bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural control of oligomeric methyl silsesquioxane precursors and their thin‐film properties
Authors: Lee Long‐Hua , Chen Wen‐Chang , Liu Wei‐Chih 
Published: August 2002

AbstractOligomeric methyl silsesquioxane (O‐MSSQ) precursors were prepared from methyl trimethoxysilane (MTMS) in a mixed solvent of methyl isobutyl ketone and tetrahydrofuran by variations in the pH and molar ratio of water to MTMS (R1). The molecular structures of O‐MSSQ were controlled by the reaction conditions. At a fixed pH value, the percentage of the end group, SiOCH3, decreased with increasing R1, but that of SiOH increased. With the pH increasing, the ratio of SiOCH3 groups to SiOH groups was enhanced, but ratio of the molecular weights was reduced. The molecular weight distribution was progressively broader as the pH value decreased. These results were explained by the effects of R1 and pH on the hydrolysis and condensation reactions. The prepared O‐MSSQ precursors consisted of mixed cage and network structures. The ratio of cage structures to network structures increased at low pH and high R1 values. Highly uniform thin films were spin‐coated from the O‐MSSQ precursors, and this was followed by multistep curing. The content of cage structures in O‐MSSQ films decreased with increasing curing temperatures, whereas the network content in O‐MSSQ films showed the opposite trend. Such a structural transformation resulted in significant variations in the physical properties. Both the refractive index and dielectric constant decreased with higher cage/network ratios because of changes in the molar volume. The prepared O‐MSSQ has potential applications as a low dielectric constant material. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1560–1571, 2002
Apparent relaxation‐time spectrum cutoff in dilute polymer solutions: An effect of solvent dynamics
Authors: Peterson Steven C. , Echeverría Isabel , Hahn Stephen F. , Strand Deidre A. , Schrag John L. 
Published: August 2002

AbstractThe apparent short time cutoff of the relaxation‐time spectrum at surprisingly long times for polymers in solution is a well known but not yet understood observation. To elucidate its origins we revisit viscoelastic and oscillatory flow birefringence data for solutions and melts of two linear polymers (polystyrene and polyisoprene) and present new measurements of oscillatory flow birefringence of the latter. Previous measurements have suggested that the “flexibility” of both polymers in solution is smaller than in the melt on the basis of the breadth of the relaxation‐time spectrum of the solution as compared with that of the melt. Our new measurements have explored a higher effective frequency range than was previously possible. This has allowed us to observe the effect of the rotational relaxation time of the solvent on the dynamics of the solution at high frequencies. To obtain the polymer global motion contribution, one now needs to subtract from the solution properties a frequency‐dependent complex solvating environment contribution. We show that the decrease in apparent “flexibility” for solutions arises from the presence of a solvent that exhibits a rotational relaxation time and thus simple viscoelastic behavior somewhat near the frequency window of the experiment. Although recent predictions of a model for a chain in a solvent with a single relaxation time are in qualitative agreement with our results, our data suggest that the solution results may reflect the influence of solvent on the development of the “entropic spring” forces at short times. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2860–2873, 2001
Effect of thermal history on the deformation and failure of polyimides
Authors: Lincoln Jason E. , Morgan Roger J. , Shin E. Eugene 
Published: August 2002

AbstractThermal‐processing structure‐property relationships for polyetherimide (PEI), poly(4,4′‐oxydiphenylene pyromellitimide) (POPPI), and phenylethynyl‐terminated imide (PETI‐5) composite matrices are reported from a fundamental perspective. For thermoplastic PEI, deformation and failure depend primarily on free volume as evidenced by moisture‐absorption, mechanical‐property, and mass‐density changes as a function of annealing. The deformation of POPPI can be divided into the following three regimes as a function of annealing temperature: (1) physical aging‐induced glassy state free‐volume decreases, (2) thermally activated microvoid collapse, and (3) chemical degradation. In the case of PETI‐5, macroscopic defects, free volume, and polymer morphology control deformation. The effects of residual crystallinity on deformation are reported, and it is shown that mechanical toughness can be significantly decreased upon annealing below the glass‐transition temperature. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2947–2959, 2001
Water sorption and permeation in chitosan films: Relation between gas permeability and relative humidity
Authors: Despond S. , Espuche E. , Domard A. 
Published: August 2002

