods might have contained considerable fractions of cyclic oligoesters and polyesters despite the absence of transesterification and backbiting processes. The alternating sequences and thermal properties were characterized with 1H NMR spectroscopy and differential scanning calorimetry measurements, respectively. In agreement with the alternating sequence, all copolyesters proved to be crystalline, but the crystallization was extremely slow [slower than that of poly(ethylene terephthalate)]. A second series of alternating copolyesters was prepared by the polycondensation of silylated bis(4‐hydroxybut‐ yl)terephthalate with various aliphatic dicarboxylic acid dichlorides. The resulting copolyesters showed significantly higher rates of crystallization, and the melting temperatures were higher than those of the BHET‐based copolyesters. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3371–3382, 2001
Ring‐opening polymerization of ϵ‐caprolactone by iodine charge‐transfer complex
Authors: De Queiroz Alvaro A. A. , França Écio J. , Abraham Gustavo A. , Román Julio S. 
Published: August 2002

AbstractThe ring‐opening polymerization of ϵ‐caprolactone (ϵ‐CL) catalyzed by iodine (I2) was studied. The formation of a charge‐transfer complex (CTC) among triiodide, I, and ϵ‐CL was confirmed with ultraviolet–visible spectroscopy. The monomer ϵ‐CL was polymerized in bulk using I2as a catalyst to form the polyester having apparent weight‐average molecular weights of 35,900 and 45,500 at polymerization temperatures of 25 and 70 °C, respectively. The reactivity of both, ϵ‐CL monomer and ϵ‐CL:I2CTC, was interpreted by means of the potential energy surfaces determined by semiempirical computations (MNDO‐d). The results suggest that the formation of the ϵ‐CL:I2CTC leads to the ring opening of the ϵ‐CL structure with the lactone protonation and the formation of a highly polarized polymerization precursor (ϵ‐CL)+. The band gaps approximated from an extrapolation of the oligomeric polycaprolactone (PCL) structures were computed. With semiempirical quantum chemical calculations, geometries and charge distributions of the protonated polymerization precursor (ϵ‐CL)+were obtained. The calculated band gap (highest occupied molecular orbit/lowest unoccupied molecular orbit differences) agrees with the experiment. The analysis of the oligomeric PCL isosurfaces indicate the existence of a weakly lone pair character of the CO and CO bonds suggesting a ϵ‐CL ring‐opening specificity. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 714–722, 2002
Probing multiple melting behaviors in poly(ethylene naphthalene 2,6‐dicarboxylate) with different thermal histories by simultaneous wide‐angle and small‐angle X‐ray scattering
Authors: Denchev Z. , Nogales A. , Šics I. , Ezquerra T. A. , Baltá‐Calleja F. J. 
Published: August 2002

AbstractA simultaneous wide‐angle and small‐angle X‐ray scattering study of two poly(ethylene naphthalene 2,6‐dicarboxylate) samples crystallized from the glassy state at different annealing temperatures for different annealing times was carried out with synchrotron radiation. Either single or dual melting was induced in the samples, as confirmed by differential scanning calorimetry (DSC). The correlation function and interface distribution function were calculated to evaluate microstructural parameters such as the long spacing, the thickness of the amorphous and crystalline phases, and the width of the size distributions. The sample with dual melting behavior exhibited an abrupt increase of all microstructural parameters at temperatures above the melting of the lowest endotherm, whereas the sample revealing a single melting endotherm did not show such a sudden change. This finding agrees with the concept that the appearance of two melting peaks in DSC traces can be explained by the dual lamellar stacking model. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 881–894, 2001
Compatibilization efficiency of styrene–butadiene multiblock copolymers in PS/PP blends
Authors: Hlavatá D. , Horák Z. , Lednický F. , Hromádková J. , Pleska A. , Zanevskii Yu. V. 
Published: August 2002

