bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolutionary adaptation to high altitude: A view from in utero
Authors: Julian Colleen Glyde , Wilson Megan J. , Moore Lorna G.
Published: April 2009

A primary focus within biological anthropology has been to elucidate the processes of evolutionary adaptation. Frisancho helped to move anthropology towards more mechanistic explanations of human adaptation by drawing attention to the importance of the functional relevance of human variation. Using the natural laboratory of high altitude, he and others asked whether the unique physiology of indigenous high‐altitude residents was the result of acclimatization, developmental plasticity, and/or genetic adaptation in response to the high‐altitude environment. We approach the question of human adaptation to high altitude from a somewhat unique vantage point; namely, by examining physiological characteristics—pregnancy and pregnancy outcome—which are closely associated with reproductive fitness. Here we review the potent example of high‐altitude native population's resistance to hypoxia‐associated reductions in birth weight, which is often associated with higher infant morbidity and mortality at high altitude. With the exception of two recent publications, these comparative birth weight studies have utilized surnames, self‐identification, and/or linguistic characteristics to assess ancestry, and none have linked ‘advantageous’ phenotypes to specific genetic variations. Recent advancements in genetic and statistical tools have enabled us to assess individual ancestry with higher resolution, identify the genetic basis of complex phenotypes and to infer the effect of natural selection on specific gene regions. Using these technologies our studies are now directed to determine the genetic variations that underlie the mechanisms by which high‐altitude ancestry protects fetal growth and, in turn, to further our understanding of evolutionary processes involved in human adaptation to high altitude. Am. J. Hum. Biol., 2009. © 2009 Wiley‐Liss, Inc.
Pooled energy budget and human life history
Authors: Reiches Meredith W. , Ellison Peter T. , Lipson Susan F. , Sharrock Katherine C. , Gardiner Eliza , Duncan Laura G.
Published: April 2009

Human life history contains a series of paradoxes not easily explained by classical life history theory. Although overall reproductive output is higher than in related primates, juvenile growth is slower and age‐specific reproductive rates decline faster with age. A simple energetic model would predict that growth and reproductive rates should be positively correlated and that reproductive effort should not decelerate with age. The pattern of negative correlations in humans suggest the presence of trade‐offs among peak reproductive rate, childhood growth, and reproductive rate at older ages. To address this puzzle, we propose a synthesis of reproductive ecology and behavioral ecology focused on intra‐ and inter‐somatic energy transfers. This integration includes three concepts: the mother as final common pathway through which energy must pass to result in offspring; a distinction between direct and indirect reproductive effort, proposing the latter as a novel net energy allocation category relative to growth and direct reproductive effort; and a pooled energy budget representing the energetic contributions and withdrawals of all members of a breeding community. Individuals at all reproductive life stages are considered in light of their contributions to the pooled energy budget. Am. J. Hum. Biol., 2009. © 2009 Wiley‐Liss, Inc.
Cultural versus reproductive success: Why does economic development bring new tradeoffs?
Authors: Newson Lesley
Published: April 2009

Achievements that attract social rewards in developed countries, such as educational qualifications, a prestigious career, and the ability to acquire prestige goods, interfere with a woman's ability to achieve reproductive success. This tradeoff between cultural and reproductive success may have developed because economic development creates an evolutionarily novel social environment. In the social environment of developed countries, a far smaller proportion of social exchange is between kin than in the small‐scale communities in which the human brain and behavior evolved. Evidence suggests that social interaction between non‐kin is less likely to encourage behavior that enhances inclusive fitness. A model of the cultural change that is likely to result from this change in social influence suggests that beliefs and values will become increasingly less consistent with the pursuit of fitness (Newson et al. [2007]: Evol Hum Behav 28: 199–210). Responses to the World Value Survey, which has been carried out in over 70 countries, confirm a number of the predictions of this model. In countries where fertility began to decline more recently, people appear to perceive the costs of having children to be lower relative to the cost of childlessness and the benefits of being a parent. Am. J. Hum. Biol., 2009. © 2009 Wiley‐Liss, Inc.
Seasonal and circadian variation in salivary testosterone in rural Bolivian men
Authors: Vitzthum Virginia J. , Worthman Carol M. , Beall Cynthia M. , Thornburg Jonathan , Vargas Enrique , Villena Mercedes , Soria Rudy , Caceres Esperanza , Spielvogel Hilde
Published: April 2009

