bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and surface properties of polystyrene‐graft‐poly(ethylene glycol) copolymers
Authors: Feng Li‐Bang , Zhou Shu‐Xue , You Bo , Wu Li‐Min 
Published: November 2006

AbstractPolystyrene‐graft‐poly(ethylene glycol) copolymers (PS‐g‐PEG) were successfully synthesized using the “grafting‐through” method. The graft copolymers and the surface properties of their coats were characterized by1H‐NMR, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), X‐ray photoelectron spectroscopy (XPS), static contact angle measurement, and atomic force microscopy (AFM). Both DSC and TEM indicated that the graft copolymers had a microphase separated structure. AFM showed the microphase separated structure also occurred at the coat surface, especially at high PEG content, which could also be indirectly confirmed by the XPS and contact angle results. The formation mechanism of the microphase separated structure was discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1458–1465, 2007
Systematic investigations of fatigue crack growth behavior of a PE‐HD pipe grade in through‐thickness direction
Authors: Balika W. , Pinter G. , Lang R. W. 
Published: November 2006

AbstractFatigue crack growth (FCG) experiments were performed on a commercial high‐density polyethylene (PE‐HD) pipe grade. To investigate the influence of different specimen types on FCG results, tests were conducted using compact tension (CT) specimens and cracked round bars (CRB). The effects of frequency and R‐ratio on FCG behavior were also studied. Furthermore, FCG tests were interrupted in the region of stable crack propagation. The crack front and the front of the process zone ahead of the crack were systematically characterized via microscopic methods in the thickness direction of the specimen. The experimental data are employed to study the mechanisms of process zone development and to determine the effective crack length by compliance relationships. This detailed information allows modeling FCG in PE‐HD at various positions in the thickness direction of the specimen. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103:1745–1758, 2007
Diffusion rates and the role of diffusion in solid propellant rocket motor adhesion
Authors: Grythe Kai F. , Hansen Finn K. 
Published: November 2006

AbstractDiffusion rates can give important information for the adhesion process across the bondline between insulation and propellant in solid propellant rocket motors. Diffusion coefficients of low molecular weight species such as crosslinkers and plasticizers have been measured by the weight of uptake method in polymer materials that are candidates for propellant contact. The materials were EPDM insulation sheets and “liners,” based on HTPB, HTPE, or GAP, and with different degrees of particle filling. Plots of relative mass gain as a function of the square root of time showed good linearity up to 20–50% weight increase and the diffusion coefficients could thus be determined with good accuracy. The diffusion coefficients for the low molecular weight isocyanates and plasticizers in these materials vary between 10−11 and 10−17 m2 s−1, dependent on material types and particle filling. In most cases, the results can be explained by the solubility parameters of the organic liquids and polymers. For the particle filled samples, the diffusion coefficients decrease with increasing degree of particle filling, and the decrease is faster than predicted by the Maxwell–Fricke or the Keller models for arrays of smooth spheres. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1529–1538, 2007
Lignin‐based polycondensation resins for wood adhesives
Authors: Mansouri N.‐E. El , Pizzi A. , Salvado J. 
Published: November 2006

AbstractLignin‐based wood adhesives are obtained that satisfy the requirements of relevant international standards for the manufacture of exterior‐grade wood particleboard. Formulations based on low molecular mass lignin and presenting an increase in the relative proportion of reactive points yield better results than the higher molecular mass lignin used in the past. These lignins allow a higher proportion of hydroxymethylation during preparation of methylolated lignins. These lignin‐based adhesives also yield acceptable results at particleboard pressing times that are sufficiently low to be of industrial significance. Lignin‐based wood adhesives, in which a nonvolatile nontoxic aldehyde (glyoxal) is substituted for formaldehyde in their preparation, are prepared and tested for application to wood panels such as particleboard. The adhesives yield good internal bond strength results for the panels, which are good enough to comfortably pass relevant international standard specifications for exterior‐grade panels. The adhesives also show sufficient reactivity to yield panels in press times comparable to that of formaldehyde‐based commercial adhesives. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1690–1699, 2007
Sorption and permeation behavior for CO2 in NH3‐plasma‐treated and untreated polystyrene membranes
Authors: Yang Y.‐S. , Kwak H. , Bae S.‐Y. , Kumazawa H. 
Published: November 2006

