bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of degree of polymerization on gelation and flow processability of poly(vinyl chloride)
Authors: Fujiyama Mitsuyoshi , Kondou Manabu 
Published: March 2004

AbstractThe effect of degree of polymerization (DP) on the gelation and flow processability of poly(vinyl chloride) (PVC) was studied. Sheets with adjusted degree of gelation were prepared by rolling rigid pipe formulation suspension PVC compounds with DPs of 800, 1050 and 1300 by changing the milling temperature. Their degrees of gelation were measured with DSC and their capillary flow properties were measured with a capillary rheometer at 150, 170 and 190°C and the effect of DP on the relation between gelation and flow processabilities was studied. Because of the higher shearing heat during milling, the sample with the higher DP had a higher history temperature and thus tended to show a higher degree of gelation. The viscosity increased as the gelation increased. The dependency of viscosity on DP was higher at higher milling and extrusion temperatures and thus at a higher degree of gelation and a lower shear rate. This was assumed to be attributed to the more prominent uniform molecular flow as against the particle flow. The die swell increased with increasing the milling and extrusion temperatures and hence with increasing the gelation. A sample with a lower DP tended to show a larger die swell and this tendency was even more pronounced at the higher extrusion temperature. The melt fracture easily occurred when a sample with advanced gelation was extruded at low temperature. Whereas at low milling temperatures a sample with the lower DP showed a lower critical shear rate at onset of melt fracture, and thus easily generating melt fracture, at high milling temperatures it showed a higher critical shear rate and hence scarcely generated melt fracture. These experimental results were explained by the fact and concept that a sample with a lower DP shows a higher increase in the gelation during extrusion and/or the slighter feature of particle flow as against the uniform molecular flow at the same gelation level. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1915–1938, 2004
Synthesis and characterization of polyacrylamidegrafted sodium alginate membranes for pervaporation separation of water + isopropanol mixtures
Authors: Toti Udaya S. , Aminabhavi Tejraj M. 
Published: March 2004

AbstractPolyacrylamide‐grafted‐sodium alginate copolymers were prepared by persulfate‐induced radical polymerization by using polymer‐to‐monomer ratios of 2 : 1 and 1 : 1. Polymers were characterized by Fourier transform infrared spectroscopy, differential thermal analysis, and viscosity. Membranes were prepared from the polymers, crosslinked with glutaraldehyde, and used in the pervaporation separation of water + isopropanol mixtures at 30°C. Equilibrium swelling experiments were performed for mixtures containing 10 to 80 mass % of water in the feed. Both the grafted copolymer membranes were ruptured while separating 10 mass % of water in the feed mixture. However, beyond 20 mass % of water in the feed mixture, flux increased with increasing grafting ratio, while selectivity decreased. Pervaporation separation experiments were carried out at 30, 40, and 50°C for 20 mass % of water in the feed mixture. By increasing the temperature, flux increased, whereas selectivity decreased. Arrhenius activation parameters for pervaporation and diffusion decreased with increasing grafting ratio of the membranes. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2030–2037, 2004
Effect of molecular weight on brittle‐to‐ductile transition temperature of polyetherimide
Authors: Sanner Mark A. , Haralur Gurulingamurthy , May Andy 
Published: March 2004

AbstractThe fracture and yield strength of polyetherimide was evaluated over a temperature range of 23 to 140°C for materials with number‐average (Mn) and weight‐average molecular weight (Mw) ranging from 15.6 to 22.8 and 36.6 to 52.3 kg/mol, respectively. The brittle‐to‐ductile transition temperature, where an equal probability exists that an impact will result in a brittle or ductile failure, was determined by evaluating the temperature at which fracture and yield strength are equal. The transition temperature decreased from 155 to 60°C with increasing molecular weight and provided a measure of relative ductility between material samples. As a case study, the practical impact strength of an injection‐molded food service tray was determined at 20°C and correlated with fracture strength as a function of molecular weight. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1666–1671, 2004
Electrochemical polymerization of β‐naphthalene sulfonic acid
Authors: Li Enhua , Huang Zhimin , Shi Gaoquan , Qu Liangti , Zhang Jiaxin 
Published: March 2004

