bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrasonically initiated emulsion polymerization of methyl methacrylate
Authors: Liao Yongqin , Wang Qi , Xia Hesheng , Xu Xi , Baxter Steven M. , Slone Robert V. , Wu Shuguang , Swift Graham , Westmoreland David G. 
Published: August 2002

AbstractThe ultrasonically initiated emulsion polymerization of methyl methacrylate (MMA) was investigated. Experimental results show that sodium dodecyl sulfonate (SDS) surfactant plays a very important role in obtaining a high polymer yield, because in the absence of SDS, monomer conversion is near zero. Thus, the surfactant serves as an initiator and as interfacial modifier in this system (MMA/H2O), and the monomer conversion increases significantly with increasing SDS concentration. An increase in the reactor temperature also leads to an increase in the monomer conversion. An appropriate increase in the N2 purging rate also leads to higher conversion. The conversion of MMA decreases with increasing monomer concentration because of the higher viscosity of the system. With the experimental results, optimized reaction conditions were obtained. Accordingly, a high monomer conversion of about 67% and a high molecular weight of several millions can be obtained in a period of about 30 min. Furthermore, transmission electron micrographs show that the latex particles prepared are nanosized, indicating a promising technique for preparing nanoscale latex particles with a small amount of surfactant. In conclusion, a promising technique for ultrasonically initiated emulsion polymerization has been successfully performed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3356–3364, 2001
Synthesis of phosphate‐pendant polymers and their application to thermally latent polymeric initiators
Authors: Kim Moon Suk , Sanda Fumio , Endo Takeshi 
Published: August 2002

AbstractA novel phosphate monomer, O‐p‐(methacryloyloxymethyl)benzyl O,O‐diethyl phosphate (MDP) was synthesized by the reaction of diethyl phosphorochloridate with 1,4‐benzenedimethanol, followed by the reaction with methacryloyl chloride in the presence of triethylamine. The radical polymerization of MDP and copolymerization with methyl methacrylate were carried out in the presence of 2,2′‐azobisisobutyronitrile (3 mol %) in dimethylacetamide at 60 °C for 20 h to afford phosphate‐pendant polymers. The polymerization of glycidyl phenyl ether (GPE) was carried out with the phosphate‐pendant polymer as an initiator in the presence of ZnCl2. The polymerization did not proceed below 90 °C but rapidly proceeded above 90 °C to afford polyGPE. The phosphate‐pendant polymer served as a good thermally latent polymeric initiator. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3365–3370, 2001
Crystal‐structure dependence of electroactive properties in differently prepared poly(vinylidene fluoride/hexafluoropropylene) copolymer films
Authors: Jayasuriya Ambalangodage C. , Schirokauer Adriana , Scheinbeim Jerry I. 
Published: August 2002

AbstractThe electroactive properties of two random copolymers of vinylidene fluoride (VDF) and hexafluoropropylene (HFP) were studied. The compositions were 95/5 and 85/15 mol % P(VDF/HFP). For each composition, three different film‐preparation methods were used—solvent casting, melt‐pressed quenched, and melt‐pressed slow‐cooled. The ferroelectric properties observed were strongly dependent on the preparation methods of the films as well as the HFP molar content of the samples. The highest remanent polarizations (Pr) obtained from electric displacement versus electric field (D‐E) hysteresis data are 80 and 50 mC/m2 for the 5 and 15% HFP solvent‐cast samples, respectively. The slow‐cooled samples do not exhibit any ferroelectric behavior for either the 5 or 15% HFP copolymers. It was also observed that both the 5 and 15% HFP slow‐cooled samples have a smaller electrostrictive response relative to the other two types of samples. Wide‐angle X‐ray diffraction and DSC results suggest that the 5% HFP sample has a higher crystallinity relative to the 15% HFP sample for each preparation method. In addition, different crystal phases form in the samples resulting from the different preparation methods. Fourier transform infrared results suggest that the slow‐cooled samples are in the nonpolar α phase, whereas the quenched and solvent‐cast samples are more likely in the polar β phase. The slow‐cooled samples do not show a switching peak in their nonpolar α‐phase crystalline state. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2793–2799, 2001
Correlation of the elution behavior in temperature rising elution fractionation and melting in the solid‐state and in the presence of a diluent of polyethylene copolymers
Authors: Mirabella Francis M. 
Published: August 2002