AbstractIn our preceding work, the simultaneous deviation from the conventional dual‐mode sorption and mobility model was observed in a case of CO2 in polystyrene (PS) membrane (glass transition temperature of pure polymer = 95°C) at 60 and 70°C. The plasticization effect of sorbed CO2 on both the sorption and diffusion processes tends to be brought about in glassy polymer membranes near the glass transition temperature. The behavior was simulated based on the concept that only one population of sorbed gas molecules of plasticizing ability to the polymer should exist. In the present work, the sorption and permeation behavior for CO2 in NH3‐plasma‐treated and untreated PS membranes at 40°C was investigated, where NH3‐plasma treatment was executed at plasma discharge powers of 40, 80, 120, and 160 W for an exposure time of 2 min. The sorption isotherm could be described by the sorption theory of Mi et al. (Macromolecules 1991, 24, 2361), where the glass transition temperature is depressed by a concentration of sorbed CO2 of plasticizing ability. NH3‐plasma treatment on PS membrane had little influence on the sorption behavior of CO2 at plasma discharge powers up to 160 W. The mean permeability coefficients were somewhat increased only at a discharge power of 160 W. At CO2 pressures below 0.9 MPa, the pressure dependencies of mean permeability coefficients for CO2 in both NH3‐plasma‐treated and untreated PS membranes at 40°C could also be simulated on the basis of the concept that only one population of sorbed gas molecules of plasticizing ability should exist. At CO2 pressures above 0.9 MPa, however, a plasticization action of sorbed CO2 had much more influence on the diffusion process rather than on the sorption one, and such a combined concept underestimated the mean permeability coefficient. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1798–1805, 2007
Optimization of elution conditions of chitosan gel and the study of its adsorbent mechanism
Authors: Tang Zhen‐Xing , Qian Jun‐Qing , Shi Lu‐E 
Published: November 2006

AbstractChitosan gel was prepared by crosslinking method. To make use of chitosan gel, the optimization of elution conditions and the adsorbent characteristics of chitosan gel were discussed in this article. The optimum elution conditions were c (NaCl) = 0.05 mol/L in Tris‐HCl (pH, 9.05) at the flow rate of 2.0–3.0 mL/min with chitosan gel (particle sizes, 120–140 μm). The effects of contact time, pH, initial BSA concentration, and temperature on adsorption were studied. The equilibrium data could be described well by Langmuir, Freundlich, and Redlich–Peterson models. Adsorption dynamics had been successfully studied by Langergren, intraparticle diffusion model and Avrami model. The thermodynamics parameters ΔG°, ΔH°, and ΔS° were calculated. The spectra studies indicated that the interaction between gel and protein was chiefly through electrostatic attraction in the shape of hydrogen bond. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1495–1506, 2007
Solid‐state polymerization of melt‐spun poly(ethylene terephthalate) fibers and their tensile properties
Authors: Nitta Sachiko , Yamaguchi Tomohiro , Ito Masayoshi 
Published: November 2006

AbstractThe production of high modulus and high strength poly(ethylene terephthalate) fibers was examined by using commercially available melt‐spun fibers with normal molecular weight (intrinsic viscosity = 0.6 dL/g). First, molecular weight of as‐spun fibers was increased up to 2.20 dL/g by a solid‐state polymerization, keeping the original shape of as‐spun fibers. Second, the polymerized as‐spun fibers were drawn by a conventional tensile drawing. The achieved tensile modulus and strength of as‐drawn fibers (without heat setting) were 20.0 and 1.1 GPa, respectively. A heat setting was carried out for the as‐drawn fibers. Tensile properties of the treated fibers were greatly affected by the condition of the heat setting. This was related to the increase of sample crystallinity and molecular degradation during the treatments. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1791–1797, 2007
Thermal and spectroscopic characterization of microbial poly(3‐hydroxybutyrate) submicrometer fibers prepared by electrospinning
Authors: Kim G.‐M. , Michler G. H. , Henning S. , Radusch H.‐J. , Wutzler A. 
Published: November 2006

