bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxygen‐barrier properties of cold‐drawn polyesters
Authors: Liu R. Y. F. , Schiraldi D. A. , Hiltner A. , Baer E. 
Published: August 2002

AbstractThe improvement of oxygen‐barrier properties of glassy polyesters by orientation was examined. Poly(ethylene terephthalate) (PET), poly(ethylene naphthalate), and a copolymer based on PET in which 55 mol % of the terephthalate was replaced with bibenzoate (PET‐BB55) were oriented by constrained uniaxial stretching. In a fairly narrow window of stretching conditions near the glass‐transition temperature, it was possible to achieve uniform extension of the polyesters without crystallization or stress whitening. The processes of orientation and densification correlated with the conformational transformation of glycol linkages from gauche to trans. Oxygen permeability, diffusivity, and solubility decreased with the amount of orientation. A linear relationship between the oxygen solubility and polymer specific volume suggested that the cold‐drawn polyester could be regarded as a one‐phase densified glass. This allowed an analysis of oxygen solubility in accordance with free‐volume concepts of gas permeability in glassy polymers. Orientation was seen as the process of decreasing the amount of excess‐hole free volume and bringing the nonequilibrium polymer glass closer to the equilibrium (zero‐solubility) condition. Cold drawing most effectively reduced the free volume of PET‐BB55. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 862–877, 2002
Specific interactions and phase behavior of ternary poly(2‐vinylpyridine)/poly(N‐vinyl‐2‐pyrrolidone)/bisphenol A blends
Authors: Li Xue‐Dong , Goh S. H. 
Published: August 2002

AbstractHydrogen‐bonding interactions between bisphenol A (BPA) and two proton‐accepting polymers, poly(2‐vinylpyridine) (P2VPy) and poly(N‐vinyl‐2‐pyrrolidone) (PVP), were examined by Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). The Flory–Huggins interaction‐energy densities of BPA/P2VPy and BPA/PVP blends were determined by the melting point depression method. The interaction parameters for both BPA/P2VPy and BPA/PVP blend systems were negative, demonstrating the miscibility of BPA with P2VPy as well as PVP. The miscibility of ternary BPA/P2VPy/PVP blends was examined by DSC, optical observation, and solid‐state nuclear magnetic resonance spectroscopy. The experimental phase behavior of the ternary blend system agreed with the spinodal phase‐separation boundary calculated using the determined interaction‐energy densities. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1125–1134, 2002
Diffusion mobility of reactants, phase equilibrium, and specific features of radical copolymerization kinetics in the nonyl acrylate/2‐methyl‐5‐vinyltetrazole system
Authors: Mikhailov Yu. M. , Ganina L. V. , Kurmaz S. V. , Smirnov V. S. , Roshchupkin V. P. 
Published: August 2002

AbstractCombined analysis of experimental data on monomer diffusion, phase equilibrium, and copolymerization kinetics in systems of monomers (nonyl acrylate and 2‐methyl‐5‐vinyltetrazole) as well as their copolymers and homopolymers was carried out. The composition of the mixture in the vicinity of the growing macroradical can differ significantly from the average composition in the whole reactor volume because of consumption of the more‐reactive reactant 2‐methyl‐5‐vinyltetrazole. Nonyl acrylate exhibited limited compatibility with copolymers enriched in 2‐methyl‐5‐vinyltetrazole and its homopolymer. Phase diagrams were obtained for the latter homopolymer. The concentration plots of the diffusion coefficients of both monomers in their copolymers of various compositions were determined. Microphase separation was observed at specific conversions in the reaction system where the composition of a copolymer and its concentration in a monomer solution approached the binodal of the phase diagram. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1383–1389, 2002
Hydrophobicity of fluoro‐containing physical crosslinkage domains in hydrophobically modified poly(acrylic acid) gels
Authors: Tian Qin , Zhao Xian , Tang Xiaozhen , Zhang Yunxiang 
Published: August 2002

AbstractA series of hydrophobically modified poly(acrylic acid) gels were prepared by the radical copolymerization of acrylic acid and small amounts of hydrophobic comonomers, 2‐(N‐ethylperfluorooctane‐sulfoamido)ethyl methacrylate and lauryl acrylate, in tert‐butanol. The effects of the fractions and species of hydrophobes on hydrophobic association were determined. The hydrophobic association within the hydrophobically modified gels was proven with measurements of swelling and fluorescence as well as Fourier transform infrared spectroscopy. Fluorocarbon‐modified hydrogels showed stronger hydrophobicity than hydrocarbon‐modified hydrogels. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1236–1244, 2002
Thermal shrinkage stress in high‐speed‐spun, high molecular weight poly(ethylene terephthalate) filaments
Authors: Lim Jung Yul , Kim Sang Yong 
Published: August 2002