Abstractβ‐Naphthalene sulfonic acid (β‐NSA) has been electrochemically polymerized in a mixed electrolyte of boron trifluoride diethyl etherate (BFEE) solution mixed with a certain amount of trifluoroacetic acid (TFA) or concentrated sulfuric acid (SA). The poly(β‐naphthalene sulfonic acid) (PNSA) film prepared from the medium of BFEE+TFA was partly soluble in methanol. On the other hand, the polymer obtained from the system of BFEE+SA was soluble in water and general polar organic solvents such as methanol, alcohol, and acetone. The structure of PNSA was examined by infrared and UV spectra. Fluorescent spectral studies indicate that the polymer is a blue light emitter with fluorescence quantum efficiency of ∼ 4%. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1939–1944, 2004
Gas phase polymerization of 1,3‐butadiene with supported neodymium‐based catalyst: Investigation of molecular weight
Authors: Ni Xufeng , Li Junfei , Zhang Yifeng , Shen Zhiquan 
Published: March 2004

AbstractThe gas phase polymerization of 1,3‐butadiene (Bd), with supported catalyst Nd(naph)3/Al2Et3Cl3/Al(i‐Bu)3 or/and Al(i‐Bu)2H, was investigated. The polymerization of Bd with neodymium‐based catalysts yielded cis‐1,4 (97.2–98.9%) polybutadiene with controllable molecular weight (MW varying from 40 to 80 × 104 g mol−1). The effects of reaction temperature, reaction time, Nd(naph)3/Al(i‐Bu)3 molar ratio, and cocatalyst component on the catalytic activity and molecular weight of polymers were examined. It was found that there are two kinds of active sites in the catalyst system, which mainly influenced the MW and molecular weight distribution of polybutadiene. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1945–1949, 2004
Preparation and performance of aluminum borate whisker–reinforced epoxy composites. I. Effect of whiskers on processing, reactivity, and mechanical properties
Authors: Liang Guozheng , Hu Xiaolan 
Published: March 2004

AbstractAluminum borate (Al18B4O33) whisker–reinforced composites based on a epoxy resin, which was made up of a trifunctional epoxy resin, TDE 85, and methyl nadic anhydride (MNA), were prepared, and the effects of the whiskers on the processing, reactivity, and typical mechanical properties of the composites were investigated. Two coupling agents, aluminate (DL411A) and borate (BE4), were used to surface treat the whiskers. Results show that the addition of the whiskers does not change the reactivity of the matrix, while increasing the viscosity of the resin, but when the whisker content is less than 5 wt %, the increased viscosity does not obviously influence the processing characteristics of the resin. Mechanical properties are greatly dependent on the chemistry and concentration of the coupling agent for treating the whiskers. A good coupling agent, which has good interaction with the whiskers and the matrix, can effectively improve the compatibility between the whiskers and the matrix, and thus result in great improvement of mechanical properties. BE4 proved to be better than DL411A for treating the whiskers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1950–1954, 2004
Polymerization kinetics and thermal properties of dicyanate/clay nanocomposites
Authors: Kim Dae Su , Lee Kyung Min 
Published: March 2004

AbstractThe polymerization kinetics and thermal properties of dicyanate/clay nanocomposites were investigated. A type of organically modified clay was used as nanometer‐size fillers for the thermosetting dicyanate resin. Differential scanning calorimetry (DSC) was used to study the curing behavior of the dicyanate/clay nanocomposite systems. The polymerization rate of the nanocomposite systems increased with increasing clay content. An autocatalytic reaction mechanism could adequately describe the polymerization kinetics of the dicyanate/clay nanocomposite systems. The polymerization kinetic parameters were determined by fitting the DSC conversion data to the proposed kinetic equation. The glass‐transition temperature of the dicyanate/clay nanocomposites increased with increasing clay content. The thermal decomposition behavior of the dicyanate/clay nanocomposites was investigated by thermogravimetric analysis. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1955–1960, 2004
Bacillus thuringiensis δ‐endotoxin binding to brush border membrane vesicles of rice stem borers
Authors: Alcantara Edwin P. , Aguda Remedios M. , Curtiss April , Dean Donald H. , Cohen Michael B. 
Published: March 2004

