bluuebunny/crossref_metadata_2025_split huggingface dataset:
Degenerative spondylolisthesis in ancient and historic skeletons from New Mexico Pueblo sites
Authors: Merbs Charles F. 
Published: August 2002

AbstractThe objective of this study was to identify the presence of degenerative spondylolisthesis in adult Native American skeletons recovered from prehistoric and historic Pueblo sites in New Mexico. The vertebral columns of 491 individuals that were complete enough to allow the necessary observations produced 64 cases, with a total of 74 affected levels. The L5–S1 level was affected most frequently (78%), in contrast to clinical and anatomical studies where the L4–L5 level was usually affected (80%). Age and sex were found to be important factors, with the condition limited to middle and old adults, and occurring in females over males at a ratio of approximately 5:1. Olisthesis was shown to occur only in association with severe osteoarthritis of the zygapophysial joints, but severe osteoarthritis did not always result in olisthesis, particularly in males. Parallel or convergent inferior articular processes were found to increase in frequency in the presence of olisthesis, apparently resulting from degenerative remodeling that produced the olisthesis. The data also suggest that individuals with cranial border shifting in the column may be especially prone to olisthesis. Degenerative olisthesis was also observed in the cervical region. Am J Phys Anthropol 116:285–295, 2001. © 2001 Wiley‐Liss, Inc.
Ascorbic acid acts as a hydride donor towards ­2‐arsonocarboxylic acids
Authors: Ioannou Panayiotis V. , Siskos Michael G. 
Published: August 2002

Abstract2‐Arsonohexanoic acid is decomposed during its attempted reduction to 2‐arsenosohexanoic acid by triphenylphosphine in the presence of a catalytic amount of iodine. When ascorbic acid is substituted for the triphenylphosphine, ­hexanoic acid is obtained, implying that the arscorbic acid acts as a hydride donor. Copyright © 2001 John Wiley & Sons, Ltd.
Organotin levels in the Ria Formosa lagoon, Portugal
Authors: Coelho M. R. , Bebianno M. J. , Langston W. J. 
Published: August 2002

AbstractOrganotin concentrations were measured in water, sediments and clams (Ruditapes decussatus) from 11 sites in the Ria Formosa lagoon, Portugal, in 1992–93. Results showed a marked spatial pattern of tributyltin (TBT) and dibutyltin concentrations. The highest organotin concentrations were observed at Olhão (site 5), where the most important fishing harbour of the Southern coast of Portugal is located.Results indicated that fishing vessels, moored in the harbour at Olhão (site 5), were the major source of organotin contamination to the lagoon. No significant seasonal trend was observed, suggesting a continuous input of organotin compounds throughout the year. In several areas of the lagoon the TBT burdens in R. decussatus could have deleterious developmental effects. Copyright © 2002 John Wiley & Sons, Ltd.
Comparative study of polymer single cells based on sulfonated linear and star butadiene–styrene block copolymer electrolyte membranes
Authors: Mokrini A. , Acosta J. L. 
Published: August 2002

AbstractProton‐conducting electrolytes based on a sulfonated hydrogenated poly(butadiene–styrene) matrix were synthesized. Block copolymer ionomers were prepared through sulfonation of part of the styrene units. The free acid samples were characterized with X‐ray photoelectron spectroscopy to quantify sulfonation. Microstructural and electrical characterizations of membranes obtained from sulfonated polymer and blends were carried out with dynamic mechanical analysis, differential scanning calorimetry, and impedance spectroscopy. Electrolytes exhibiting the highest conductivities were tested in a model hydrogen/oxygen single fuel cell working at a medium temperature range (30–80°C) and at 1 bar of pressure. The current and power densities obtained were compared with commercial Nafion electrolyte. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 367–377, 2002
Quantitative determination of the distribution of free hydroxylic and carboxylic groups in unsaturated polyester and alkyd resins by 31P‐NMR spectroscopy
Authors: Spyros A. 
Published: August 2002