AbstractHigh‐speed spinning of poly(ethylene terephthalate) with an intrinsic viscosity of 0.98 dL/g was performed at a take‐up velocity of 2.5–5.5 km/min, and the effects of the fiber structure on the isothermal and nonisothermal shrinkage‐stress evolution in as‐spun filaments were investigated. In isothermal measurements, the peak shrinkage stress was consistent with the degree of amorphous orientation, whereas the so‐called frozen stress relaxation was rather constant with respect to the take‐up velocity. The maximum shrinkage stress in nonisothermal testing was also consistent with an amorphous orientation. A spontaneous elongation phenomenon took place for filaments spun at 2.5 and 3 km/min that resulted in the lowering of shrinkage stresses in both experiments. A simple calculation showed that the inertial force in the spin line was about half of the resultant shrinkage force. Filaments spun at 5.5 km/min had markedly lower shrinkage stresses and shrinkage with respect to the degree of amorphous orientation. This was attributed to the fiber structure, which gave a much lower loss‐tangent maximum for these filaments. In addition, a hypothetical model is proposed suggesting the possibility that filaments spun at 5.5 km/min may have narrow tie‐chain‐length distributions that provide relatively longer shortest tie molecules. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 964–972, 2001
Surgical experience in patients with cystic fibrosis: A 25‐year perspective
Authors: Saltzman Daniel A. , Johnson Eric M. , Feltis Brad A. , Wilienski Catherine , Warwick Warren J. , Leonard Arnold S. 
Published: August 2002

AbstractThe spectrum of surgical diseases in patients with cystic fibrosis (CF) has not been comprehensively studied. A retrospective review of 792 consecutive patients with CF presenting over a 25 year period (1970–1994) was made to determine the incidence of operations, procedures performed, complications encountered, and impact on physical development and pumonary function tests (PFTs).A total of 191 operations were performed on 130 (16%) of the 792 patients; 98 operations (51%) were abdominal, 58 (30%) thoracic, and 31 (16%) hernias; 64 were male, and 66 female; average age was 14 ± 10 years. Complications occurred in 12 (16%); 9 deaths were from progressive respiratory failure, 2 from superficial wound infections, and 1 from an episode of line sepsis. In the first 15 years, 9 complications occurred in 126 operations vs. 3 in 73 operations during the last 10 years. Operations were classified as emergent, urgent, or elective. Of the 9 deaths, 8 occurred after emergent or urgent operations (4 abdominal and 4 thoracic), while 1 death occured following elective herniorrhaphy. For each subgroup, (abdominal, thoracic, and hernia), there was no difference in height/weight indicies, peak flow, forced vital capacity (FVC), forced expired volume in 1 sec (FEV1), or FEV1/FVC ratio when comparing 1 year preoperation and 1 year postoperation.In conclusion, patients in this high‐risk population were operated on with few complications, but when a complication occured it tended to be pulmonary and fatal (4.7% of all operations). Furthermore, operations did not cause significant deteriorations in PFTs and they did not cause these children to fall off their expected age‐adjusted growth curves. Pediatr Pulmonol. 2002; 33:106–110. © 2002 Wiley‐Liss, Inc.
Transition programs in cystic fibrosis centers: Perceptions of patients
Authors: Anderson Deborah L. , Flume Patrick A. , Hardy Kristina K. , Gray Sue 
Published: August 2002