AbstractSubmicrometer fibers based on the microbially synthesized ultra‐high‐molecular‐weight poly(3‐hydroxybutyrate) (PHB) were generated by an electrospinning (ES) process with chloroform as the solvent. To characterize the resulting electrospun fibers in comparison with the pure PHB before ES, differential scanning calorimetry, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy were performed. The diameters of the electrospun fibers characterized by SEM were in the range 400–1000 nm. Thermal analysis showed that the electrospun fibers contained both helical (α form) and trans‐zigzag (β form) crystals, whereas the solution‐cast PHB films mostly possessed the common helical structure. In addition, the crystallinity of the electrospun PHB fibers increased compared to that of the solution‐cast PHB films. Conformational changes occurred with the high extensional flow in the ES jets. Furthermore, the results from polarized FTIR measurements demonstrate that PHB molecules were oriented parallel to the fiber axis. As a result, the electrospun fibers exhibited strong birefringence under the polarized light. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1860–1867, 2007
Molecular weight and arm number of a star‐shaped styrene–butadiene block copolymer synthesized on a pilot‐vessel scale
Authors: Ma Rui , Zhang Lina 
Published: November 2006

AbstractTo improve the rheological properties and processability of industrial rubbers, star‐shaped styrene–butadiene–styrene (SBS) block copolymers were synthesized and characterized in this work. Through the variation of the ratio of divinylbenzene to the diblock anion, a series of SBS samples with three to six arms were prepared. Multi‐angle laser light scattering (MALLS) and size exclusion chromatography (SEC) combined with light scattering (LS) were used to determine the weight‐average molecular weight (Mw), radius of gyration (〈S2〉1/2), arm number, and chain conformation. The results from MALLS indicated that the Mw values of the star‐shaped SBS copolymers were 9.0, 13.0, 14.9, and 18.1 × 104, which corresponded to three, four, five, and six arms, respectively. There was a lot of Mw and 〈S2〉1/2 data for the many fractions in the SEC chromatograms of the SBS copolymers in tetrahydrofuran (THF) detected by LS, so the exponent of 〈S2〉1/2 = KMwα was determined to range from 0.59 to 0.30 for the samples having three to six arms. An analysis of the results revealed that the star SBS copolymers existed in a sphere conformation in THF, and their chain density increased with an increase in the arm number. The viscosity of the six‐arm SBS copolymer was reduced significantly, compared with that of the SBS samples having three to five arms, when their Mw values were similar. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1853–1859, 2007
Multiwall‐carbon‐nanotube‐reinforced poly(ethylene terephthalate) nanocomposites by melt compounding
Authors: Kim Jun Young , Park Hawe Soo , Kim Seong Hun 
Published: November 2006

AbstractPoly(ethylene terephthalate) (PET) nanocomposites reinforced with multiwall carbon nanotubes (MWCNTs) were prepared through melt compounding in a twin‐screw extruder. The presence of MWCNTs, which acted as good nucleating agents, enhanced the crystallization of PET through heterogeneous nucleation. The incorporation of a small quantity of MWCNTs improved the thermal stability of the PET/MWCNT nanocomposites. The mechanical properties of the PET/MWCNT nanocomposites increased with even a small quantity of MWCNTs. There was a significant dependence of the rheological properties of the PET/MWCNT nanocomposites on the MWCNT content. The MWCNT loading increased the shear‐thinning nature of the polymer‐nanocomposite melt. The storage modulus and loss modulus of the PET/MWCNT nanocomposites increased with increasing frequency, and this increment effect was more pronounced at lower frequencies. At higher MWCNT contents, the dominant nanotube–nanotube interactions led to the formation of interconnected or networklike structures of MWCNTs in the PET/MWCNT nanocomposites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1450–1457, 2007
New class of bioinspired lenses with a gradient refractive index
Authors: Jin Y. , Tai H. , Hiltner A. , Baer E. , Shirk James S. 
Published: November 2006

AbstractThe recognition that eye lenses in nature often employ a gradient refractive index to enhance the focusing power and to correct aberrations has motivated us to construct a synthetic lens using the layered concept encountered in biological lenses. The result is a highly flexible technology for the fabrication of gradient‐refractive index lenses that is based on a method of polymer forced assembly. Polymeric nanolayered films with incremental differences in the refractive index are assembled according to a prescribed design and molded into the desired shape. The exceptional flexibility of the process lies in the wide range of lens shapes and index profiles that can be realized. A lens with any refractive index distribution can be achieved within the refractive index range of available coextrudable optical materials. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1834–1841, 2007
Effect of the parent solution concentration on the flocculation performance of PAAm flocculants and the relation between the optimal parent solution concentration and critical concentrations
Authors: Zheng B. Q. , Qian J. W. , Li X. K. , Zhu Z. H. 
Published: November 2006