Testosterone (T) plays a key role in the increase and maintenance of muscle mass and bone density in adult men. Life history theory predicts that environmental stress may prompt a reallocation of such investments to those functions critical to survival. We tested this hypothesis in two studies of rural Bolivian adult men by comparing free T levels and circadian rhythms during late winter, which is especially severe, to those in less arduous seasons. For each pair of salivary TAM/TPM samples (collected in a ∼ 12‐h period), circadian rhythm was considered classic (CCLASSIC) if TAM > 110%TPM, reverse (CREVERSE) if TPM > 110%TAM, and flat (CFLAT) otherwise. We tested the hypotheses that mean TAM > mean TPM and that mean TLW < mean TOTHER (LW = late winter, OTHER = other seasons). In Study A, of 115 TPM–TAM pairs, 51% = CCLASSIC, 39% = CREVERSE, 10% = CFLAT; in Study B, of 184 TAM–TPM pairs, 55% = CCLASSIC, 33% = CREVERSE, 12% = CFLAT. Based on fitting linear mixed models, in both studies TOTHER‐AM > TOTHER‐PM (A: P = 0.035, B: P = 0.0005) and TOTHER‐AM > TLW‐AM (A: P = 0.054, B: P = 0.007); TPM did not vary seasonally, and T diurnality was not significant during late winter. T diurnality varied substantially between days within an individual, between individuals and between seasons, but neither T levels nor diurnality varied with age. These patterns may reflect the seasonally varying but unscheduled, life‐long, strenuous physical labor that typifies many non‐industrialized economies. These results also suggest that single morning samples may substantially underestimate peak circulating T for an individual and, most importantly, that exogenous signals may moderate diurnality and the trajectory of age‐related change in the male gonadal axis. Am. J. Hum. Biol., 2009. © 2009 Wiley‐Liss, Inc.
Gender‐specificCOMTVal158Met polymorphism association in Spanish schizophrenic patients
Authors: Hoenicka Janet , Garrido Elena , Martínez Isabel , Ponce Guillermo , Aragüés María , Rodríguez‐Jiménez Roberto , España‐Serrano Laura , Alvira‐Botero Ximena , Santos José Luis , Rubio Gabriel , Jiménez‐Arriero Miguel Ángel , Palomo Tomás ,   PARG
Published: April 2009

The functional Val158Met polymorphism (rs4680) located at the gene that codes for the catechol‐O‐methyltransferase (COMT) has been extensively investigated in schizophrenia although current data are still controversial. Since COMT activity is sexually dimorphic, we carried out two independent studies in homogeneous samples of male and female Spanish schizophrenic patients. In males, we found an association between the homozygous Val genotype and the disorder, which resembled a recessive model (P = 0.022; odds ratio [OR] = 1.67). This Val homozygotes overrepresentation is produced at the expense of the heterozygous individuals decrease, whilst the Met homozygotes showed no differences when compared controls and patients. As a consequence, the heterozygous genotype in this sample had a protective effect (P = 0.03; OR = 0.65) and a strong deviation from Hardy–Weinberg equilibrium in male cases was observed (P = 0.006). In addition, a 2‐SNP haplotype analysis (rs4818‐Val158Met) confirmed there is an overrepresentation of the different homozygous Val genotypes in the male schizophrenic sample. Regarding females, we did not find any statistically significant association betweenCOMTSNP and schizophrenia. In the light of this we suggest that the Val158Met SNP is involved in risk and protective genotypes for the vulnerability to schizophrenia in Spanish male population. © 2009 Wiley‐Liss, Inc.
Identification of neuroglycan C and interacting partners as potential susceptibility genes for schizophrenia in a Southern Chinese population
Authors: So Hon‐Cheong , Fong Pui Y. , Chen Ronald Y.L. , Hui Tomy C.K. , Ng Mandy Y.M. , Cherny Stacey S. , Mak William W.M. , Cheung Eric F.C. , Chan Raymond C.K. , Chen Eric Y.H. , Li Tao , Sham Pak C.
Published: April 2009

