bluuebunny/crossref_metadata_2025_split huggingface dataset:
Beta‐globin gene cluster haplotypes as evidence of African gene flow to the northeastern coast of Venezuela
Authors: Vívenes De Lugo Merlyn , Rodríguez‐Larralde Alvaro , Castro de Guerra Dinorah 
Published: January 2003

AbstractIn order to study the origin of mutation HBB*S in Sucre and Anzoátegui states and the genetic affinities of these Venezuelan populations with other human groups, the β‐globin gene cluster haplotypes were determined for 28 sickle cell and/or S‐beta thalassemia patients and for 37 individuals with normal hematological parameters. Bantu, Benin, Senegal, and atypical haplotypes were identified in 50%, 36%, 2%, and 12% of the HBB*S chromosomes, respectively. Similar results have been published for Venezuelan patients from the central states, but a different trend is shown in a publication based on a group of patients from different regions of the country. For HBB*A, haplotype 2 (+ − − − −), characteristic of non‐African groups, was the most common (39%), followed by haplotype 3 (− − − − +) of African origin, and haplotype 6 (− + + − +), also typical of non‐Africans. The results reveal a high level of admixture of the Sucre–Anzoátegui population. The importance of specific conditions which have acted differently in the Venezuelan populations, such as founder effect, genetic drift, isolation, and endogamy are discussed. Genetic distances between the Sucre–Anzoátegui sample and several other human populations calculated on the basis of the HBB*S and HBB*A haplotypes revealed similar results, the closest genetic relationships being observed in relation to Bantu‐speaking groups. These results confirm the utility of the β‐globin haplotypes for population studies and contribute to knowledge of the Venezuelan gene pool. Am. J. Hum. Biol. 15:29–37, 2003. © 2002 Wiley‐Liss, Inc.
Obesity correlates with increased blood pressures in urban native American youth
Authors: Smith Chery , Rinderknecht Kimberly 
Published: January 2003

AbstractAlthough obesity is a growing problem with Native American youth living on reservations, little research has been conducted examining the prevalence of obesity and correlations between age, body composition, dietary intake, and blood pressures (BP) for urban Native youth. The purpose of this study was to investigate the relationship of these variables in urban Native American youth. Height and weight were measured for 155 Native American youth, age 5–18 years, and the body mass index (BMI) was calculated and classified into percentile categories. Skinfold thicknesses at the biceps, triceps, suprailiac, and subscapular sites, arm and waist circumferences, and systolic (SBP) and diastolic (DBP) blood pressures were also measured. There was a high proportion of obesity (>95 percentile) for youth in all age groups. The prevalence was 38% for the 5–10‐year‐olds and 45% for the 11–18‐year‐olds youth. There were no significant correlations between SBP and DBP and dietary variables. Mean SBP and DBP increased with increasing BMI percentiles. Stepwise regression analyses showed that waist circumference, age, and BMI were strong predictors for SBP, while waist circumference and age were predictors for DBP in the total sample. The findings suggest that overweight/obesity is very prevalent among urban Native American youth and the increased adiposity is associated with increased SBP and DBP. Am. J. Hum. Biol. 15:78–90, 2003. © 2002 Wiley‐Liss, Inc.
Minor physical anomalies in mentally healthy subjects: Internal consistency of the Waldrop Physical Anomaly Scale
Authors: Sivkov Stefan T. , Akabaliev Valentin H. 
Published: January 2003

AbstractThe aim of the study was to investigate the prevalence of minor physical anomalies in mentally healthy subjects by using the Waldrop Physical Anomaly Scale and to assess the reliability (internal consistency) of the scale. The subjects were 82 mentally healthy individuals (42 men, 40 women) of Bulgarian origin who were examined for minor physical anomalies. Mentally healthy individuals show a low mean score of minor physical anomalies. The anomalies prevail in the craniofacial region. The correlations between the anomalies are low, which implies poor internal consistency of the scale, probably due to the heterogeneity of the anomalies in terms of location, character, and time of prenatal development and adversity. Providing a base for comparative studies of developmental disorders, the findings infer the necessity of a more reliable scale for examination of informative morphogenetic variants which can distinguish between minor malformations and phenogenetic variants and suggest the period of prenatal adversity. Am. J. Hum. Biol. 15:61–67, 2003. © 2002 Wiley‐Liss, Inc.
Modification of cyanate ester resin by soluble polyimides
Authors: Iijima Takao , Kaise Tomohiro , Tomoi Masao 
Published: January 2003