AbstractThe receptor binding step in the molecular mode of action of five δ‐endotoxins (Cry1Ab, Cry1Ac, Cry1C, Cry2A, and Cry9C) from Bacillus thuringiensis was examined to find toxins with different receptor sites in the midgut of the striped stem borer (SSB) Chilo suppressalis (Walker) and yellow stem borer (YSB) Scirpophaga incertulas (Walker) (Lepidoptera: Pyralidae). Homologous competition assays were used to estimate binding affinities (Kcom) of 125I‐labelled toxins to brush border membrane vesicles (BBMV). The SSB BBMV affinities in decreasing order was: Cry1Ab = Cry1Ac > Cry9C > Cry2A > Cry1C. In YSB, the order of decreasing affinities was: Cry1Ac > Cry1Ab > Cry9C = Cry2A > Cry1C. The number of binding sites (Bmax) estimated by homologous competition binding among the Cry toxins did not affect toxin binding affinity (Kcom) to both insect midgut BBMVs. Results of the heterologous competition binding assays suggest that Cry1Ab and Cry1Ac compete for the same binding sites in SSB and YSB. Other toxins bind with weak (Cry1C, Cry2A) or no affinity (Cry9C) to Cry1Ab and Cry1Ac binding sites in both species. Cry2A had the lowest toxicity to 10‐day‐old SSB and Cry1Ab and Cry1Ac were the most toxic. Taken together, the results of this study show that Cry1Ab or Cry1Ac could be combined with either Cry1C, Cry2A, or Cry9C for more durable resistance in transgenic rice. Cry1Ab should not be used together with Cry1Ac because a mutation in one receptor site could diminish binding of both toxins. Arch. Insect Biochem. Physiol. 55:169–177, 2004. © 2004 Wiley‐Liss, Inc.
The role of lipoxygenase products on the endocytosis of yolk proteins in insects: Participation of cAMP
Authors: Medeiros M.N. , Mendonça L.H. , Hunter A.L. , Paiva‐Silva G.O. , Mello F.G. , Henze I.P. , Masuda H. , Maya‐Monteiro C.M. , Machado E.A. 
Published: March 2004

AbstractThe participation of eicosanoids and second messengers in the regulation of endocytosis by the ovaries was investigated using the uptake of Rhodnius heme binding protein (RHBP) as an experimental model. The rate of RHBP uptake decreased up to 40% in the presence of BWA4C and NDGA, 5 and 12‐lipoxygenase inhibitors, respectively, suggesting the involvement of lipoxygenase products in endocytosis regulation. Addition of Leukotriene B4 (LTB4; one product of the 5 lipoxygenase pathway) increased in vitro the uptake of RHBP by 30%. The content of cAMP in the Rhodnius' ovaries were monitored after treatment with different eicosanoids and inhibitors of eicosanoids synthesis. The amount of cAMP decreased in the presence of indomethacin (by 50%), while treatment with PGE2 induced an increase of 85% of this messenger in the ovaries. The presence of LTB4 in the medium inhibited in 60% the content of cAMP in the ovaries, while BWA4C induced a 100% increase of this messenger in the ovaries. Addition of 1 μM DBcAMP in the medium resulted in a 30% decrease in the rate of RHBP uptake. Taken together, these data show that cyclooxygenase and lipoxygenase products participate in the control of protein internalization by modulation of cAMP levels. Arch. Insect Biochem. Physiol. 55:178–187, 2004. © 2004 Wiley‐Liss, Inc.
Expression and localization of the Spodoptera frugiperda allatotropin (Spofr‐AT) and allatostatin (Spofr‐AS) genes
Authors: Abdel‐latief Mohatmed , Meyering‐Vos Martina , Hoffmann Klaus H. 
Published: March 2004