AbstractThe compatibilizing effect of di‐, tri‐, penta‐, and heptablock (two types) copolymers with styrene and butadiene blocks was studied in polystyrene/polypropylene (PS/PP) 4/1 blends. The structure of PS/PP blends with the addition of 5 or 10 wt % of a block copolymer (BC) was determined on several scale levels by means of transmission electron microscopy (TEM) and small‐angle X‐ray scattering (SAXS). The results of the structure analysis were correlated with measured stress‐transfer properties: elongation at break, impact, and tensile strength. Despite the fact that the molar mass of the PS blocks in all the BCs used was about 10,000, that is, below the critical value M* (∼18,000) necessary for the formation of entanglements of PS chains, all the BCs used were found to be good compatibilizers. According to TEM, a certain amount of a BC is localized at the interface in all the analyzed samples, and this results in a finer dispersion of the PP particles in the PS matrix, the effect being more pronounced with S‐B‐S triblock and S‐B‐S‐B‐S pentablock copolymers. The addition of these two BCs to the PS/PP blend also has the most pronounced effect on the improvement of mechanical properties of these blends. Hence, these two BCs can be assumed to be better compatibilizers for the PS/PP (4/1) blend than the S‐B diblock as well as both S‐B‐S‐B‐S‐B‐S and B‐S‐B‐S‐B‐S‐B heptablock copolymers. In both types of PS/PP/BC blends (5 or 10 wt % BC), the BC added was distributed between both the PS/PP interface and the PS phase, and, according to SAXS, it maintained a more or less ordered supermolecular structure of neat BCs. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 931–942, 2001
Perfectly‐alternating linear (AB)nmultiblock copolymers: Effect of molecular design on morphology and properties
Authors: Spontak Richard J. , Smith Steven D. 
Published: August 2002

AbstractPerfectly‐alternating linear (AB)nmultiblock copolymers consist ofnAB block pairs covalently linked in an alternating sequence. Although these copolymers can microphase‐order in the same fashion as their lower‐order (n= 1) diblock analogs, the 2(n− 1) biconformational midblocks comprising each copolymer molecule have a considerable impact on microstructural characteristics and bulk properties. We have applied transmission electron microscopy, differential scanning calorimetry (DSC), and extensional rheometry to examine and compare the morphologies and properties of two series of compositionally symmetric (lamellar) poly(styrene‐b‐isoprene)n(SI)n(1 ≤n≤ 4) multiblock copolymers. In one series, chain length was held constant allowing block mass (Mb) to decrease with increasingn. In the second copolymer series,Mbremained relatively invariant. Increasingnin these two series generally promoted reductions in both the lamellar period and upper (styrenic) glass‐transition temperature, but noticeable increases in tensile modulus and yield strength. These observed trends are more pronounced in the copolymer series with constant chain length due to the coupled relationship betweennandMb. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 947–955, 2001
Amphiphilic polymer gel electrolytes. II. Influence of the ethylene oxide side‐chain length on the gel properties
Authors: Gavelin Patrik , Ostrovskii Denis , Adebahr Josefina , Jannasch Patric , Wesslen Bengt 
Published: August 2002

AbstractAmphiphilic polymers consisting of copolymethacrylates carrying about 26 wt % ethylene oxide [(EO)n] side chains of different lengths were used as matrices in gel electrolytes. The gel electrolytes were composed of 30 wt % copolymer and 70 wt % 1 M LiPF6 in a mixture of ethylene carbonate and γ‐butyrolactone (2/1 w/w). The coordination of lithium ions by the (EO)n side chains in competition with the solvent was studied by Raman spectroscopy. A significantly stronger lithium coordination was observed when the gel electrolyte was based on a copolymer carrying (EO)9 units in comparison with copolymers having (EO)1, (EO)2, and (EO)4 units. Despite the observed stronger lithium coordination by (EO)9 units in the gel, the ion conductivity was not significantly lower with respect to the gels based on the other copolymers. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1519–1524, 2001
The influence of hydrogen chloride doping level on the complex refractive indices of anisotropic polyaniline film: Application of a new internal reflection waveguide coupling technique
Authors: Liu Tao , Samuels Robert 
Published: August 2002

AbstractNondestructive three‐dimensional refractive‐index measurements are used for the determination of both crystallinity and orientation in thin polymer films. The prism waveguide coupler is particularly suitable for three‐dimensional isotropic and anisotropic thin‐film studies because of the quantitative character of the information obtained and the ease of data acquisition. It has been limited, however, to measuring the refractive index of optically transparent or weakly absorbing films. This study shows that a modified prism waveguide coupler can be used to determine the complex refractive index over a range from transparent to highly absorbing films from the internally reflected light intensity. Thus, both the refractive index, n, and the extinction coefficient, k, can be obtained. This method is used to determine the anisotropic three‐dimensional n and k values of spin‐coated emeraldine base and hydrogen chloride doped emeraldine salt polyaniline films. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2481–2490, 2001
Factors reported to influence the return to work of cancer survivors: a literature review
Authors: Spelten Evelien R. , Sprangers Mirjam A.G. , Verbeek Jos H.A.M 
Published: August 2002