AbstractThe water sorption of chitosan has been studied at 20 °C. Water transport is governed by a Fickian process for relative humidities lower than 0.4, and in that range of partial pressures, the diffusion coefficient is concentration‐dependent. At a higher activity, anomalous diffusion is observed. The sorption isotherm is well described by the Guggenheim‐Anderson‐de Boer (GAB) model, and the clustering phenomenon observed at high relative pressures can be studied with the parameters of this model. The water permeability coefficient greatly increases with the relative pressure, and the water plasticization effect leads to a loss of the gas barrier properties under wet conditions. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 3114–3127, 2001
Preparation and properties of graded styrene‐butadiene rubber vulcanizates
Authors: Ikeda Yuko 
Published: August 2002

AbstractStyrene‐butadiene rubber (SBR) vulcanizates with graded network‐chain densities in the thickness direction were prepared by layering and heat pressing the compounding sheets. The effect of the gradient of network‐chain density on the mechanical properties of the graded rubber vulcanizates was investigated in comparison with those of SBR vulcanizates that were prepared from the homogeneous compounding sheets. The matrix with a high network‐chain density exclusively affected the mechanical properties of the graded rubber vulcanizates when the gradient was given in the thickness direction. © 2002 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 358–364, 2002; DOI 10.1002/polb.10096
Influence of microstructure on space charges of polypropylene
Authors: Li Xiang , Du Qiangguo , Kang Jie , Tu Demin 
Published: August 2002

AbstractThe correlation of chemical structure, crystalline morphology, and space charge distribution under a dc electrical field was investigated with three kinds of poly(propylene) (PP) with a different chemical structure, that is, homogeneous PP and block copolymer and random copolymer of PP. The space charge distribution of the samples was prominently affected by their chemical sequence structure and crystalline microstructure. Among samples of different PPs, all isothermally crystallized at 140 °C, the sample of random coPP represents the most well proportional space charge distribution and the smallest number of space charges. The effect of thermal history on the space charge distribution was also investigated by the samples of block coPP. The sample thermally treated at 50 °C clearly represents a better proportional distribution than that at higher temperature of 140 and 100 °C. Subsequent experiments indicate that the better proportional distribution attributes to imperfect and fine sperulites with the fine distribution of the “amorphous” region. The imperfect and fine sperulites originate from the random incorporation of ethylene segments or units into PP chains or from the low annealing temperature, and play an important role in the formation of shallow traps and transportation of space charges. © 2002 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 365–374, 2002; DOI 10.1002/polb.10100
Polydispersity of ethylene sequence length in metallocene ethylene/α‐olefin copolymers. I. Characterized by thermal‐fractionation technique
Authors: Zhang Fajun , Liu Jieping , Fu Qiang , Huang Haiying , Hu Zhijun , Yao Shuang , Cai Xiuyu , He Tianbai 
Published: August 2002

AbstractIn this article, the polydispersity of the ethylene sequence length (ESL) in ethylene/α‐olefin copolymers was studied by atomic force microscopy (AFM) and the thermal‐fractionation technique. The crystal morphology observation by AFM showed that morphology changed gradually with decreasing average ESL from complete lamellae over shorter and more curved lamellae to a granular‐like morphology, and the mixed morphology was observed after stepwise crystallization from phase‐separated melt. This result indicated that the ethylene sequence with different lengths crystallized into a crystalline phase with a different size and stability at the copolymer systems. The thermal‐fractionation technique was used to characterize the polydispersity of ESL. Three of the following statistical terms were introduced to describe the distribution of ESL and the lamellar thickness: the arithmetic mean L̄n, the weight mean L̄w, and the broadness index I = L̄w/L̄n. It was concluded that the polydispersity of ESL could be quantitatively characterized by the thermal‐fractionation technique. The effects of temperature range, temperature‐dependent specific heat capacity Cp of copolymer, and the molecular weight on the results of thermal fractionation were discussed. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 813–821, 2002
Dynamic mechanical and dielectric properties of ORMOCER® incorporating functionalized poly(styrene) latexes
Authors: Cramer S. E. , Quijada‐Garrido I. , Ulrich R. , Barrales‐Rienda J. M. , Spiess H. W. 
Published: August 2002