AbstractFlocculation performance of three kinds of polyacrylamide (PAAm), linear‐PAAm, Al(OH)3–PAAm hybrid, and star–PAAm, in kaolin suspensions have been investigated by Spectrophotometer. It was found that the flocculation performance of the polymer flocculant is enhanced at the beginning and then impaired with increasing parent solution concentration (Cp) and an optimal parent solution concentration (Cop) exists, which is directly proportional to both critical concentrations of C* and Cs of the polymer in the dilute aqueous solution, and can be roughly expressed by an empirical formula, Cop = 3.1 × 10−3 + 643.1Cs. The findings suggests that flocculation performance of a given polymer is dependent on both of the interchain association and the chain contact of the polymer chains in the parent solution and in the kaolin suspension, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1585–1592, 2007
Bankruptcy prediction by generalized additive models
Authors: Berg Daniel 
Published: November 2006

AbstractWe compare several accounting‐based models for bankruptcy prediction. The models are developed and tested on large data sets containing annual financial statements for Norwegian limited liability firms. Out‐of‐sample and out‐of‐time validation shows that generalized additive models significantly outperform popular models like linear discriminant analysis, generalized linear models and neural networks at all levels of risk. Further, important issues like default horizon and performance depreciation are examined. We clearly see a performance depreciation as the default horizon is increased and as time goes by. Finally a multi‐year model, developed on all available data from three consecutive years, is compared with a one‐year model, developed on data from the most recent year only. The multi‐year model exhibits a desirable robustness to yearly fluctuations that is not present in the one‐year model. Copyright © 2006 John Wiley & Sons, Ltd.
Feasibility of using the national hospital discharge survey to estimate the prevalence of selected birth defects
Authors: Boulet Sheree L. , Correa‐Villaseñor Adolfo , Hsia Jason , Atrash Hani 
Published: November 2006

AbstractBACKGROUND: Nationally representative data on the prevalence of certain birth defects are largely unavailable. We evaluated the feasibility of using data from the National Hospital Discharge Survey (NHDS) to describe the prevalence of selected birth defects. METHODS: All live births recorded in the NHDS during 1999–2001 were included. The prevalence for selected birth defects was calculated using weighted ratio estimators. Prevalence ratios comparing the NHDS estimates to published national estimates from the National Birth Defects Prevention Network (NBDPN) were calculated. RESULTS: With the exception of common truncus, the NHDS prevalence for the selected defects was consistently lower than the NBDPN estimates. The prevalence ratios ranged from 0.38 for trisomy 18 and anopthalmia/micropthalmia to 1.16 for common truncus. The NHDS prevalence estimates for spina bifida without anencephaly (PR 0.89, 95% CI: 0.57–1.22) and gastroschisis/omphalocele (PR 0.94, 95% CF: 0.48–1.40) most closely approximated the NBDPN estimates. CONCLUSIONS: NHDS data underestimate the prevalence of most birth defects. Additional research is needed to determine whether NHDS estimates may be useful for evaluating trends in certain conditions. Surveillance systems employing active case‐finding continue to provide more accurate estimates of birth defects prevalence. Birth Defects Research (Part A) 76:757–761, 2006. © 2006 Wiley‐Liss, Inc.
Role of geographic information systems in birth defects surveillance and research
Authors: Siffel Csaba , Strickland Matthew J. , Gardner Bennett R. , Kirby Russell S. , Correa Adolfo 
Published: November 2006