AbstractAn overview is provided of research into the return to work of cancer survivors, examining both the rate of return to work and factors impacting this return. A series of literature searches was conducted on MEDLINE and PSYCLIT databases for the years 1985–1999. Studies had to focus on the patient's perspective and had to include either the percentage of return to work or factors associated with return to work. Case studies and studies of cancer as an occupational disease were excluded. The search identified 14 studies. The mean rate of return to work was 62% (range 30–93%). The following factors were negatively associated with return to work: a non‐supportive work environment, manual labour, and having head and neck cancer. Sociodemographic characteristics were not associated with return to work. For increasing age, associations were mixed. The increased survival rate of cancer patients warrants attention to the problems survivors may encounter upon their return to work. More systematic research is needed to establish more clearly the relative importance of factors associated with return to work of cancer survivors, which, in turn, would contribute to an increase in the labour‐participation of cancer survivors. Copyright © 2002 John Wiley & Sons, Ltd.
Lung function in diastrophic dysplasia*
Authors: Remes Ville , Helenius Ilkka , Peltonen Jari , Poussa Mikko , Sovijärvi Anssi 
Published: August 2002

AbstractDiastrophic dysplasia (DD) is a rare skeletal dysplasia characterized by short‐limbed short stature, contractures and early degeneration of joints, and spinal deformities such as scoliosis. Mortality is increased in the neonatal period, in part due to tracheo‐ and bronchomalacia. Additionally, spinal deformities are very rigid, decreasing mobility of the chest cage. The aim of our study was to evaluate lung volumes and airway flow dynamics in patients with DD. A total of 31 patients (12 males, 19 females) underwent a detailed clinical examination measurements of standing height PA‐radiography of the spine, flow‐volume spirometry, and body plethysmography. The patients were assigned to two groups: children and adolescents (0–18 years, n = 18) and adults (over 18 years, n = 13).The mean spirometric parameters were mostly within the predicted value range, although the variation was wide. At least one abnormally low spirometry parameter was found in 6 (33%) of the children and adolescents and in 7 (54%) of the adults. Mean forced vital capacity (FVC) was 104% (range 48–163%) of predicted values in the children and adolescents and 95% (58–140%) of the adults. Peak expiratory flow (PEF) values were abnormal in 4 (22%) of the children and adolescents and in 5 (39%) adults. The mean plethysmographic parameters were all within the predicted value range. At least one abnormal plethysmographic value was found in 6 (33%) of the children and adolescents and in 4 (31%) of the adults. Airway resistance (Raw) was significantly higher in the adults than in the children and adolescents (P = 0.016), and was abnormally high in 3 (23%) of the adults. The angle of thoracic or thoracolumbar scoliosis correlated with the percentages of the predicted values of FVC (rs = − 0.66), forced expired volume in 1 sec (FEV1) (rs = − 0.56), and total lung capacity (TLC) (rs = − 0.67). Age correlated with the FEV1/FVC ratio (rs = − 0.41), with the maximal expired flow at 50% FEV (MEF50) values (rs = − 0.55), with the residual volume (RV) values (rs = − 0.47), and with the RV/TLC ratio (rs = − 0.43). Variable bronchial obstruction was found in 1 (6%) child and in 2 (17%) adults.Although the patients with DD had, on average, normal lung volumes, large individual variation occurred. Airway resistance was increased in adults. The angle of scoliosis correlated inversely with lung volume parameters. Pediatr Pulmonol. 2002; 33:277–282. © 2002 Wiley‐Liss, Inc.
Maternal history, sensitization to allergens, and current wheezing, rhinitis, and eczema among children in Costa Rica
Authors: Soto‐Quiros Manuel E. , Silverman Edwin K. , Hanson Lars Å. , Weiss Scott T. , Celedón Juan C. 
Published: August 2002