AbstractQuantitative 31P‐NMR spectroscopy is used to measure the hydroxyl and carboxyl content of some polyester resins (short‐ and long‐oil alkyds, polyols, polyesters) through derivatization of the —OH protons with 2‐chloro‐4,4,5,5‐tetramethyldioxaphospholane I. This methodology is shown to be superior to titration methods, since it can (a) discriminate between primary and secondary hydroxyl groups, (b) identify individual alcohols and acids present, (c) measure the amount of free fatty acids in oil‐modified alkyds, and (d) provide lower limits for the number‐averaged molecular weight of the resins and exact values for linear polyesters. A major advantage of the technique is that the NMR measurements are made on unmodified resins in their final product form supplied by the manufacturer. The information obtained is important for the characterization of the alkyd resins and affects drastically their physical properties and performance as products. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1635–1642, 2002
Phosphorous‐containing epoxy resins from a novel synthesis route
Authors: Liu Ying Ling 
Published: August 2002

AbstractThe P(O)‐H in 9,10‐dihydro‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) was used as an active group to react with the carbonyl group in 4,4′‐dihydroxybenzophenone (DHBP) to result a novel phosphorous‐containing biphenol compound (DOPO‐2OH). Phosphorous‐containing epoxy resins were therefore obtained from reacting DOPO‐2OH with epichlorohydrin or with diglycidylether bisphenol A. The synthesized compounds were characterized with FTIR, 1H and 31P NMR, elemental analysis, and epoxide equivalent weight titration to demonstrate the their chemical structures. Cured epoxy resins were prepared via thermal curing the epoxy resins with various curing agents. Thermal analysis results (differential scanning calorimetry and thermogravimetric analysis) revealed that these cured epoxy resins exhibited high glass transition temperatures and high thermal stability. High char yields at 700°C and high LOI (limited oxygen index) values were also found for the cured epoxy resins to imply that the resins were possessing high flame retardancy. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1697–1701, 2002
Studies of mechanical and moisture regain properties of methyl methacrylate grafted silk fibers
Authors: Maji Tarun Kumar , Basu Diya , Datta Chandan , Banerjee Amarnath 
Published: August 2002

AbstractThe mechanical properties such as the tenacity, breaking extension, initial modulus, elastic and work recovery, and stress relaxation behavior of methyl methacrylate (MMA) grafted silk fibers prepared under different conditions were measured and explained in terms of the relative dominance of the stress concentration, reduction in the interchain cohesion, and fiber matrix stiffening at different grafting percentages. The moisture regain characteristics of fibers grafted in the presence of different solvents were also studied and compared. The grafting of MMA on silk was found to improve the recovery properties significantly without affecting the stress relaxation behavior. The moisture regain studies indicate that moisture regain is reduced with increasing length of the grafted poly(MMA) chains. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 969–974, 2002; DOI 10.1002/app.10202
Kinetic investigations of acrylic–polyurethane composite latex
Authors: Kukanja Dolores , Golob Janvit , Krajnc Matjaž 
Published: August 2002

AbstractThe effect of various reaction parameters on the rate of polymerization, Rp, and on the particle size and morphology of aqueous acrylic–polyurethane hybrid dispersions, prepared by semibatch emulsion polymerization, was investigated. The particles of polyurethane dispersion were used as seeds during the polymerization of acrylic component: methyl methacrylate (MMA), butyl acrylate (BA), and a mixture of MMA and BA with the ratio of 1:1. These emulsions were found to form structured polymer particles in aqueous media using scanning electron microscopy. The kinetics of the emulsion polymerization was studied on the basis of Wessling's model. The influence of emulsifier and initiator concentrations, including the monomer feed rates, Rm, on the rates of polymerization and on the properties of the resulting dispersions were studied. The number of particles and the particle size were also measured during the polymerization process. The final values were found to be independent of the concentration of the emulsifier, initiator and the monomer feed rate in monomer starved conditions. In the steady‐state conditions, during the seeded semibatch hybrid emulsion polymerization, the rate of polymerization and the monomer feed rate followed the Wessling relationship 1/Rp = 1/K + 1/Rm. The dispersions MMA/PU, BA/PU, and MMA/BA/PU have K values of 0.0441, 0.0419 and 0.0436 mol/min, respectively. The seeded BA/PU hybrid polymerization proceeded according to Smith‐Ewart Case I kinetics, while the MMA/PU hybrid emulsions demonstrate Case II of the Smith‐Ewart kinetic model. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2639–2649, 2002
Synthesis and property of nanosized palladium catalysts protected by chitosan/silica
Authors: Huang Aiming , Liu Yinfeng , Chen Lai , Hua Jiadong 
Published: August 2002