AbstractThere is a growing population of adults with cystic fibrosis (CF) and a need for development of adult CF programs. Recommendations for transfer of patients from pediatric care to an adult program include a transition program. The purpose of this study was to survey adult CF patients to assess their own concerns regarding this issue.A survey was sent to all 1,288 members of the International Association of Cystic Fibrosis Adults (IACFA), with a response rate of 25.9% (n = 334). The majority of patients (81.2%) received care from a CF center; the major difference between those seen at a CF center and those seen at another facility was proximity to a CF center. Nearly one‐fourth of patients seen at a CF center continued to receive care from a pediatrician even though a CF‐trained internist was available; though these patients were younger, their mean age was still about 30 years. Patients seen by a pediatrician were more like to be students and to live with their parents. Those patients seen in an adult program described a variety of criteria for their transfer to the adult pro‐gram, but there were no consistent findings to suggest a standard transition program. Indeed, many patients did not meet the adult team until the time of the transfer. Most importantly, the patients reported their level of concern about transfer as minimal, far less than what CF physicians had perceived.These differences may impede the successful transition of patients into an adult program. Pediatr Pulmonol. 2002; 33:327–331. © 2002 Wiley‐Liss, Inc.
Alignments grow, secondary structure prediction improves
Authors: Przybylski Dariusz , Rost Burkhard 
Published: August 2002

AbstractUsing information from sequence alignments significantly improves protein secondary structure prediction. Typically, more divergent profiles yield better predictions. Recently, various groups have shown that accuracy can be improved significantly by using PSI‐BLAST profiles to develop new prediction methods. Here, we focused on the influences of various alignment strategies on two 8‐year‐old PHD methods. The following results stood out. (i) PHD using pairwise alignments predicts about 72% of all residues correctly in one of the three states: helix, strand, and other. Using larger databases and PSI‐BLAST raised accuracy to 75%. (ii) More than 60% of the improvement originated from the growth of current sequence databases; about 20% resulted from detailed changes in the alignment procedure (substitution matrix, thresholds, and gap penalties). Another 20% of the improvement resulted from carefully using iterated PSI‐BLAST searches. (iii) It is of interest that we failed to improve prediction accuracy further when attempting to refine the alignment by dynamic programming (MaxHom and ClustalW). (iv) Improvement through family growth appears to saturate at some point. However, most families have not reached this saturation. Hence, we anticipate that prediction accuracy will continue to rise with database growth. Proteins 2002;46:197–205. © 2001 Wiley‐Liss, Inc.
3′,5′‐Cyclic nucleotide phosphodiesterases class III: Members, structure, and catalytic mechanism
Authors: Richter Wito 
Published: August 2002

Abstract3′,5′‐Cyclic nucleotide phosphodiesterases (PDEs) comprise a superfamily of enzymes that were previously divided by their primary structure into two major classes: PDE class I and II. The 3′,5′‐cyclic AMP phosphodiesterase from Escherichia coli encoded by the cpdA gene does not show any homology to either PDE class I or class II enzymes and, therefore, represents a new, third class of PDEs. Previously, information about essential structural elements, substrate and cofactor binding sites, and the mechanism of catalysis was unknown for this enzyme. The present study shows by computational analysis that the enzyme encoded by the E. coli cpdA gene belongs to a family of phosphodiesterases that closely resembles the catalytic machinery known from purple acid phosphatases and several other dimetallophosphoesterases. They share both the conserved sequence motif, D‐(X)n‐GD‐(X)n‐GNH[E/D]‐(X)n‐H‐(X)n‐GHXH, which contains the invariant residues forming the active site of purple acid phosphatases, a binuclear Fe3+‐Me2+‐containing center, as well as a βαβαβ motif as a typical secondary structure signature. Furthermore, the known biochemical properties of the bacterial phosphodiesterase encoded by the cpdA gene, such as the requirement of iron ions and a reductant for maintaining its catalytic activity, support this hypothesis developed by computational analysis. In addition, the availability of atomic coordinates for several purple acid phosphatases and related proteins allowed the generation of a three‐dimensional model for class III cyclic nucleotide phosphodiesterases. Proteins 2002;46:278–286. © 2002 Wiley‐Liss, Inc.
Enzymatic circularization of a malto‐octaose linear chain studied by stochastic reaction path calculations on cyclodextrin glycosyltransferase
Authors: Uitdehaag Joost C.M. , van der Veen Bart A. , Dijkhuizen Lubbert , Elber Ron , Dijkstra Bauke W. 
Published: August 2002