AbstractLittle is known about the factors associated with asthma, allergic rhinitis, and eczema in Latin American countries. We investigated the relation between potential risk factors and current wheezing, allergic rhinitis, and eczema among 208 Costa Rican children aged 10–13 years participating in phase II of the International Study of Asthma and Allergies in Childhood (ISAAC).The geometric mean ( ± SD) serum total IgE level of children with current wheezing was significantly higher than that of children without current wheezing (533.8 ± 5.2 vs. 144.7 ± 6.0 IU/mL, P < 0.01). In a multivariate analysis, a maternal history of asthma, skin test reactivity (STR) to house dust mites, and STR to Alternaria were significantly associated with current wheezing. Children who had a maternal history of asthma had 2.4 times higher odds of current wheezing than those without maternal history of asthma (95% CI for OR = 1.1–5.3). Sensitization to either house dust mite or Alternaria was associated with 3.3 times increased odds of current wheezing (95% CI for OR for STR to dust mite = 1.6–6.7; 95% CI for OR for STR to Alternaria = 1.1–11.0). In a multivariate analysis, STR to house dust mite and STR to cat dander were significantly associated with allergic rhinitis, and a maternal history of eczema and STR to dog dander were associated with eczema in the child.The interaction between familial factors and lifestyle changes resulting from social reforms implemented 60 years ago may explain the high prevalence of atopic diseases in Costa Rica. Pediatr Pulmonol. 2002; 33:237–243. © 2002 Wiley‐Liss, Inc.
Noninvasive investigation of hepatopulmonary syndrome in children and adolescents with chronic cholestasis
Authors: Santamaria Francesca , Sarnelli Paola , Celentano Luigi , Farina Vincenzo , Vegnente Angela , Mansi Antonio , Montella Silvia , Vajro Pietro 
Published: August 2002

AbstractEarly detection of hepatopulmonary syndrome (HPS) may be delayed because of invasiveness of the diagnostic procedures. In this pilot study, we prospectively investigated the usefulness of determining transcutaneous O2 tension after 100% O2 (TcPO2100) breathing using a transcutaneous hyperoxia test (THT) in 11 children with chronic cholestasis and without primary cardiopulmonary disease. These patients also underwent alveolar‐arterial O2 gradient testing (AaDO2) at an inspired oxygen fraction (FiO2) of 0.21, lung scintiscan, and contrast transthoracic echocardiography (TTE). Three of them had a liver transplantation because of the downhill course of their liver disease and respiratory status.THT transcutaneous O2 tension at 21% FiO2 (TcPO221) was 75 ± 13 mmHg, and increased to 488 ± 106 mmHg after 100% O2 breathing (TcPO2100). Both mean values were not significantly different from those found in 8 age‐matched controls (P = 0.9 and P = 0.5, respectively). However, one patient, in spite of her stable liver function, showed an abnormal TcPO221 and TcPO2100 (45 mmHg and 210 mmHg, respectively). This same subject was also the only patient with abnormalities of AaDO2 (54.2 mmHg; normal value, < 20 mmHg), lung scintiscan (brain/lung ratio of technetium‐99 fixation (B/L SI) = 9, normal value < 1), and TTE, suggesting intrapulmonary vasodilatations and shunts. Given the clinical development of cyanosis and platypnea, all criteria for HPS were fulfilled, and timing of her liver transplantation was therefore accelerated. This resulted in HPS regression.In children with chronic cholestasis, repeated transcutaneous bedside measurements are a rapid and reliable noninvasive test for characterizing the severity of abnormal oxygenation, and may prove useful also in liver posttransplantation monitoring. Pediatr Pulmonol. 2002; 33:374–379. © 2002 Wiley‐Liss, Inc.
Evidence of early systemic activation and transendothelial migration of neutrophils in neonates with severe respiratory distress syndrome
Authors: Sarafidis Kosmas , Drossou‐Agakidou Vasiliki , Kanakoudi‐Tsakalidou Florence , Taparkou Anna , Tsakalidis Christos , Tsandali Chaido , Kremenopoulos Georgios 
Published: August 2002