AbstractCompositionally homogeneous poly(ethylene‐α‐olefin) random copolymers with 1‐butene and 1‐hexene comonomers have been studied. The melting of solution‐crystallized specimens of these copolymers in the presence of trichlorobenzene as a diluent with differential scanning calorimetry (DSC) is well correlated with analytical temperature rising elution fractionation (A‐TREF) elution temperature profiles. This indicates that the A‐TREF experiment is essentially a diluent melting experiment. Furthermore, the correction of the corresponding solid‐state melting endotherms of these copolymers with Flory's diluent melting equation yields curves that also correlate very well with the DSC diluent melting curves and the A‐TREF elution temperature profiles. Values of χ, the Flory–Huggins interaction parameter, are determined for these copolymers in trichlorobenzene. χ decreases as short‐chain branching increases. The A‐TREF elution temperature profiles of one of these copolymers are the same, within experimental error, for dilute‐solution crystallizations of the copolymer performed over an extremely broad time schedule (10 s to 3 days). This indicates the profound effect of the branches, as limiting points of the ethylene sequences, in controlling the crystal thickness distribution, which in turn controls the melting point in the presence of the diluent, or the elution temperature from the A‐TREF. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2819–2832, 2001
Simulation of phase‐separated structures of liquid‐crystalline polymer/flexible polymer blends
Authors: Yang Shenglin , Liang Borun 
Published: August 2002

AbstractThe phase‐separation kinetics of liquid‐crystalline polymer/flexible polymer blends was studied by the coupled time‐dependent Ginzberg–Landau equations for compositional order parameter ϕ and orientational order parameter Sij. The computer simulations of phase‐separated structures of the blends were performed by means of the cell dynamical system in two dimensions. The compositional ordering processes of phase separation are demonstrated by the time evolution of ϕ. The influence of orientational ordering on compositional ordering is discussed. The small‐angle light scattering patterns are numerically reproduced by means of the optical Fourier transformation of spatial variation of the polarizability tensor αij, and the azimuthal dependence of the scattering intensity distribution is interpreted. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2915–2921, 2001
Effect of the copolymer composition on the K and a constants of the Mark–Houwink equation: Styrene–methyl methacrylate random copolymers
Authors: Songkhla P. Na , Wootthikanokkhan J. 
Published: August 2002

AbstractThis article reports a study of the effect of composition in styrene–methyl methacrylate random copolymers on K and a constants in the Mark–Houwink equation. Copolymers with a variety of compositions and chain lengths were prepared through a controlled free‐radical copolymerization, with benzyl diethyldithiocarbamate and tetraethyl thiuram disulfide as iniferters. The synthesized products were analyzed with several techniques, including Fourier transform infrared, 1H NMR, gel permeation chromatography, and viscometry. By relating the determined constants K and a of various copolymers to their composition, we found that the constant varied nonlinearly with the composition. The constant a decreased with increasing poly(methyl methacrylate) (PMMA) content in the copolymer molecule up to 60 wt %. After that, the constant increased with the PMMA content, reaching the value of the PMMA homopolymer. However, the constant K initially increased with the PMMA content up to a critical composition (60 wt %) and subsequently decreased with further increasing PMMA content. These results suggest that the molecular weight of a polystyrene–PMMA random copolymer of known composition cannot be approximated with a simple linear equation comprising the K and a values of each relevant homopolymers. The aforementioned trends are qualitatively discussed in relation to some possible sequential distribution in the copolymer molecules and the resulting conformation. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 562–571, 2002; DOI 10.1002/polb.10119
Long‐term growth of core‐set curl in poly(ethylene terephthalate) film
Authors: Greener J. , Gillmor J. R. 
Published: August 2002