Chromosome 3p was reported by previous studies as one of the regions showing strong evidence of linkage with schizophrenia. We performed a fine‐mapping association study of a 6‐Mb high‐LD and gene‐rich region on 3p in a Southern Chinese sample of 489 schizophrenia patients and 519 controls to search for susceptibility genes. In the initial screen, 4 SNPs out of the 144 tag SNPs genotyped were nominally significant (P < 0.05). One of the most significant SNPs (rs3732530, P = 0.0048) was a non‐synonymous SNP in the neuroglycan C (NGC, also known as CSPG5) gene, which belongs to the neuregulin family. The gene prioritization program Endeavor ranked NGC 8th out of the 129 genes in the 6‐Mb region and the highest among the genes within the same LD block. Further genotyping of NGC revealed 3 more SNPs to be nominally associated with schizophrenia. Three other genes (NRG1, ErbB3, ErbB4) involved in the neuregulin pathways were subsequently genotyped. Interaction analysis by multifactor dimensionality reduction (MDR) revealed a significant two‐SNP interaction between NGC and NRG1 (P = 0.015) and three‐SNP interactions between NRG1 and ErbB4 (P = 0.009). The gene NGC is exclusively expressed in the brain. It is implicated in neurodevelopment in rats and was previously shown to promote neurite outgrowth. Methamphetamine, a drug that may induce psychotic symptoms, was reported to alter the expression of NGC. Taken together, these results suggest that NGC may be a novel candidate gene, and neuregulin signaling pathways may play an important role in schizophrenia. © 2009 Wiley‐Liss, Inc.
Dental topography and diets of four old world monkey species
Authors: Bunn Jonathan M. , Ungar Peter S.
Published: April 2009

Dental topographic analysis allows comparisons of variably worn teeth within and between species to infer relationships between dental form and diet in living primates, with implications for reconstructing feeding adaptations of fossil forms. Although analyses to date have been limited mainly to the M2s of a few primate taxa, these suggest that dental topographic analysis holds considerable promise. Still, larger samples including a greater range of species and different tooth types are needed to determine the potential of this approach. Here we examine dental topography of molar teeth of Cercocebus torquatus (n=48), Cercopithecus campbelli (n=50), Colobus polykomos (n=50), and Procolobus badius (n=50). This is the first such study of large samples of Old World monkeys, and the first to include analyses of both M1s and M2s. Average slope, relief, and surface angularity were computed and compared among tooth types, wear stages, and species. Results suggest that (1) data for M1s and M2s cannot be compared directly; (2) slope and relief decline with wear on M2s of all taxa, and M1s of the colobines, whereas angularity does not generally change except in the most worn specimens; and (3) folivorous colobines tend to have more sloping surfaces and more relief than do frugivorous cercopithecines, though angularity does not clearly separate taxa by diet. Am. J. Primatol. 71:466–477, 2009. © 2009 Wiley‐Liss, Inc.
Effects of high‐ and low‐fiber diets on fecal fermentation and fecal microbial populations of captive chimpanzees
Authors: Kišidayová Svetlana , Váradyová Zora , Pristaš Peter , Piknová Mária , Nigutová Katarína , Petrželková Klára J. , Profousová Ilona , Schovancová Kateřina , Kamler Jiří , Modrý David
Published: April 2009