AbstractSeveral observations imply that the early inflammatory response involving activated neutrophils, tissue macrophages, and cytokines plays an important role in the pathogenesis of neonatal respiratory distress syndrome (RDS) and progression to bronchopulmonary dysplasia (BPD). The aim of this study was to test the hypothesis that changes in circulating neutrophil number and function and plasma levels of cytokines, consistent with neutrophil activation and migration to the tissues, occur during the early stages of neonatal RDS. For this purpose we measured peripheral blood levels of certain immunological parameters that promote neutrophil activation and transendothelial migration. Twenty preterm neonates with severe RDS and 20 healthy infants matched for gestational age were the subjects. The absolute neutrophil count (ANC), and plasma levels of interleukin‐6 (IL‐6), granulocyte colony‐stimulating factor (G‐CSF), and sL‐selectin using an enzyme‐linked immunosorbent assay (ELISA), neutrophil CD11b expression, and respiratory burst activity (RBA) using flow cytometry, were measured within 24 h after birth.The two groups were comparable regarding perinatal characteristics. None of the neonates studied had any clinical or laboratory evidence of infection by the time of blood sampling. The immunological investigation showed that the RDS neonates had significantly lower ANC (P = 0.032), higher expression of the CD11b on neutrophils (P = 0.0065), and higher G‐CSF and IL‐6 plasma levels (P = 0.0047 and P < 0.0001, respectively) in comparison to healthy preterm neonates. The neutrophil RBA and plasma sL‐selectin levels did not differ significantly between the two groups.We conclude that in neonates with severe RDS, there is evidence of a systemic neutrophil activation early in the course of the disease, supporting the view of a contributing role of activated neutrophils in the pathogenesis of RDS. Pediatr Pulmonol. 2001; 31:214–219. © 2001 Wiley‐Liss, Inc.
Insulin‐like growth factors and risk of benign prostatic hyperplasia†
Authors: Chokkalingam Anand P. , Gao Yu‐Tang , Deng Jie , Stanczyk Frank Z. , Sesterhenn Isabell A. , Mostofi F.K. , Fraumeni Joseph F. , Hsing Ann W. 
Published: August 2002

AbstractBACKGROUNDInsulin‐like growth factors (IGFs) have potent growth mitogenic and anti‐apoptotic effects on prostate tissue, whereas IGF binding proteins (IGFBPs) inhibit growth of prostatic tissue. The IGF axis has been implicated in prostate cancer risk, but its role in benign prostatic hyperplasia (BPH) is unclear.METHODSPlasma levels of IGF‐I, IGF‐II, IGFBP‐1, and IGFBP‐3 were determined from the fasting bloods of 206 BPH cases admitted for treatment and 306 randomly selected population controls in Shanghai, China.RESULTSRelative to the lowest tertile, men in the highest tertile of IGF‐I levels had a significantly elevated risk of BPH (odds ratio [OR] = 2.80, 95% confidence interval [95% CI] = 1.60–4.92; Ptrend < 0.001). Results for IGF‐I were more pronounced after adjustment for serum androgens. In contrast, men in the highest IGFBP‐3 tertile had a significantly reduced risk (OR = 0.40; 95% CI = 0.23–0.69; Ptrend < 0.001). No associations of BPH with IGF‐II and IGFBP‐1 were observed.CONCLUSIONAs has been previously observed for prostate cancer, we found that IGF‐I and IGFBP‐3 are associated with BPH risk in China. Further investigation is needed to elucidate the role of the IGF axis in BPH etiology. Prostate 52: 98–105, 2002. Published 2002 Wiley‐Liss, Inc.
Metallothionein isoform 3 expression inhibits cell growth and increases drug resistance of PC‐3 prostate cancer cells
Authors: Dutta Rana , Sens Donald A. , Somji Seema , Sens Mary Ann , Garrett Scott H. 
Published: August 2002

AbstractBACKGROUNDThe third isoform of metallothionein (MT‐3) is overexpressed in prostate cancers and PIN lesions. The expression of MT‐3 is highly variable but appears to correlate to Gleason score. The goal of the present study was to determine the effect of MT‐3 overexpression on the growth of the PC‐3 prostate cancer cell line.METHODSPC‐3 cells were stably transfected with either the MT‐3 or MT‐1E gene. Cell growth was determined by counting DAPI‐stained nuclei, drug resistance by the colony formation assay, MT mRNA expression by reverse transcriptase‐polymerase chain reaction, and MT protein by immunoblot.RESULTSPC‐3 cells that overexpress the MT‐3 gene are growth inhibited compared with either untransfected cells, cells with blank vector, or cells with similar overexpression of the MT‐1E gene. Furthermore, increased chemotherapeutic drug resistance occurred in PC‐3 clones derived from MT‐3– and MT‐1E–transfected cells.CONCLUSIONThe overexpression of MT‐3 can influence the growth and chemotherapeutic drug resistance of the PC‐3 prostate cancer cell line. Prostate 52: 89–97, 2002. © 2002 Wiley‐Liss, Inc.