AbstractSoluble polyimides (PIs) were prepared as random or multiblock types with 4,4′‐(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (s‐BPDA) as acid dianhydride components and 4,4′‐bis(m‐aminophenoxy) diphenyl sulfone (m‐BAPS) as a diamine component by a one‐pot process and used to improve the brittleness of the cyanate ester resin. Random‐type PIs were more effective as modifiers than multiblock‐type PIs. The morphologies of the modified resins depended on PI structure, molecular weight, and concentration. The most effective modification of the cyanate ester resin was attained because of a heterogeneous phase structure composed of a flat matrix phase and phase‐inverted structures of the modified resin; a 15 wt % inclusion of a random PI (weight‐average molecular weight = 63,400) composed of 6FDA, s‐BPDA, and m‐BAPS (0.5/0.5/1.0 molar ratio) led to a 65% increase in the fracture toughness for the modified resin with a slight loss of flexural strength and a retention of flexural modulus and glass‐transition temperature, compared with the values for the unmodified resin. Water absorptivity of the modified resin was comparable to that of the unmodified resin up to 400 h, and then, water absorption of the modified resins increased considerably. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1–11, 2003
Relationship between interfacial tension and dispersed‐phase particle size in polymer blends. II. PP/PA6
Authors: Shariatpanahi H. , Nazokdast H. , Hemmati M. 
Published: January 2003

AbstractSimple blends with different viscosity ratios of the components as well as compatibilized blends varying both in type and content of the compatibilizers were used to study the relation between the interfacial tension and the dispersed‐phase particle size for PP/PA6 (80/20 wt %) blends in this work. Four compatibilizing systems including poly(ethylene‐co‐methacrylic acid) ionomers, a maleic anhydride‐grafted propylene copolymer, maleic anhydride‐grafted polypropylene, and a maleic anhydride‐grafted styrene ethylene butylene copolymer were used. For blends prepared in an internal mixer, a power‐law relation was found between the capillary number and the torque ratio of the blends' components. This relation was used to estimate the interfacial tension for the compatibilized blends. The relation between the steady‐state torque of the blends as a measure of viscosity and the estimated values of interfacial tension were also investigated. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 54–63, 2003
Mechanical properties and morphology of PP/ABS blends compatibilized with PP‐g‐2‐HEMA
Authors: Patel Alpesh C. , Brahmbhatt Ragesh B. , Devi Surekha 
Published: January 2003

AbstractPolypropylene (PP) and acrylonitrile–butadiene–styrene blends of different composition were prepared using a single‐screw extruder. The binary blend of PP/ABS was observed to be incompatible and shows poor mechanical properties. PP‐g‐2‐hydroxyethyl methacrylate (2‐HEMA) was used as a compatibilizer for the PP/ABS blends. The ternary compatibilized blends of PP/ABS/PP‐g‐2‐HEMA showed improvement in the mechanical properties. Electron micrographs of these blends showed a homogeneous and finer distribution of the dispersed phase. The mechanical performance increased particularly in the PP‐rich blend. The 2.5‐phr (part per hundred of resin) compatibilizer was observed to bring improvement to the properties. The suitability of various existing theoretical models for the predication of the tensile moduli of these blends was examined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 72–78, 2003
Physical properties of PVA/PSSNa blends
Authors: Xu Ning , Zhou Dongshan , Li Liang , He Jinbo , Chen Wei , Wan Fen , Xue Gi 
Published: January 2003