We examined fiber fermentation capacity of captive chimpanzee fecal microflora from animals (n=2) eating low‐fiber diets (LFDs; 14% neutral detergent fiber (NDF) and 5% of cellulose) and high‐fiber diets (HFDs; 26% NDF and 15% of cellulose), using barley grain, meadow hay, wheat straw, and amorphous cellulose as substrates for in vitro gas production of feces. We also examined the effects of LFD or HFD on populations of eubacteria and archaea in chimpanzee feces. Fecal inoculum fermentation from the LFD animals resulted in a higher in vitro dry matter digestibility (IVDMD) and gas production than from the HFD animals. However, there was an interaction between different inocula and substrates on IVDMD, gas and methane production, and hydrogen recovery (P<0.001). On the other hand, HFD inoculum increased the production of total short‐chain fatty acids (SCFAs), acetate, and propionate with all tested substrates. The effect of the interaction between the inoculum and substrate on total SCFAs was not observed. Changes in fermentation activities were associated with changes in bacterial populations. DGGE of bacterial DNA revealed shift in population of both archaeal and eubacterial communities. However, a much more complex eubacterial population structure represented by many bands was observed compared with the less variable archaeal population in both diets. Some archaeal bands were related to the uncultured archaea from gastrointestinal tracts of homeothermic animals. Genomic DNA in the dominant eubacterial band in the HFD inoculum was confirmed to be closely related to DNA from Eubacterium biforme. Interestingly, the predominant band in the LFD inoculum represented DNA of probably new or yet‐to‐be‐sequenced species belonging to mycoplasms. Collectively, our results indicated that fecal microbial populations of the captive chimpanzees are not capable of extensive fiber fermentation; however, there was a positive effect of fiber content on SCFA production. Am. J. Primatol. 71:548–557, 2009. © 2009 Wiley‐Liss, Inc.
Reproductive parameters of wild Trachypithecus leucocephalus: seasonality, infant mortality and interbirth interval
Authors: Jin Tong , Wang De‐Zhi , Zhao Qing , Yin Li‐Jie , Qin Da‐Gong , Ran Wen‐Zhong , Pan Wen‐Shi
Published: April 2009

Understanding the reproductive parameters of endangered primate species is vital for evaluating the status of populations and developing adequate conservation measures. This study provides the first detailed analysis of the reproductive parameters of wild white‐headed langurs (Trachypithecus leucocephalus), based on demographic data collected over an 8‐year period in the Nongguan Karst Hills in Chongzuo County, Guangxi, China. From 1998 to 2002, a total of 133 live births were recorded in the population based on systematic censuses. Births occurred throughout the year, but the temporal pattern was highly correlated with seasonal variation in temperature and rainfall, with the birth peak coinciding with the dry and cold months of November–March. The average birthrate was 0.47±0.13 births per female per year and mortality for infants younger than 20 months was 15.8%. From 1998 to 2006, 14 females gave birth to 41 infants in four focal groups. The average age at first birth for female langurs was 5–6 years (n=5) and the interbirth interval (IBI) was 23.2±5.2 months (median=24.5 months, n=27). Infants are weaned at 19–21 months of age. The IBI for females with infant loss before weaning was significantly shorter than those for females whose infants survived. It appears that birth seasonality in the white‐headed langurs is influenced by seasonal changes in food availability. The timing of conceptions was found to coincide with peak food availability. The reproductive parameters for white‐headed langurs reported here are quite similar to those reported for other colobine species. One major difference is our observation of lower infant mortality in Trachypithecus. Am. J. Primatol. 71:558–566, 2009. © 2009 Wiley‐Liss, Inc.
On the flow‐phase diagram for nematic liquid crystalline polymer under magnetic field
Authors: Fu Shufang , Bai Jing
Published: April 2009