AbstractCyclodextrin glycosyltransferase (CGTase) is an enzyme belonging to the α‐amylase family that forms cyclodextrins (circularly linked oligosaccharides) from starch. X‐ray work has indicated that this cyclization reaction of CGTase involves a 23‐Å movement of the nonreducing end of a linear malto‐oligosaccharide from a remote binding position into the enzyme acceptor site. We have studied the dynamics of this sugar chain circularization through reaction path calculations. We used the new method of the stochastic path, which is based on path integral theory, to compute an approximate molecular dynamics trajectory of the large (75‐kDa) CGTase from Bacillus circulans strain 251 on a millisecond time scale. The result was checked for consistency with site‐directed mutagenesis data. The combined data show how aromatic residues and a hydrophobic cavity at the surface of CGTase actively catalyze the sugar chain movement. Therefore, by using approximate trajectories, reaction path calculations can give a unique insight into the dynamics of complex enzyme reactions. Proteins 2001;43:327–335. © 2001 Wiley‐Liss, Inc.
Finite dose diffusion studies: III. Effects of temperature, humidity and deposit manipulation on NAA penetration through isolated tomato fruit cuticles
Authors: Knoche Moritz , Bukovac Martin J 
Published: August 2002

AbstractEffects of temperature, humidity, rewetting and removal of deposits on penetration of NAA [2‐(1‐naphthyl)acetic acid] through isolated tomato (Lycopersicon esculentum Mill) fruit cuticles were studied using a finite dose diffusion system. In this system, an aqueous 5‐µl droplet (0.1 mM NAA in 20 mM citric acid buffer) is applied to the outer surface of a cuticle, which is mounted in a glass diffusion half‐cell. The cell wall surface is in contact with a receiver solution (20 mM citrate). Penetration is monitored by repeated sampling of the receiver solution. Droplets appeared dry on visual inspection within 1 h of application, but significant NAA penetration continued after droplet drying. Maximum rates of NAA penetration increased exponentially as temperature was increased (from 5 ° to 35 °C), the energy of activation averaging 153 (±11.6) kJ mol−1. At 35 °C, penetration reached a plateau within 10 h of application (at 91.1 (±1.0)% of dose applied) while at 5 °C penetration after 800 h reached only 30.2 (±7.5)%. Increasing relative humidity from 20 to 80% increased maximum rates [from 1.0 (±0.21) to 2.7 (±0.80)% h−1] and penetration at 120 h after application [from 36.8 (±2.1) to 64.3 (±3.7)%]. Rewetting deposits at 120, 240 and 360 h after application resulted in increased NAA penetration. However, amounts and rates of NAA penetration progressively decreased with each subsequent rewetting. Removal of deposits by cellulose acetate stripping at various times after droplet application resulted in a rapid decrease in NAA penetration. NAA penetration following deposit removal was always less than 6.1% of the amount of NAA applied and averaged 0.5 (±0.2)% when deposits were removed immediately after droplet drying.© 2001 Society of Chemical Industry
Biological properties of the novel fungicide cyazofamid against Phytophthora infestans on tomato and Pseudoperonospora cubensis on cucumber
Authors: Mitani Shigeru , Araki Satoshi , Yamaguchi Tomona , Takii Yasuko , Ohshima Takeshi , Matsuo Norifusa 
Published: August 2002

AbstractCyazofamid (ISO proposed common name), 4‐chloro‐2‐cyano‐N,N‐dimethyl‐5‐p‐tolylimidazole‐1‐sulfonamide is a novel fungicide exhibiting specific activity against diseases caused by Oomycetes. In tests, cyazofamid at 0.4–1.6 mg litre−1 exhibited excellent preventative activity against Phytophthora infestans on tomato and Pseudoperonospora cubensis on cucumber. Minimum inhibitory concentrations of cyazofamid against both diseases were over 63 times lower than those of mancozeb and at least 16 times lower than those of metalaxyl. Cyazofamid at 1.6–25 mg litre−1 exhibited not only preventative activity, but also stable residual activity and rainfastness. Cyazofamid at 6.3 mg litre−1 reduced zoosporangia formation of P infestans and P cubensis on host plants by 100 and 94% respectively. Cyazofamid also exhibited translaminar and curative activity. Cyazofamid has a new mode of action for fungicides and exhibits no cross‐resistance with other currently registered and commonly used fungicides. These properties lead to a high level control by cyazofamid in field.© 2001 Society of Chemical Industry
The relative toxicities of insecticides to earthworms of the Pheretima group (Oligochaeta)
Authors: Mostert Magdel A , Schoeman At S , Merwe Mac van der 
Published: August 2002