AbstractManduca sexta allatotropin and allatostatin were the first corpora allata (CA) regulating neuropeptides identified from Lepidoptera. Recently, we cloned the allatotropin (Spofr‐AT) and the allatostatin (Spofr‐AS) genes from the fall armyworm Spodoptera frugiperda. Using one‐step RT‐PCR for semi‐quantification of the gene expression, we now demonstrate that three mRNA isoforms of the Spofr‐AT gene and the Spofr‐AS gene are expressed in brain, digestive tract, and reproductive organs of larvae, pupae, and adults in a time‐ and tissue‐specific manner. Expression rates in the brain and in various parts of the digestive tract prove the dual role of the peptides as brain/gut (neuro)peptides. The functional meaning of ovarian and testes expression of the genes is not yet clear, although myoregulatory properties of the peptides are probable. The tissue‐specific localization of the prohormone expression, as demonstrated by whole mount in situ hybridization, confirms the overall distribution of the prohormones as shown by RT‐PCR and supports the pleiotropic functions of the peptides. Arch. Insect Biochem. Physiol. 55:188–199, 2004. © 2004 Wiley‐Liss, Inc.
Isolation, characterization, and recombinant expression of multiple serpins from the cat flea, Ctenocephalides felis
Authors: Brandt K.S. , Silver G.M. , Becher A.M. , Gaines P.J. , Maddux J.D. , Jarvis E.E. , Wisnewski N. 
Published: March 2004

AbstractSeveral clones encoding serine protease inhibitors were isolated from larval and adult flea cDNA expression libraries by immunoscreening and PCR amplification. Each cDNA contained an open reading frame encoding a protein of approximately 45 kDa, which had significant sequence similarity with the serpin family of serine protease inhibitors. The thirteen cDNA clones isolated to date encode serpin proteins, which share a primary structure that includes a nearly identical constant region of about 360 amino acids, followed by a C‐terminal variable region of about 40–60 amino acids. The variable C‐terminal sequences encode most of the reactive site loop (RSL) and are generated by mutually exclusive alternative exon splicing, which may confer unique protease selectivity to each serpin. Utilization of an alternative exon splicing mechanism has been verified by sequence analysis of a flea serpin genomic clone and adjacent genomic sequences. RNA expression patterns of the cloned genes have been examined by Northern blot analysis using variable region‐specific probes. Several putative serpins have been overexpressed using the cDNA clones in Escherichia coli and baculovirus expression systems. Two purified baculovirus‐expressed recombinant proteins have N‐terminal amino acid sequences identical to the respective purified native mature flea serpins indicating that appropriate N‐terminal processing occurred in the virus‐infected insect cells. Arch. Insect Biochem. Physiol. 55:200–214, 2004. © 2004 Wiley‐Liss, Inc.
Family study of fibromyalgia
Authors: Arnold Lesley M. , Hudson James I. , Hess Evelyn V. , Ware Avis E. , Fritz Deborah A. , Auchenbach Megan B. , Starck Linsey O. , Keck Paul E. 
Published: March 2004

AbstractObjectiveTo assess for familial aggregation of fibromyalgia (FM) and measures of tenderness and pain, and for familial coaggregation of FM and major mood disorder (major depressive disorder or bipolar disorder).MethodsProbands meeting the American College of Rheumatology criteria for FM and control probands with rheumatoid arthritis (RA) and no lifetime diagnosis of FM were recruited from consecutive referrals to 2 community‐based rheumatology practices. Probands were ages 40–55 years and had at least 1 first‐degree relative age 18 years or older who was available for interview and examination. All probands and interviewed relatives underwent a dolorimeter tender point examination and a structured clinical interview. Interviewed relatives were asked about first‐degree relatives who were not available for interview, using a structured family interview. Logistic and linear regression models, adjusting for the correlation of observation within families, were applied to study the aggregation and coaggregation effects.ResultsInformation was collected for 533 relatives of 78 probands with FM and 272 relatives of 40 probands with RA. FM aggregated strongly in families: the odds ratio (OR) measuring the odds of FM in a relative of a proband with FM versus the odds of FM in a relative of a proband with RA was 8.5 (95% confidence interval [95% CI] 2.8–26, P = 0.0002). The number of tender points was significantly higher, and the total myalgic score was significantly lower in the relatives of probands with FM compared with the relatives of probands with RA. FM coaggregated significantly with major mood disorder: the OR measuring the odds of major mood disorder in a relative of a proband with FM versus the odds of major mood disorder in a relative of a proband with RA was 1.8 (95% CI 1.1–2.9, P = 0.013).ConclusionFM and reduced pressure pain thresholds aggregate in families, and FM coaggregates with major mood disorder in families. These findings have important clinical and theoretical implications, including the possibility that genetic factors are involved in the etiology of FM and in pain sensitivity. In addition, mood disorders and FM may share some of these inherited factors.
Increased serum matrix metalloproteinase 9 levels in systemic lupus erythematosus patients with neuropsychiatric manifestations and brain magnetic resonance imaging abnormalities
Authors: Ainiala Hanna , Hietaharju Aki , Dastidar Prasun , Loukkola Jukka , Lehtimäki Terho , Peltola Jukka , Korpela Markku , Heinonen Tomi , Nikkari Seppo T. 
Published: March 2004