The effect of magnetic fields on molecular configuration of liquid crystalline polymers under shear flows are numerically analyzed using the extended Doi theory in which a molecular shape parameter is admitted. The evolution equation for the probability density function of the LCP molecules is directly solved without any closure approximations. One case is considered that the magnetic field makes 45° with respect to the flow direction. We can find that the magnetic fields strongly affect on the transition among flow‐orientation modes, such as tumbling, wagging, and aligning modes. And a new aligning flow‐orientation mode emerges at low shear rate, which is macroscopically same as the ordinary aligning mode, but is microscopically quite different from the ordinary one. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and properties of fluorinated biphenyl‐type epoxy resin
Authors: Ding J. P. , Tao Z. Q. , Fan L. , Yang S. Y.
Published: April 2009

A novel fluorinated biphenyl‐type epoxy resin (FBE) was synthesized by epoxidation of a fluorinated biphenyl‐type phenolic resin, which was prepared by the condensation of 3‐trifluoromethylphenol and 4,4′‐bismethoxymethylbiphenyl catalyzed in the presence of strong Lewis acid. Resin blends mixed by FBE with phenolic resin as curing agent showed low melt viscosity (1.3–2.5 Pa s) at 120–122°C. Experimental results indicated that the cured fluorinated epoxy resins possess good thermal stability with 5% weight loss under 409–415°C, high glass‐transition temperature of 139–151°C (determined by dynamic mechanical analysis), and outstanding mechanical properties with flexural strength of 117–121 MPa as well as tensile strength of 71–72 MPa. The thermally cured fluorinated biphenyl‐type epoxy resin also showed good electrical insulation properties with volume resistivity of 0.5–0.8 × 1017 Ω cm and surface resistivity of 0.8–4.6 × 1016 Ω. The measured dielectric constants at 1 MHz were in the range of 3.8–4.1 and the measured dielectric dissipation factors (tan δ) were in the range of 3.6–3.8 × 10−3. It was found that the fluorinated epoxy resins have improved dielectric properties, lower moisture adsorption, as well as better flame‐retardant properties compared with the corresponding commercial biphenyl‐type epoxy resins. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Nanomechanical characterization of single micron‐sized polymer particles
Authors: He J. Y. , Zhang Z. L. , Kristiansen H.
Published: April 2009

The mechanical characterization of single micron‐sized polymer particles is very important for understanding the anisotropic conductive adhesives interconnection. In this article, a nanoindentation‐based flat punch method was employed to investigate the mechanical properties of single polymer particles. A diamond flat tip, instead of a commonly used sharp tip for indentation, was specially designed to deform single polymer particles. The maximum applied load is 10 mN and the linear loading/unloading rate is 2 mN/s. Two types of amorphous polymer particles were examined. The polymer particles display significantly different stress–strain behaviors. The material responses at different strain levels were analyzed and compared. A particle size effect, the smaller the diameter, the harder the particle, on the compression stress–strain behavior, was observed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and properties of new poly(ether imides) based on pyridine‐containing aromatic dianhydride and diamine monomers
Authors: Wang Xiaolong , Li Yanfeng , Gong Chenliang , Ma Tao , Zhang Shujiang
Published: April 2009