AbstractSolid polymeric films (plates) commonly exhibit only partial recovery after being subjected to a bending moment for some finite duration. This phenomenon, generally called bending recovery or core‐set, has been described and successfully modeled in past studies using the viscoelastic plate bending theory. In this study, the viscoelastic theory of core‐set curl was extended to account for physical aging effects during the bending recovery test. The contribution of physical aging was incorporated into the model through the effective time theory and assuming a thermorheologically simple behavior. The model was tested against long‐term core‐set data for a biaxially oriented poly(ethylene terephthalate) (PET) film under ambient conditions and was then used to map the effect of sample age on the evolution of core‐set curl over long times. The predictions of the model agreed favorably with the data, and the results underscored the strong retarding effect of physical aging on the rate of acquisition of core‐set curl in PET film at ambient temperature. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1957–1967, 2001
Participation of oncological outpatients in psychosocial support
Authors: Plass Angela , Koch Uwe 
Published: August 2002

AbstractIn total, 132 cancer patients in four oncology outpatient clinics in Hamburg completed a questionnaire consisting of a newly designed instrument for measuring psychosocial support. In this questionnaire, patients were asked about their knowledge of institutions offering support, their previous participation in psychosocial support, the reasons for participation and their experience with and attitude towards it. A second section consisted of standardized instruments: the EORTC QLQ‐C30 questionnaire (Aaronson), the Brief Symptom Inventory (Derogatis and Melisaratos), the List of Physical Complaints (von Zerssen and Koller) and the Impact of Event Scale (Horowitz). Descriptive and variance‐analytical methods were used for the analysis of results. Most respondents were women (88%). The largest group (72%) had a history of breast cancer. A total of 28% of the patients in the sample had participated in psychosocial support, about 4% of these in self‐help groups. Participants in psychosocial support did not differ from non‐participants in gender, but they were significantly younger. They showed considerably higher scores in emotional and physical distress than non‐participants, their attitude towards psychosocial support was more positive, and they had more knowledge about institutions offering support than non‐participants. The main reasons listed for their participation in psychosocial support were mental distress, a desire to obtain help, and the wish to cope with the illness. The main reason for not participating was sufficient support from the family, friends or doctors. Copyright © 2001 John Wiley & Sons, Ltd.
Inspiratory flow reserve in boys with Duchenne muscular dystrophy
Authors: De Bruin Pedro F. , Ueki Jun , Bush Andrew , Y. Manzur Adnan , Watson Ann , Pride Neil B. 
Published: August 2002

AbstractPatients with advanced muscular dystrophy frequently develop ventilatory failure. Currently respiratory impairment usually is assessed by measuring vital capacity and the mouth pressure generated during a maximal inspiratory maneuver (PI,max), neither of which directly measures ventilatory capacity. We assessed inspiratory flow reserve in 26 boys [mean (SD) age 12.8 (3.8) years] with Duchenne muscular dystrophy (DMD) without ventilatory failure and in 28 normal boys [mean (SD) age 12.6 (1.9) years] by analyzing the ratio between the largest inspiratory flow during tidal breathing (V′I,max(t)) and during a forced vital capacity maneuver (V′I,max(FVC)), (V′I,max(t)/V′I,max(FVC)). We have compared this ratio with the forced vital capacity (FVC) and PI,max measured at functional residual capacity.Mean PI,max was −90(30)cmH2O, average 112% (range 57–179%) of predicted values in control boys and −31(11)cmH2O, average 40% predicted values in DMD boys (control vs DMD, P < 0.001). FVC was reduced in DMD boys [59(20)% predicted values vs 86(10)% predicted values in controls, P < 0.01]. Absolute V′I,max(FVC) was strongly related to FVC in both control and DMD boys; V′I,max(FVC) (expressed as FVC · s−1) was not related to PI,max in either group. The mean V′I,max(t)/V′I,max(FVC) ratio was higher in DMD 0.22 (0.08) than in controls 0.12 (0.03) (P < 0.001) indicating a reduction in inspiratory flow reserve in DMD. Inspiratory flow reserve was within the normal range in 8 of 19 DMD patients with PI,max less than 50% of predicted values.We conclude that measurement of inspiratory flow reserve (V′I,max(t)/V′I,max(FVC) ratio) provides a simple and direct assessment of dynamic inspiratory muscle function which is not replicated by static measurement of PI,max or vital capacity and might be useful in assessment of respiratory impairment in boys with Duchenne muscular dystrophy. Follow‐up studies are required to establish whether measures of inspiratory flow reserve are of clinical value in predicting subsequent ventilatory failure. Pediatr Pulmonol. 2001; 31:451–457. © 2001 Wiley‐Liss, Inc.
M13 endopeptidases: New conserved motifs correlated with structure, and simultaneous phylogenetic occurrence of PHEX and the bony fish
Authors: Bianchetti Laurent , Oudet Claudine , Poch Olivier 
Published: August 2002