AbstractObjectiveTo evaluate whether serum matrix metalloproteinase 9 (MMP‐9) levels are associated with neuropsychiatric manifestations, particularly cognitive dysfunction, as evaluated by neuropsychological testing and brain magnetic resonance imaging (MRI) abnormalities in patients with systemic lupus erythematosus (SLE).MethodsMMP‐9 determinations were made in 44 patients with SLE and 43 healthy controls who underwent a clinical neurologic and neuropsychological investigation in order to identify neuropsychiatric manifestations. Cerebral MRI scans with volumetric estimation of intracranial cerebrospinal fluid spaces, T1‐weighted lesions, and T2‐weighted lesions were performed for all subjects. SLE activity was assessed by the European Consensus Lupus Activity Measure (ECLAM) index, and accumulated neuropsychiatric abnormality was assessed by the Systemic Lupus International Collaborating Clinics (SLICC)/American College of Rheumatology damage index.ResultsNo significant difference was found in serum MMP‐9 levels between the overall group of SLE patients and controls. However, SLE patients who had at least 1 neuropsychiatric manifestation (NPSLE patients) had significantly higher serum MMP‐9 concentrations than did SLE patients without neuropsychiatric syndromes (P = 0.009). Among patients with NPSLE, those with cognitive deficits had significantly higher concentrations of serum MMP‐9 than did those with normal cognitive function (P = 0.027). Furthermore, serum MMP‐9 levels had a significant positive correlation with the volumes of T1‐weighted and T2‐weighted lesions in the brain MRI (P = 0.031 and P = 0.015, respectively). The concentration of serum MMP‐9 correlated significantly with the SLICC index but not with the ECLAM index.ConclusionElevated levels of serum MMP‐9 in patients with SLE may reflect neuropsychiatric involvement, particularly cognitive dysfunction. The serum MMP‐9 concentration may be associated with small‐ vessel cerebral vasculopathy and increased risk of cerebral ischemic events in patients with SLE.
Use of multispectral magnetic resonance imaging analysis to quantify erosive changes in the hands of patients with rheumatoid arthritis: Short‐term and long‐term longitudinal studies
Authors: Ostrowitzki Susanne , Rédei János , Lynch John A. , Carano Richard A. D. , Zaim Souhil , Miaux Yves , Genant Harry K. 
Published: March 2004

AbstractObjectiveMagnetic resonance imaging (MRI) has been shown to be more sensitive than radiography for detecting bone erosions in rheumatoid arthritis (RA). Semiquantitative scoring based on visual image assessment has been introduced. However, there is considerable interest in true quantitative measures, particularly in the context of clinical trials designed to show differences between treatment groups. This study was undertaken to investigate the use of a new quantitative approach, multispectral (MS) image analysis, for assessing erosive change.MethodsT1‐weighted spin‐echo (SE) and fat‐suppressed gradient‐echo (GE) sequences of metacarpophalangeal joints of the dominant hand were acquired at various time points throughout a 2‐year period. MS analysis was applied to all images, resulting in segmentation into a generalized bone and a soft tissue class. Voxel changes from one to the other class identified apparent bone lesion volume change (ΔBLV). MR images were also visually scored for erosions (E score). All analyses were performed separately, on a per‐joint basis, for short‐term and long‐term data sets.ResultsAnalysis of variance with adjustment for individual effect revealed similar results in the short‐term and the long‐term studies, using either GE or SE images for visual assessment. Patients with an increase in E score on visual assessment had a significantly higher ΔBLV than those without.ConclusionTemporal MS analysis of MRIs can be used to detect and quantify erosive changes in RA. This semiautomated method may be useful for demonstrating differences between treatment groups in clinical trials.