A series of novel aromatic poly(ether imides) with inherent viscosities of 0.48–0.70 dL/g and weight‐average molecular weights of 18,800–40,500 g/mol were successfully prepared from two dianhydride and two diamine monomers containing pyridine moiety via both two‐step method and one‐step method. Comparison of the one‐step and the two‐step methods for the preparation of poly(ether imides) was carried out and shown that poly (ether imides) obtained via one‐step method exhibited higher molecular weights than the similar polymers prepared through two‐step process. Poly(ether imide) resins obtained via both one‐step and two‐step methods with subsequent chemical dehydration showed good solubility not only in high boiling point solvents but also in low boiling point solvents. High‐quality poly(ether imide) films could be obtained via the two‐step method with subsequent thermal imidization, which exhibited excellent thermal properties with glass transition temperatures of 239–278°C, initial decomposition temperatures of 540–574°C, residual weight percent at 800°C of 64.5–69.3% under nitrogen, good thermo‐oxidative stability with initial decomposition temperatures of 521–544°C, residual weight percent at 800°C of 33.6–51.1% under air atmosphere, outstanding mechanical properties with tensile strengths in the range of 104.6–109.4 MPa, tensile modulus in the range of 1.92–2.58 GPa, and elongation at break from 6.9 to 8.0%, as well as good transparency with cutoff wavelengths of 386–392 nm and low dielectric constants of 2.80–2.92 at 1 MHz. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis of polyimide oligomer attached with hemicyanine dye
Authors: Qin Chuanxiang , Wang Jianjun , Li Yi , Xie Hongde , Wang Xinbo , Dai Lixing , Wang Xiaomei , Chen Guoqiang
Published: April 2009

Two hemicyanine dyes, trans‐4‐[p‐(N,N‐di(2‐hydroxyethyl)) amino‐styryl]‐N‐methylpyridinium tetraphenylborate (dye‐C1) and trans‐4‐[p‐(N,N‐di(2‐hydroxyethyl)) amino‐styryl]‐N‐octylpyridinium tetraphenylborate (dye‐C8) were synthesized, and characterized by infrared, 1H‐NMR, thermoanalysis, respectively. Then polyimide (PI) oligomers (referred to as P‐C1 and P‐C8) with these hemicyanine dyes attached to the polymer side chain were prepared through Mitsunobu condensation. When the linear optical properties of the two dyes and the two PI oligomers were studied in dimethylformamide solvent, there were obvious blue shifts in the spectra of the oligomers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Evaluation of biodegradability of epoxy‐guar gum composites
Authors: D'Melo D. J. , Shenoy M. A.
Published: April 2009

Epoxy composites incorporating natural components have been mainly limited to the use of natural fibers. However, there have been a few instances where polysaccharides have been used as particulate fillers in thermoset compositions. The present study investigated the effect of guar gum/hydroxypropyl guar gum as a filler on the degradative properties of epoxy composites at various filler concentrations, with reference to fungal degradation and soil burial tests. It was found that at higher filler concentrations, the degradation increased. Composites based on hydroxypropyl guar gum showed increased degradation initially but on prolonged exposure to the fungal environment, the difference between guar gum and the hydroxypropyl guar gum‐based composites was found to be marginal. Microscopic evaluation of the composites showed that the degradation occurred at both the composite surface and in the bulk. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Lignin in jute fabric–polypropylene composites
Authors: Acha B. A. , Marcovich N. E. , Reboredo M. M.
Published: April 2009

In this work, the feasibility of using lignin as a compatibilizer for composites made from jute fiber fabric and polypropylene (PP) was studied. Since lignin contains polar (hydroxyl) groups and nonpolar hydrocarbon, it was expected to be able to improve the compatibility between the two components of the composite. It was found that lignin acted as β nucleation, fire retardant, and toughening agent for PP matrix. Jute composites exhibit higher stiffness, tensile strength, and impact behavior in respect to those of neat PP. Although scanning electron micrographic observations indicate that PP‐jute adhesion was slightly improved by lignin addition, additional benefits were only obtained from impact behavior. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Temperature dependence of the conductivity behavior of graphite nanoplatelet‐filled epoxy resin composites
Authors: Zheng Chao , Fan Zhuangjun , Wei Tong , Luo Guilian
Published: April 2009