AbstractA chitosan (CTN)/silica‐supported nanosized palladium catalyst was obtained from a silica‐supported chitosan palladium complex through a complex transition method. An adsorption model was employed to simplify the structure of the di‐supporter. It was indicated that when the polymer coil adsorbed on the silica surface with even a monolayer the catalytic activity would reach an optimum value, and different situations of the, nanosized palladium particles would cause a different catalysis. The molar ratio of the chitosan structure unit to the palladium would affect the metal's size, which therefore influenced its catalytic activity. The experimental results corresponded with the inferences. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 989–994, 2002
Biodegradability study of copolyesteramides based on diacid chlorides, diamines, and diols
Authors: Pivsa‐Art S. , Nakayama A. , Kawasaki N. , Yamamoto N. , Aiba S. 
Published: August 2002

AbstractCopolyesteramides were synthesized by polycondensation of diacid chlorides, diamines, and diols of varying methylene group chain length. The composition of the synthesized polymer was determined with nuclear magnetic resonance (NMR) analysis. The biodegradation of the polymers was evaluated both with enzymatic hydrolysis and activated sludge test. The polymers were hydrolyzed with lipases from Rhizopus arrhizus, Rhizopus delemar, Candida cylindracea, and an esterase from hog liver, whereas trypsin and α‐chymotrypsin did not have any apparent effect upon them. Enzymatic hydrolysis was found to be greatly affected by the polymer composition and structure. The degradation results obtained from the activated sludge test were in satisfactory agreement with those from enzymatic hydrolysis. The water‐soluble parts of hydrolyzed products were more susceptible to degradation of their ester bonds rather than their amide bonds. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 774–784, 2002
Influence of γ‐irradiation on poly(methyl methacrylate)
Authors: Suarez João Carlos Miguez , Mano Eloisa Biasotto , Da Costa Monteiro Elisabeth Ermel , Tavares Maria Inês Bruno 
Published: August 2002

AbstractPoly(methyl methacrylate) (PMMA) was γ‐irradiated (5–20 kGy) by a 137Cs source at room temperature in air. The changes in the molecular structure attributed to γ‐irradiation were studied by mechanical testing (flexure and hardness), size‐exclusion chromatography, differential scanning calorimetry, thermal gravimetric analysis, and both Fourier transform infrared and solution 13C‐NMR spectroscopy. Scanning electron microscopy was used to investigate the influence of the dose of γ rays on the fracture behavior of PMMA. The experimental results confirm that the PMMA degradation process involves chain scission. It was also observed that PMMA presents a brittle fracture mechanism and modifications in the color, becoming yellowish. The mechanical property curves show a similar pattern when the γ‐radiation dose increases. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 886–895, 2002
Polyanion/gelatin complexes as pH‐sensitive gels for controlled protein release
Authors: Jiang H. L. , Zhu K. J. 
Published: August 2002

AbstractPolyanion/gelatin complexes including poly(methacrylic acid) (PMAA)/gelatin, poly(acrylic acid) (PAA)/gelatin, and heparin/gelatin are investigated as pH‐sensitive gels for controlled protein release. Polyanions can interact with gelatin and form amorphous precipitates within a certain pH range, which is affected by the polyanion nature. The entrapment efficiency of model proteins (myoglobin, cytochrome c, and pepsin) into the complexes is rather high (>80%). By using a modified colloid titration that mixes a solution of gelatin and model proteins titrated with polyanion solution, myoglobin and cytochrome c are found to interact with polyanions by electrostatic forces at low pH, while pepsin either interacts with the polyanion when the pH is below its isoelectric point (IEP) or complexes with gelatin at a pH above IEPpepsin. At pH 7.4 all the complexes dissociate and proteins are rapidly released within a few hours. The complexes are stable and the proteins are retained within a certain pH range, which is related to the polyanion type (e.g., 5.0–2.0 for PMAA, 4.6–1.2 for PAA, and <4.3 for heparin). The three processes of complex formation, dissociation, and protein release have a good correlation. In addition, the protein release transition takes place within a rather narrow pH range (ca. 0.5 units) and the protein nature has little effect on the protein release profile. The high protein entrapment efficiency and good pH sensitivity of the protein release can be mainly attributed to the electrostatic attractive interactions between proteins and polyanion or gelatin. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1416–1425, 2001
Effect of composition and processing conditions on the chemical and morphological evolution of PA‐6/EPM/ EPM‐g‐MA blends in a corotating twin‐screw extruder
Authors: Machado A. V. , Covas J. A. , Walet M. , Van Duin M. 
Published: August 2002