AbstractOrganically modified aluminosilicate hybrid materials incorporating polystyrene and poly(styrene‐co‐hydroxypropyl acrylate) latexes, (3‐glycidyloxypropyl) trimethoxysilane, and aluminum sec‐butoxide [Al(OsBu)3] were synthesized by a sol–gel process. The bulk materials obtained were macroscopically homogeneous dispersions with good mechanical properties. Dynamic mechanical and dielectric analyses of these new hybrid materials as a function of the Al(OsBu)3 concentration and copolymer composition revealed a series of transitions that represented relaxation processes of the incorporated polymer (glass transition), AlOSi, the SiOSi part of the network, and segmental motion of unreacted Si(CH2)3OCH2CHCH2O chains. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 860–867, 2001
Low‐income women with early‐stage breast cancer: physician and patient decision‐making styles
Authors: McVea Kristine L.S.P. , Minier William C. , Johnson Palensky Jodi E. 
Published: August 2002

AbstractBackground: Poor women have low rates of breast conservation therapy not explained by differences in insurance status or treatment preferences. The purpose of this study was to explore how low‐income women make decisions about breast cancer treatment.Methods: Twenty‐five women diagnosed with early‐stage breast cancer through the Nebraska Every Woman Matters program were interviewed about their experiences selecting treatment options. These interviews were transcribed and then analysed using established qualitative techniques.Results: More than half of the women (n=16) described playing a passive role in decision making. Choice was determined by medical factors or not offered by their physicians. Intense emotional distress affected some women's ability to compare options. The women who did engage in a rational decision‐making process (n=9) based their choices on concerns about body image and fear of recurrence.Conclusions: When presented with a choice, and when able to objectively weigh treatment options, low‐income women base their treatment decisions on the same issues as those of higher income. Whether differences in income strata alter the doctor–patient power dynamic in favor of physician control over decision making, or whether low‐income women are less prepared to engage in a rational deliberative process warrants further study. Copyright © 2001 John Wiley & Sons, Ltd.
Married couples' perspectives on prostate cancer diagnosis and treatment decision‐making
Authors: Boehmer Ulrike , Clark Jack A. 
Published: August 2002

AbstractProstate cancer is a disease of men. But for married men, it is commonly and quite reasonably expected that their wives will be significantly involved in dealing with the disease and its treatment. Yet, there are few data on how wives perceive the diagnosis and their role in responding to it. This study explores men's and their wives' perceptions of the prostate cancer diagnosis and their role in treatment decision‐making. We conducted separate focus group interviews with seven married men with metastatic prostate cancer and their wives. The accounts of receiving the diagnosis and deciding on treatment that were told by the men differed in significant ways from the stories told in the wives' groups. We found that many men do not share their prostate‐related health problems with their wives and some men choose their treatment without much spousal consideration. Our findings suggest that physicians may be in a position to influence how men and their wives interact in reaching a treatment decision. Copyright © 2001 John Wiley & Sons, Ltd.
Predictors of depressive symptomatology of geriatric patients with lung cancer—a longitudinal analysis
Authors: Kurtz M.E. , Kurtz J.C. , Stommel M. , Given C.W. , Given B. 
Published: August 2002