AbstractBlends of conductive polymers with conventional nonconductive ones have, together, the virtues of good electroconductivity and good mechanical properties, whose prospect for electronic industrial application is very good. We prepared poly(vinyl alcohol) (PVA)–sodium polystyrene–sulfonate (PSSNa) blends through aqueous solution casting; the films are flexible and transparent, with electroconductivity that could reach 10−5 S/cm. The dependence of the electroconductivity on the weight fraction of PSSNa was found to follow the percolation theory. A general discussion is given on the factors that could influence the percolation threshold and the exponent. The films are stable in a 30% KOH solution and keep their conductivity after 10 days' exposure. Some mechanical properties are measured and the best mixing ratio is obtained for future use. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 79–87, 2003
Modeling of molecular weight distribution of gas‐phase polymerization of butadiene
Authors: Fang Dongyu , Sun Jianzhong , Zhou Qiyun 
Published: January 2003

AbstractA mathematical model of the molecular weight distribution (MWD) based on a multilayer model and an improved intrinsic kinetics model was proposed to simulate the MWD of the gas‐phase polymerization of butadiene with a heterogeneous catalyst. Intrinsic kinetics and heat and mass‐transfer resistances based on the multilayer model of a polymeric particle were considered in the modeling of the MWD. The effects of the reaction conditions, catalyst particle size, mass‐transfer resistance, deactivation of active sites, and transfer of the polymer chain on the molecular weight and MWD were simulated. The results show that the effects of the deactivation of active sites and transfer of the polymer chain on the average molecular weight are significant and that the effect of the catalyst particle size on the MWD is not significant. The simulation results of the molecular weight and MWD are compared with the experimental results. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 88–103, 2003
Electron spin resonance and ultraviolet spectral analysis of UV‐irradiated PVA films filled with MnCl2 and CrF3
Authors: Zidan H. M. 
Published: January 2003

AbstractPVA films with various filling levels of CrF3 and MnCl2 were prepared. ESR and UV/VIS optical analysis were used to shed more light on the structural modification that occur due to filling with different levels and/or UV irradiation. The ESR analysis revealed that the spin configuration of CrF3, MnCl2, and CoBr2‐filled PVA are different. The filling level dependence of ESR parameters was discussed. The UV‐VIS spectral analysis for pure PVA shows absorption bands at 265 and 280 nm, which were assigned to the presence of carbonyl groups. The addition of CrF3 led to the appearance of another bands at 418 and 596 nm. The filling level and/or UV irradiation have no effect on the position of absorption bands but the intensity of these bands has been changed. The addition of MnCl2 led to a new band at about 350 nm due to charge transfer transition. The ligand field parameters and optical energy gaps can be calculated and discussed. The results of optical and ESR analysis indicated that the Cr3+ or Mn2+ are present in its octahedral symmetrical form within the PVA Matrix. SEM micrographs of CrF3 filled PVA is discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 104–111, 2003
Thermally conductive nylon 6,6 and polycarbonate based resins. I. Synergistic effects of carbon fillers
Authors: Weber Erik H. , Clingerman Matthew L. , King Julia A. 
Published: January 2003

AbstractIncreasing the thermal conductivity of typically insulating polymers, such as nylon 6,6, opens new markets. A thermally conductive resin can be used for heat‐sink applications. This research focused on performing compounding runs followed by injection molding and thermal conductivity testing of carbon filled nylon 6,6 and polycarbonate based resins. The three carbon fillers investigated included an electrically conductive carbon black, synthetic graphite particles, and a milled pitch‐based carbon fiber. For each polymer, conductive resins were produced and tested that contained varying amounts of these single carbon fillers. In addition, combinations of fillers were investigated by conducting a full 23 factorial design and a complete replicate in each polymer. The objective of this article was to determine the effects and interactions of each filler on the thermal conductivity properties of the conductive resins. From the through‐plane thermal conductivity results, it was determined that for both nylon 6,6 and polycarbonate based resins, synthetic graphite particles caused the largest increase in composite thermal conductivity, followed by carbon fibers. The combination of synthetic graphite particles and carbon fiber had the third most important effect on composite thermal conductivity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 112–122, 2003
Thermally conductive nylon 6,6 and polycarbonate based resins. II. Modeling
Authors: Weber Erik H. , Clingerman Matthew L. , King Julia A. 
Published: January 2003