AbstractM13 endopeptidase alignments have focused mainly on mammalian sequences and on the active site region defining the catalytic sequence signatures. Aligning all available M13 from bacteria to human on a full‐length basis, we have performed a sequence analysis. This enabled us to highlight the origin and function of the M13 PHEX subtype family endopeptidase (phosphate regulating gene with homologies to endopeptidases on the X chromosome). New evolutionary conserved regions in both prokaryotes and eukaryotes have been detected and eukaryotic‐specific regions clearly delineated. Using the recently solved neprilysin structure, we have observed that all new motifs, except one, localize in the spatial vicinity of the previously reported catalytic signatures. Interestingly, a highly hydrophobic pocket containing three newly reported motifs is centered by the C‐terminal tryptophan residue. Extensive M13 searches in complete and in progress higher eukaryotic genomes have lead to the identification of Danio rerio as the simplest organism having PHEX. Finally, the human PHEX substrate, the parathyroid hormone‐related peptide, PTHrP107–139, is absent in bony fish: this suggests the existence of further PHEX substrates common to both bony fishes and higher vertebrates. Proteins 2002;47:481–488. © 2002 Wiley‐Liss, Inc.
Organoclays for controlled release of the herbicide fenuron
Authors: Hermosin M Carmen , Calderón M Jesús , Aguer Jean‐Pierre , Cornejo Juan 
Published: August 2002

AbstractOrganoclays were assayed as matrices in which to associate herbicides, with the aim of decreasing product losses that could give rise to water contamination from agricultural activities. Fenuron was selected as model of a very mobile and highly water‐soluble herbicide. Two different organoclays of high (A‐HDT) and low (H‐C18) reversible fenuron sorption were selected. Herbicide–organoclay complexes were prepared from the two organoclays and with two different fenuron contents (20 and 40 g AI kg−1) and two different mixing times, so as to form a series of weak and strong complexes. The release of fenuron from those complexes into water and water/soil suspensions gave values of T50 (time to release 50% of the fenuron content) ranging from 0.3 min to 2400 h. The total fenuron released in these closed systems ranged from 48 to 80% of the fenuron in the complex. The organoclay type (high or low sorptivity) had the greatest influence on fenuron release, followed by the strong or weak complex, suggesting that herbicide–organoclay interactions are the main factors controlling release. Soil column leaching experiments showed fenuron–organoclay complexes to be effective in reducing the peak herbicide concentration in the leachate to a half (6 µM) or a quarter (3 µM) of that obtained from the free technical compound (12 µM). Herbicide lost through leaching was reduced from 78% for the free technical fenuron to 50–30%, depending on the organoclay used as carrier and the strength of the complex. Bioassay with ryegrass showed that the weak fenuron/H‐C18 complex (40 g AI kg−1) gave the same herbicidal activity as technical fenuron. The potential suitability of low‐sorptive organoclays for conferring slow‐release properties on the fenuron complex has been demonstrated.© 2001 Society of Chemical Industry
Herbicide sensitivity of transgenic multiple herbicide‐tolerant oilseed rape
Authors: Senior Ian J , Moyes Catherine , Dale Philip J 
Published: August 2002