AbstractBackground: Lung cancer is a major health problem throughout the world. It is the leading cause of cancer‐related death in men and women in the USA, with a 5‐year survival rate of only 14%. It has been hypothesized that variables such as physical and social functioning, cancer‐related symptomatology, comorbid conditions, cell type, and treatment are valid predictors of the psychological response to a diagnosis of lung cancer.Methods: As part of a larger longitudinal study, 211 patients, 65 years of age or older, with an incident diagnosis of lung cancer, were recruited from 23 sites within a midwestern state. Repeated measures analysis of variance techniques were used to analyse how age, gender, comorbid conditions, stage of disease, cell type, as well as the time‐dependent variables symptoms, physical functioning, social functioning, and treatment predict depressive symptomatology at four assessments over the first year following diagnosis.Results: Social functioning (p<0.0001), symptoms severity (p<0.0001) and radiation treatment (p=0.017) were significant predictors of depressive symptomatology, with more symptoms and more restricted social functioning generally corresponding to higher levels of depressive symptomatology. Patients who had not received radiation treatment were more depressed than those who had received treatment at least 40 days prior to the interview.Conclusions: At a clinical level of patient care, these findings mandate early identification of psychosocial difficulties experienced, an individualized symptom management plan and the application of other interventions, such as information giving, reassurance and referral to other resources. Copyright © 2002 John Wiley & Sons, Ltd.
Safety of inhaled corticosteroids in children
Authors: Allen David B. 
Published: August 2002

AbstractInhaled corticosteroids (ICS) are now first‐line therapy for persistent asthma in children. The major safety concerns of long‐term ICS therapy for childhood asthma are potential effects on adrenal function, growth, and bone mass. Dosage, type of inhaler device, and individual drug characteristics influence systemic effects of ICS. Sensitive measures of basal adrenal function can show statistically significant changes during ICS therapy, but these do not accurately predict clinically meaningful adrenal axis suppression. Adrenal insufficiency is rare and confined to children receiving high doses of ICS. Dose‐related inhibition of growth has been seen in some short‐ and intermediate‐term studies, but long‐term studies have found no detrimental effect on final height. ICS therapy has not been associated with significant changes in measurements of bone and bone biomarkers, but more studies of high doses and of therapy in adolescents are needed. Overall, although ICS are the most effective anti‐inflammatory treatment available for asthma, high doses of ICS in children are still of concern. The risk of high doses is compounded in children with concomitant allergic conditions that require multiple forms of topical corticosteroids. Benefits of ICS clearly outweigh potential adverse effects and risks associated with poorly controlled asthma. Risk can be minimized by using the lowest effective ICS dose, limiting systemic availability of the drug through proper technique to minimize swallowed drug, and selection of agents with efficient first‐path hepatic inactivation of swallowed drug. Adjuvant treatments can reduce the dose of ICS required for asthma control, allowing a reduction in overall systemic exposure for most children with mild‐to‐moderate persistent asthma. Therefore, these agents should be added to, but should not replace, ICS therapy. Pediatr Pulmonol. 2002; 33:208–220. © 2002 Wiley‐Liss, Inc.
Effect of intravenous antibiotics on exercise tolerance (3‐min step test)) in cystic fibrosis*
Authors: Pike Sarah E. , Prasad S. Ammani , Balfour‐Lynn Ian M. 
Published: August 2002