AbstractIncreasing the thermal conductivity of typically insulating polymers opens new markets. A thermally conductive resin can be used for heat‐sink applications. This research focused on extruding followed by injection molding and thermal conductivity testing of carbon filled nylon 6,6 and polycarbonate‐based resins. The three carbon fillers investigated included an electrically conductive carbon black, synthetic graphite particles, and a milled pitch‐based carbon fiber. For each polymer, conductive resins were produced and tested that contained varying amounts of these single carbon fillers. In addition, combinations of fillers were investigated by conducting a full 23 factorial design and a complete replicate in each polymer. These through‐plane thermal conductivity experimental results were then compared to results predicted by several different thermal conductivity models. An improved thermal conductivity model was developed that fit the experimental results well for resins that contained single fillers and combinations of different fillers. This improved model was based on the original Nielsen model. A single value for the shape parameter, A (which is needed in Nielsen's model), was used for all three different fillers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 123–130, 2003
Structural and physical properties of biodegradable copolyesters from poly(ethylene terephthalate) and polycaprolactone blends
Authors: Lim Kyung Yul , Kim Byoung Chul , Yoon Kee Jong 
Published: January 2003

AbstractThe relationship between the degree of ester‐interchange reactions and the physical properties in the melt blending of poly(ethylene terephthalate) (PET) and polycaprolactone (PCL) was investigated in terms of the blending time. 1H‐NMR and 13C‐NMR spectra confirmed that poly(ethylene terephthalate caprolactone) copolyesters were generated and became dominant at a blending time of more than 15 min, and this result may be related to the degree of the thermal decomposition of PCL. The spectra disclosed the effect of the blending time on the block characteristics of the ethylene terephthalate (ET) and caprolactone (CL) units of the copolyesters. The melting temperatures and heats of fusion assigned to the ET units in the copolyesters decreased with the blending time. However, the melting peak of the CL units disappeared when the blending time exceeded 20 min. For the CL block, the number of the average repeating units (5) proved to be the least critical value for crystallization. The crystallinity of the copolyesters was most notably reduced with a blending time up to 20 min. The total organic carbon (TOC) content of the copolyesters, a quantitative measure of biodegradability, increased steeply with the blending time up to 20 min. However, the TOC content increased slowly during extended blending. This agrees well with the recognized fact that the accession and penetration of lipase into copolyesters initiate in the amorphous region of the polymer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 131–138, 2003
Preparation and properties of highly functional copolyetheresters
Authors: Park Yun Heum , Kim Ki Young , Han Myong Hee 
Published: January 2003

AbstractBlock copolyetheresters with hard segments of poly(trimethylene 2,6‐naphthalene dicarboxylate) and soft segments of poly(tetramethylene ether)glycol 2,6‐naphthalene dicarboxylate were prepared by the melt polycondensation of dimethyl 2,6‐naphthalene dicarboxylate (NDC), 1,3‐propanediol (PD), and poly(tetramethylene ether)glycol (PTMEG) with molecular weights of 1000. The block copolyetheresters were characterized by 1H‐NMR spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis. The block copolyetheresters synthesized with NDC/PD/PTMEG were more heat resistant than those synthesized with dimethyl terephthalate/PD/PTMEG. The block copolyetheresters synthesized with NDC/PD/PTMEG showed stronger elastoplastic behavior than those synthesized with NDC/1,4‐butanediol/PTMEG. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 139–145, 2003
Graft mechanism of acrylonitrile onto starch by potassium permanganate
Authors: Zhang Liming , Gao Jianping , Tian Ruchuan , Yu Jiugao , Wang Wei 
Published: January 2003

AbstractThe graft mechanism of acrylonitrile (AN) onto starch under the initiation of potassium permanganate was investigated. The relationships of the grafting rate and the concentrations of potassium permanganate, AN, and backbone starch, as well as the reaction temperature, were established. On this basis, the equation for the rate of the graft copolymerization was derived, and the apparent activation energy for the graft copolymerization was obtained. Through the study of the oxidation reaction of starch with manganic ions, the valence changes of manganic ions during the graft copolymerization, and the grafting ability of different starch derivatives, together with electron spin resonance analysis, the grafting mechanism for the graft copolymerization of AN onto starch under the initiation of potassium permanganate was determined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 146–152, 2003
Thermotropic liquid‐crystalline polymers: Synthesis, characterization, and properties of poly(azomethine esters)
Authors: Shukla Utkarsh , Rao K. V. , Rakshit Animesh Kumar 
Published: January 2003