AbstractThis study investigated the effect of blend composition and processing conditions on the chemical conversion and morphological evolution of PA‐6/EPM/EPM‐g‐MA blends along a twin‐screw extruder. The maleic anhydride (MA) content of the modified rubber was found to decrease strongly, to a level of almost zero, and in the melting zone the particle size was dramatically reduced, from millimeters to submicrometers. Blend composition had a secondary effect on both chemical conversion and morphological development. The processing conditions, particularly the temperature profile and the screw speed, affected both the chemical conversion and the morphological evolution. Using low temperatures and low screw rotation it was possible to follow in detail the evolution of morphological development of a reactive blend in a twin‐screw extruder. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1535–1546, 2001
Synthesis and characterization of poly(hydroxyether). II. Poly(hydroxyethers) based on various bisphenols and 2,2‐bis(4‐hydroxypheny)hexafluoropropane
Authors: Tatehata Hideki , Fukuoka Tetsuya , Mochizuki Akira 
Published: August 2002

AbstractSeveral kinds of linear copoly(hydroxyethers) (CPHEs) were prepared by the base‐induced condensation of bisphenol with epichlorohydrin in a polar mixed solvent. The CPHEs were based on bisphenol AF [2,2‐bis(4‐hydroxypheny)hexafluoropropane], and the composition ratio of bisphenol AF and bisphenol was 50 : 50 mol/mol. The CPHEs and the corresponding homopoly(hydroxyethers) (HPHEs) were characterized in terms of reduced viscosity, NMR, differential scanning calorimetry (DSC), solubility, and contact angle. NMR results indicated that the compositions of the copolymers were in good agreement with the feed compositions in the preparation. DSC analysis revealed that the CPHEs and HPHEs were amorphous polymers. The incorporation of bisphenol AF into the HPHE increased the solubility in many kinds of organic solvents when the CPHEs were compared with the corresponding HPHE. In the measurement of contact angles of water and plasma for poly(hydroxyethers) (PHEs) and common hydrophobic polymers, the peculiar phenomenon that the contact angles of plasma were higher than that of water was observed only in the case of PHEs. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1697–1709, 2001
Synthesis, spectral properties, and application of 1,8‐naphthalimide fluorophores for modified polymers
Authors: Philipova Tz. , Petkov I. 
Published: August 2002

AbstractThe presence of the epoxy group in the structure of 1,8‐naphthalimide fluorophores opens up possibilities to prepare compounds with new valued properties through covalent bonding to both polyamide and epoxy oligomers. Two new 4‐(1‐amino‐2,3‐epoxypropyl)‐9‐substituted‐1,8‐naphthalimides were synthesized, and their absorption and fluorescence characteristics were determined. The introduction of the substituent contributes to both the yellow color and strong fluorescence of the compounds, the quantum yield being about 0.9. The possibility for structural coloration of polyamide textile materials and epoxy oligomers has been investigated. The modified polymers are with intense green fluorescence, possessing a strong resistance to various physico‐chemical treatments and light. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1863–1869, 2001
Nonaqueous emulsion copolymerization of ethyl methacrylate/lauryl methacrylate in propylene glycol. I. Evaluation of stabilizing efficiency for PEO‐PS‐PEO triblock copolymers
Authors: You Xiaorong , Dimonie Victoria L. , Klein Andrew 
Published: August 2002

AbstractSixteen poly(ethylene oxide)–polystyrene–poly(ethylene oxide) (PEO‐PS‐PEO) triblock copolymers were synthesized by anionic polymerization. They were characterized by gel permeation chromatography and proton NMR. The molecular weight of these 16 PEO‐PS‐PEO triblock copolymers ranged from 5100 to 13,300. The polystyrene (PS) block length was between 13 and 41. The PEO block length was between 41 and 106. The polydispersity index for these PEO‐PS‐PEO triblock copolymers were 1.05 ± 0.02. When using these stabilizers in the emulsion copolymerization of ethyl methacrylate and lauryl methacylate in propylene glycol, only a narrow window of stability was observed. Stable latexes were formed only when the molecular weights of the PEO blocks were within the range of 5300–7700 and the molecular weights of the PS blocks were 2000–4000. The stabilizer ability for these triblock copolymers was correlated with their molecular weight and conformation in propylene glycol. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1951–1962, 2001
Kinetics of transesterification of dimethyl 2,6‐naphthalenedicarboxylate with 1,3‐propanediol
Authors: Stier U. , Gähr F. , Oppermann W. 
Published: August 2002