AbstractBACKGROUND: With the significant advancement of geographic information systems (GIS), mapping and evaluating the spatial distribution of health events has become easier. We examine the role of GIS in birth defects surveillance and research. METHODS: We briefly describe the geocoding process and potential problems in accuracy of the obtained geocodes, and some of the capabilities and limitations of GIS. We illustrate how GIS has been applied using the Metropolitan Atlanta Congenital Defects Program geocoded dataset. We provide some comments on potential data quality and confidentiality issues with birth defects in relation to GIS. RESULTS: It is desirable to geocode addresses using a multistrategy approach to achieve a high‐quality and accurate GIS dataset. Beyond the basic but important function of mapping, sophisticated statistical approaches and software are available to analyze the spatial or spatial‐temporal occurrence of birth defects, alone or in association with environmental hazards, and to present this information without compromising the confidentiality of the subjects. CONCLUSIONS: We recommend a broad and systematic use of GIS in birth defects spatial surveillance and research. © Birth Defects Research (Part A) 76:825–833, 2006. © 2006 Wiley–Liss, Inc.
Evaluation of the Texas Birth Defects Registry: An active surveillance system
Authors: Miller Eric 
Published: November 2006

AbstractBACKGROUND:Evaluations of surveillance systems are necessary to determine if the goals of the system are being met, how efficiently the surveillance is being implemented, and if resources are being used appropriately. An evaluation of the Texas Birth Defects Registry was conducted to assess the overall quality of data collection and to examine variations across regions of the state.METHODS:The registry was evaluated by using published guidelines for evaluating public health surveillance systems; the evaluation included staff interviews, process observation, and secondary data analysis.RESULTS:The registry monitors >370,000 births/year through active surveillance, with considerable disparities in workload across regions of the state. Because of the geographic size and substantial population of Texas, data collection is complex. However, the estimated sensitivity of the system appears sufficient, and rates for selected defects are highly comparable with other U.S. active birth‐defect surveillance systems. Registry staff continually monitor the quality of data collection and provide additional training. Amid unstable funding, the registry staff have demonstrated optimal foresight and flexibility to adapt and continue quality data collection. Timeliness needs to be improved and more consistent quality assurance is needed across regions of the state. Retaining staff and increasing visibility are essential to providing more stability.CONCLUSIONS:Active surveillance for birth defects is labor‐intensive but provides invaluable data for its stakeholders. The Texas Birth Defects Registry has proven to be a quality surveillance system and a beneficial resource for Texas. Birth Defects Research (Part A) 76:787–792, 2006. © 2006 Wiley‐Liss, Inc.
R‐stereopreference analysis of lipase Novozym®435 in kinetic resolution of flurbiprofen
Authors: Zhang Hua Yun , Wang Xin , Ching Chi Bun 
Published: November 2006

AbstractImmobilized lipase from Candida antarctica (Novozym®435) was employed in the kinetic resolution of racemic flurbiprofen by enantioselective esterification with methanol. It was found that the lipase has the R‐stereopreference and the reaction matches Bi Bi Ping Pong mechanism with dead‐end inhibition of methanol. Furthermore, the R‐stereopreference was analyzed in details from the aspects of enzymatic kinetic mechanism and reaction activation energy of both enantiomers. The R‐enantiomer shows lower activation energy and higher maximum reaction rate than the S‐enantiomer, which implies the R‐stereopreference of the lipase and makes the kinetic resolution of flurbiprofen via enzymatic reaction feasible. Chirality 2006. © 2006 Wiley‐Liss, Inc.
A Theoretical Investigation of the Gas‐Phase Oxidation Reaction of the Saturated tert‐Butyl Radical
Authors: Choi Jong‐Ho , Nam Mi‐Ja , Youn Sung‐Eui 
Published: November 2006

AbstractThe radical‐radical reaction mechanisms and dynamics of ground‐state atomic oxygen [O(3P)] with the saturated tert‐butyl radical (t‐C4H9) are investigated using the density functional method and the complete basis set model. Two distinctive reaction pathways are predicted to be in competition: addition and abstraction. The barrierless addition of O(3P) to t‐C4H9 leads to the formation of an energy‐rich intermediate (OC4H9) on the lowest doublet potential energy surface, which undergoes subsequent direct elimination or isomerization–elimination leading to various products: C3H6O+CH3, iso‐C4H8O+H, C3H7O+CH2, and iso‐C4H8+OH. The respective microscopic reaction processes examined with the aid of statistical calculations, predict that the major addition pathway is the formation of acetone (C3H6O)+CH3 through a low‐barrier, single‐step cleavage. For the direct, barrierless H‐atom abstraction mechanism producing iso‐C4H8 (isobutene)+OH, which was recently reported in gas‐phase crossed‐beam investigations, the reaction is described in terms of both an abstraction process (major) and a short‐lived addition dynamic complex (minor).