AbstractA series of poly(azomethine ester) copolymers were synthesized by the solution polycondensation method with different diamines. The synthesized polymers were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry (DSC), hot‐stage polarized microscopy, wide‐angle X‐ray diffraction, and solution viscosity. All polymers showed good thermal stability. The thermotropic liquid‐crystalline properties were examined by DSC and by microscopic observations. Except for one, all of the polymers showed nematic liquid‐crystalline behavior. The effects of temperature on crystallinity and the substituent on solubility, thermal stability, melting temperature, and viscosity were also studied. The voluminosity and shape factor were also computed from the viscosity data. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 153–160, 2003
Mathematical modeling of diffusion‐controlled free‐radical terpolymerization reactions
Authors: Keramopoulos Anastasios , Kiparissides Costas 
Published: January 2003

AbstractA comprehensive mathematical model is developed to describe the kinetics and molecular and compositional developments in a free‐radical terpolymerization batch reactor. This model is based on a fairly general kinetic mechanism, including chain‐transfer and terminal double‐bond reactions. We take into account the effects of diffusion‐controlled phenomena (i.e., gel, glass, and cage effects) on polymerization kinetics by extending our previous model on diffusion‐controlled reactions to terpolymerization systems. Triple moments for the live and dead trivariate chain‐length terpolymer composition distributions are introduced to describe the molecular and compositional developments in the terpolymerization system. The predictive capabilities of this model are demonstrated by simulation of the free‐radical, bulk terpolymerization of butyl acrylate/methyl methacrylate/vinyl acetate under different experimental conditions. It is shown that the model predictions are in good agreement with experimental data on monomer conversion, average molecular weights, and terpolymer composition, as reported by Dube and Penlidis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 161–176, 2003
Optical properties of block copolymers containing pendant carbazole groups and in situ synthesized CdS nanoclusters
Authors: Gratt Jason A. , Cohen Robert E. 
Published: January 2003

AbstractUltraviolet–visible absorption spectra and photoluminescence spectra were used to demonstrate efficient charge‐carrier migration in a novel bulk heterogeneous block copolymer system. One moiety of the block copolymer was functionalized with charge‐transporting carbazole groups, whereas the other block formed domains suitable for the in situ synthesis of CdS nanoclusters. The excitation of the cluster‐free copolymers with 350‐nm‐wavelength radiation led to a strong emission peak at 450 nm that was associated with the carbazole groups. When CdS clusters were present in nearby but spatially distinct domains, the carbazole emission was completely quenched and replaced by a very broad emission in the visible range (near 560 nm). The implications of these observations are discussed in the context of the energy‐transfer mechanism and possible device applications. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 177–182, 2003
Effect of nanosilica on the properties of polyester‐based polyurethane
Authors: Zhou Shu‐Xue , Wu Li‐Min , Sun Jian , Shen Wei‐Dian 
Published: January 2003

AbstractPolyester‐based polyurethanes with embedded nanosilica particles were prepared. The viscosity of polyester resins without and with nanosilica was determined by rheoviscometry. The morphology and mechanical and optical properties of the polyurethane coatings were studied intensively with a transmission electron microscope, a pendulum hardness tester, a scanning probe microscope, an Instron testing machine, an abrader and an ultraviolet–visible spectrophotometer. The viscosity of the polyester resins increased as the nanosilica content increased. Nanosilica could basically be dispersed into the polyester and its polyurethane on a nanoscale. The addition of a small amount of nanosilica increased the hardness, abrasion resistance, and tensile properties of the polymer films. However, these mechanical properties could be worsened at higher nanosilica contents. The ultraviolet–visible spectra showed that the absorbance and reflection of ultraviolet–visible light by the polyurethane films increased as the nano‐SiO2 content increased, especially at wavelengths of 290–400 nm. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 189–193, 2003