AbstractThe kinetics of transesterification of dimethyl 2,6‐naphthalenedicarboxylate (2,6‐DMN) with 1,3‐propanediol has been studied in the presence of various catalysts. The reaction was followed by measurement of the amount of methanol released, and the formation of oligomers with time. The oligomers obtained were quantitatively determined by high‐pressure liquid chromatography (HPLC). Interpretation of the experimental data showed that the transesterification followed Schulz‐Flory statistics. Therefore, one kinetic constant was sufficient to describe the kinetics of transesterification of 2,6‐DMN with 1,3‐propanediol. The kinetic constants observed, when different catalysts were employed, revealed the following activity sequence for the transesterification: Co(II) < Ti(IV) < Mn(II) < Zn(II). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2039–2046, 2001
Study on electrical conductivity of 2‐vinylpyridine‐methyl methacrylate copolymer in presence of cobalt acetate
Authors: Abed M. Yahia , Hindia Touson A. , Mohamed Manal G. , Mazrouaa Azza M. 
Published: August 2002

Abstract2‐Vinyl pyridine (2VP)‐methyl methacrylate (MMA) copolymers with different molar ratios were prepared. Their electrical properties were studied in the presence of Co(CH3COO)2. It was found that the electrical properties of the copolymer were changed by altering the molar ratio of 2VP : MMA and by varying the concentration of Co(CH3COO)2. The highest electrical conductivity was found when the 2VP : MMA molar ratio was 1 : 1. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2145–2153, 2001
Influence of some additives on state‐of‐mix, rheological, tensile, and dynamic mechanical properties in SBR compounds
Authors: Sirisinha Chakrit , Sittichokchuchai Weerapen 
Published: August 2002

AbstractThe influence of some additives (Flexon processing oil, Struktol WB 16 slipping agent, and Struktol NS 60 homogenizing resin) on state‐of‐mix, rheological, tensile, and dynamic mechanical properties were investigated. It was found that extrudate swell of the rubber compounds with either processing oil or NS 60 is governed mainly by the state‐of‐mix, but by wall slip in the case of compounds with WB 16. As for the dynamic mechanical properties, the plasticizing effect is the major factor controlling the properties in the case of processing oil, while the degree of crosslink and dilution effect are the main factors in the case of NS 60. Both degree of crosslink and state‐of‐mix are responsible for the dynamic mechanical properties in the case of WB 16. In addition, it was found that the tensile properties are controlled mainly by the plasticizing effect in the case of processing oil, but by the degree of crosslink in the cases of WB 16 and NS 60. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2474–2482, 2001
Selective retention properties to silver(I) and mercury(II) ions of poly(4‐vinylpyridine) methyl iodide studied by the liquid‐phase polymer‐based retention technique
Authors: Rivas B. L. , Pereira E. D. 
Published: August 2002

AbstractThe retention of various metal ions by water‐soluble poly(4‐vinylpyridine) methyl iodide in conjunction with ultrafiltration membrane was investigated. The method is based on the retention of inorganic ions by this polymer in a membrane filtration cell and subsequent separation of low‐molecular weight species from the polymer metal ion complex formed. It is shown that the polychelatogen can bind silver(I) and mercury(II) ions in aqueous solution at pH 1. At higher pH, the water‐soluble polymer can be applied to the separation and preconcentration of silver metal ions. Therefore, this polychelatogen is highly selective to Hg(II) at pH 1 with respect to metal ions such as Cd(II) and Zn(II). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2578–2582, 2001
Mechanical properties and fracture morphology of Al(OH)3/polypropylene composites modified by PP grafting with acrylic acid
Authors: Mai Kancheng , Li Zhengjun , Qiu Yuxin , Zeng Hanmin 
Published: August 2002

AbstractAl(OH)3/polypropylene (PP) composites modified by polypropylene grafted with acrylic acid (FPP) were prepared by melt extrusion. Effect of PP grafting with acrylic acid on mechanical properties and fracture morphology of Al(OH)3/polypropylene composites were investigated. Although incorporation of Al(OH)3reduced the mechanical properties of PP, addition of FPP increased the mechanical properties of Al(OH)3/PP composites. It is suggested that addition of FPP improve the dispersion of Al(OH)3and the interfacial interaction between filler and matrix. Mechanical properties of Al(OH)3/FPP/PP composites depend on the grafting rate and the content of FPP. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2617–2623, 2001