AbstractAn artificial soil test was used to determine the LC50values of carbaryl, chlorpyrifos, imidacloprid, cyfluthrin and fipronil against earthworms of the Pheretima group. For a 24‐h interval, carbaryl was the most toxic to earthworms (LC50 = 77 mg kg−1), followed by imidacloprid (155 mg kg−1), cyfluthrin (351 mg kg−1), chlorpyrifos (390 mg kg−1) and fipronil (>8550 mg kg−1) as the least toxic. For the 48‐h and 7‐day intervals, imidacloprid was the most toxic to earthworms (LC50 = 5 mg kg−1and 3 mg kg−1respectively), followed by carbaryl (16 mg kg−1; 9 mg kg−1), cyfluthrin (128 mg kg−1; 110 mg kg−1), chlorpyrifos (330 mg kg−1; 180 mg kg−1) and the least toxic was fipronil (>8550 mg kg−1both intervals). The surface application rates required to achieve these values are compared with the rates recommended for the control of turfgrass pests.© 2002 Society of Chemical Industry
Brain neurotransmitter receptor binding and nootropic studies on Indian Hypericum perforatum Linn.
Authors: Kumar Vikas , Khanna V. K. , Seth P. K. , Singh P. N. , Bhattacharya S. K. 
Published: August 2002

AbstractThe high affinity binding sites for serotonin and benzodiazepine in the frontal cortex, for dopamine in the striatum and muscarinic cholinergic receptors in the hippocampus were investigated in the brains of Charles Foster rats treated for 3 days. Transfer latency on elevated plus maze (TL), passive and active avoidance behaviour (PA and AA) and electroconvulsive shock (ECS) induced amnesia were also studied. Pilot studies indicated that single dose administration of Indian Hypericum perforatum (IHp) had little or no acute behavioural effects and hence the extract of IHp was administered orally at two dose levels (100 and 200 mg/kg, p.o.) once daily for 3 consecutive days, while piracetam (500 mg/kg, i.p.), a clinically used nootropic agent, was administered acutely to rats as the standard nootropic agent. Control rats were treated with an equal volume of vehicle (0.3% carboxymethyl cellulose). The results indicate that IHp treatment caused a significant decrease in the binding of [3H] spiroperone (DA‐D2 receptor) to the striatum and an increase in the binding of [3H] ketanserin (5‐HT2A receptor) and [3H] flunitrazepam (BDZ receptor) to the frontal cortex in rats. Preliminary pharmacological studies with IHp extract indicate the presence of two major behavioural actions, namely, antidepressant and anxiolytic. The present findings tend to elucidate the mechanism of earlier observations, the downregulation of the dopamine D2 receptor being consonant with anxiolytic and the upregulation of 5‐HT2A and BDZ receptors being consonant with antidepressant activity. Piracetam when given alone, shortened the TL on days 1, 2 and 9 day and also antagonized the amnesic effects of ECS on the TL significantly, whereas IHp antagonized the amnesia produced by ECS. IHp had no significant effect per se on the retention of the PA in rats but produced a significant reversal of ECS induced PA retention deficit. Piracetam showed a significant facilitatory effect per se on PA retention and also reversed the ECS induced impaired PA retention. In the AA test, piracetam facilitated the acquisition and retention of AA in rats but IHp had no effect per se. Both the doses of IHp and piracetam significantly attenuated the ECS induced impaired retention of AA. These results indicate a possible nootropic action of IHp in amnesic animals, which was comparable qualitatively to piracetam. Copyright © 2002 John Wiley & Sons, Ltd.
Rotundifuran, a labdane type diterpene from Vitex rotundifolia, induces apoptosis in human myeloid leukaemia cells
Authors: Ko W. G. , Kang T. H. , Lee S. J. , Kim Y. C. , Lee B. H. 
Published: August 2002

AbstractThe inhibitory effect of rotundifuran, a labdane type diterpene isolated from the fruit of Vitex rotundifolia, on the proliferation of human myeloid leukaemia HL‐60 cells was examined. The concentration required for 50% inhibition of the growth after 96 h was 22.5 µM. The mode of cell death induced by rotundifuran was found to be apoptosis, which was judged by the morphological alteration of the cells and by the detection of DNA fragmentation using agarose gel electrophoresis. The degree of apoptosis was quantified by a sandwich enzyme immunoassay and flowcytometric analysis. These results suggest that rotundifuran may be used as a potential chemopreventive and chemotherapeutic agent. Copyright © 2001 John Wiley & Sons, Ltd.