AbstractMost children with cystic fibrosis (CF) feel better and display more energy after a course of intravenous antibiotics (IVABs), but this is not always reflected by a satisfactory improvement in lung function. We assessed the change in exercise tolerance after treatment with IVABs usingthe 3‐min step test, and compared it with changes in spirometric lung function and arterial oxygen saturation (SaO2). Thirty‐six children (mean age, 13.8 years) were enrolled from two tertiary CF centers during an inpatient stay for IVABs.After 10–14 days of treatment, there was a significant improvement in median FEV1 from 43% to 57% of predicted values (P < 0.0001), and median FVC from 66% to 73% of predicted values (P < 0.0001), while median SaO2 significantly increased from 95% to 96.5% (P < 0.05). This was accompanied by a reduction in resting heart rate (median 118 bpm to 109 bpm, P < 0.005) and subjective breathlessness at rest (median visual analogue score 2.2 to 0.8, P < 0.005). All outcomes of exercise tolerance were improved after IVABs. There was a reduction in maximum heart rate (median 156 bpm to 150 bpm, P < 0.05) and an increase in minimum SaO2 (median 93.5% to 94.5%, P = 0.08) measured during the step test.There was also a reduction in subjective breathlessness (median visualanalogue score of 5.5 to 4.2, P < 0.005) and objective breathlessness (median 15‐count score of 3 to 2, P < 0.0001) measured immediately after the step test.Exercise testing was a useful outcome measure for monitoring effectiveness of inpatient therapy, and complemented spirometry and SaO2 monitoring. The simple ward‐based 3‐min step test was found to be a particularly suitable method for measuring changes in exercise tolerance in childrenwith CF. Pediatr Pulmonol. 2001; 32:38–43. © 2001 Wiley‐Liss, Inc.
Molecular characterization of prostate hyperplasia in prolactin‐transgenic mice by using cDNA representational difference analysis*
Authors: Dillner Karin , Kindblom Jon , Flores‐Morales Amilcar , Pang See‐Tong , Törnell Jan , Wennbo Håkan , Norstedt Gunnar 
Published: August 2002

AbstractBACKGROUNDTransgenic mice overexpressing the rat prolactin (PRL) gene develop a dramatic enlargement of the prostate gland. The objective of this study was to characterize the molecular mechanisms in the prostate of importance for the prostate hyperplasia seen in these transgenic mice.METHODScDNA representational difference analysis (cDNA RDA) was used to isolate differentially expressed transcripts in the prostate hyperplasia of the transgenic mice compared with wildtype littermates. Furthermore, cDNA microarray analysis was used to verify the RDA output.RESULTSHere we report 10 transcripts, some of them described to be involved in proliferation and apoptosis, which are differentially expressed in the enlarged transgenic prostates compared with controls.CONCLUSIONThe identified differentially expressed transcripts presented herein supports molecular similarities between the prostate hyperplasia of PRL‐transgenic mice and human BPH that may contribute to explain the molecular basis of prostate hyperplasia. Prostate 52:139–149, 2002. © 2002 Wiley‐Liss, Inc.
Identification of a novel gene on chromosome 13 between BRCA‐2 and RB‐1
Authors: Schmidt U. , Fiedler U. , Pilarsky C.P. , Ehlers W. , Füssel S. , Haase M. , Faller G. , Sauter G. , Wirth M.P. 
Published: August 2002

AbstractMETHODS AND RESULTSBy differential display we isolated a new cDNA‐fragment, named C13, that is downregulated in malignant prostate tissues. Northern hybridization revealed the fragment to be part of 3.0 and 4.4 kb mRNAs. Fluorescence in situ hybridization, Southern blotting and radiation hybrid mapping demonstrated a chromosomal localization of C13 on 13q12–14 closest to the SHGC‐34125 marker. In the 5% chromosomal environment of C13 we detected changes of the allelic status in 13 of 21 prostate cancers. A downregulation was detected at the mRNA level in patients with advanced carcinoma. The 3.0 kb full length cDNA clone encodes a protein with an open reading frame of 2,202 bp or 733 amino acids. The corresponding protein contains a putative nuclear localization signal, several glutamine clusters and an α‐helix‐rich domain. By in situ RNA hybridization we could demonstrate the mainly epithelial expression of the C13 mRNA in prostatic tissue.CONCLUSIONSThe localization of C13 between the tumor supressor genes BRCA‐2 and RB‐1, the detected allelic imbalances, the downregulation of its mRNA in some prostatic cancer tissues, the epithelial expression and the described protein structure suggest that this gene encodes a protein that may have tumor or metastasis suppressing function in prostate tissue. Prostate 47:91–101, 2001. © 2001 Wiley‐Liss, Inc.