AbstractGlyphosate and glufosinate‐ammonium herbicide tolerance traits were combined into both winter and spring lines of Brassica napus L. This allowed the study of possible interactions between these transgenes in two genetic backgrounds when treated with a variety of herbicides. Selective herbicides that are commonly used within Brassica crops showed no adverse effects on the transgenic plants or their null controls. Lines containing both glyphosate and glufosinate transgenes remained tolerant to their respective herbicides, regardless of the presence of the second tolerance transgene. Lines containing only a single transgene retained tolerance to the encoded trait and did not show cross‐tolerance to the second. Null lines were killed by either herbicide. All plant lines, regardless of their transgene content, were found to be equally susceptible to three herbicides (paraquat, metsulfuron‐methyl and mecoprop), commonly used to remove volunteer B napus from succeeding crops and set‐a‐side land.© 2002 Society of Chemical Industry
Improved preparation of amyloid‐β peptides using DBU as Nα‐Fmoc deprotection reagent
Authors: Tickler Anna K , Barrow Colin J , Wade John D 
Published: August 2002

AbstractPrevious studies have shown the amyloid peptides, Aβ 1‐40/42, to be exceptionally difficult to assemble by Fmoc‐solid phase peptide synthesis due to the high hydrophobicity of the C‐terminal segment and resulting on‐resin aggregation. We found that the use of the stronger and more efficient base, DBU, at a concentration of 2% in DMF for Nα‐Fmoc deprotection allowed substantially improved continuous flow solid phase assembly of the model peptide Aβ 29‐40/42 fragments. This suggested that, at least for these sequences, incomplete deprotection was a greater problem than incomplete amino acid acylation. This base was then used during the synthesis of both Aβ 1‐40 and Aβ 1‐42, up to and including Ser8, from which point 20% piperidine in DMF was utilized so as to avoid potential aspartimide formation at Asp7. By this means, the deprotection efficiency through the difficult C‐terminal portion of the sequence was much improved and resulted in increased availability of terminal amino groups for acylation. This simple strategy that obviates the need for special conditions significantly improved crude peptide quality and allowed considerable facilitation of subsequent purification. Copyright © 2001 European Peptide Society and John Wiley & Sons, Ltd.
Recent insights into body weight control: From physiology to pathology
Authors: Krysiak Robert , Okopień Bogusław , Belowski Dariusz , Madej Andrzej , Herman Zbigniew Stanisław 
Published: August 2002

AbstractOver the past several years, new modulators of feeding and body weight have been discovered, and our knowledge of the mechanisms and neurohumoral interactions between anorexigenic and orexigenic compounds has increased dramatically. This review aims to summarize the present knowledge of the role of leptin and several hypothalamic neuropeptides, such as neuropeptide Y (NPY), corticotropin‐releasing hormone (CRH) and melanocortins, in the regulation of appetite and body weight. It also presents the progress made in the design of interactions between leptin and hypothalamic peptides in the regulation of feeding. The role of these compounds in the pathogenesis of obesity in animals and humans, and their potential usefulness in the treatment of this disorder, are discussed. Copyright © 2000 European Peptide Society and John Wiley & Sons, Ltd.
Inhibition of P. falciparum by steroids isolated from Solanum nudum
Authors: Pabón Adriana , Carmona Jaime , Maestre Amanda , Camargo Mauricio , Blair Silvia 
Published: August 2002

AbstractResistance to antimalarials has been widely reported and constitutes a major problem around the world. In Colombia, resistance of P. falciparum to chloroquine has been reported as 47%–97%, to amodiaquine 3%–7% and to sulfadoxine‐pyrimethamine as 9%–13%. The search for new antimalarials is a priority and with this aim we studied the in vitro antimalarial activity of plants used by traditional healers.
Incorporation of 3H‐hypoxanthine by the strain FCB‐2 of P. falciparum was used to measure the degree of inhibition produced by the steroids SN‐1 tumacone A (C29H44O5), SN‐2 tumacone B (C27H42O4), SN‐3 tumacoside A (C35H54O10), and SN‐4 tumacoside B (C33H52O9). All compounds were obtained from the dried stems and leaves of Solanum nudum. The mean growth inhibition of P. falciparum was 71%, 56%, 21% and 12% with each of the compounds SN‐1, SN‐2, SN‐3 and SN‐4. These results constitute an important discovery since they may account for the antimalarial properties of extracts of Solanum nudum by a sensitive method. Future work should include study of the in vivo anti‐malarial effect of these extracts. Copyright © 2002 John Wiley & Sons, Ltd.