In this article, epoxy/graphite nanoplatelet (GNP) conductive composites with the low percolation threshold of ∼ 0.5 vol % were prepared. The effect of microstructure, particularly the spatial distribution of fillers in the matrix on the resistivity and its dependence on temperature, also was investigated. It is suggested that the high aspect ratio and good distribution of GNPs in the matrix contribute to the low threshold of the composite. The thermal–electrical behavior of the composite is also significantly influenced by the GNP content and microstructure of the composite. When the GNP content is greater than percolation threshold, a noticeable positive temperature coefficient of resistivity disappears. It is explained by the unique conductive network formed by plane contact between GNPs, which is hardly affected by the expansion of matrix during heating. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Graft copolymerization of maleic anhydride onto low‐molecular‐weight polyisobutylene through solvothermal method
Authors: Gong Wenjuan , Qi Rongrong
Published: April 2009

The free‐radical graft copolymerization of maleic anhydride (MAH) onto highly reactive low molecular weight polyisobutylene was conducted by the use of benzoyl peroxide as an initiator through the solvothermal method. Fourier transform infrared spectra and 1H‐NMR spectra confirmed that maleic anhydride was successfully grafted onto highly reactive low molecular weight polyisobutylene backbone, and the grafting mechanism also was proposed. The effect of benzoyl peroxide content, MAH concentration, total reactant amount in the reaction vessels, reaction temperature and time, and different kinds and volumes of solvents on MAH's degree of grafting was investigated in detail. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Effect of interfacial interaction on the crystallization and mechanical properties of PP/nano‐CaCO3 composites modified by compatibilizers
Authors: Wang Yuhai , Shen Hao , Li Gu , Mai Kancheng
Published: April 2009

To investigate the effect of interfacial interaction on the crystallization and mechanical properties of polypropylene (PP)/nano‐CaCO3 composites, three kinds of compatibilizers [PP grafted with maleic anhydride (PP‐g‐MA), ethylene–octene copolymer grafted with MA (POE‐g‐MA), and ethylene–vinyl acetate copolymer grafted with MA (EVA‐g‐MA)] with the same polar groups (MA) but different backbones were used as compatibilizers to obtain various interfacial interactions among nano‐CaCO3, compatibilizer, and PP. The results indicated that compatibilizers encapsulated nano‐CaCO3 particles, forming a core–shell structure, and two interfaces were obtained in the compatibilized composites: interface between PP and compatibilizer and interface between compatibilizer and nano‐CaCO3 particles. The crystallization and mechanical properties of PP/nano‐CaCO3 composites were dependent on the interfacial interactions of these two interfaces, especially the interfacial interaction between PP and compatibilizer. The good compatibility between PP chain in PP‐g‐MA and PP matrix improved the dispersion of nano‐CaCO3 particles, favored the nucleation effect of nano‐CaCO3, increased the tensile strength and modulus, but reduced the ductility and impact strength of composites. The partial compatibility between POE in POE‐g‐MA and PP matrix had little effect on crystallization and mechanical properties of PP/nano‐CaCO3 composites. The poor compatibility between EVA in EVA‐g‐MA and PP matrix retarded the nucleation effect of nano‐CaCO3, and reduced the tensile strength, modulus, and impact strength. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Semi‐interpenetrating networks based on poly(N‐isopropyl acrylamide) and poly(N‐vinylpyrrolidone)
Authors: Žugić Dragana , Spasojević Pavle , Petrović Zoran , Djonlagić Jasna
Published: April 2009

Three series of novel semi‐interpenetrating polymer networks, based on crosslinked poly(N‐isopropylacrylamide), PNIPA, and different amounts of the linear poly(N‐vinylpyrrolidone), PVP, were synthesized to improve the mechanical properties and thermal response of PNIPA gels. The effect of the incorporation of the linear PVP into the temperature responsive networks on the temperature‐induced transition, swelling/deswelling behavior, and mechanical properties was studied. Polymer networks with four different crosslinking densities were prepared with varying molar ratios (25/1 to 100/1) of the monomer (N‐isopropylacrylamide) to the crosslinker (N,N′‐methylenebisacrylamide). The hydrogels were characterized by determination of the equilibrium degree of swelling, the dynamic shear modulus and the effective crosslinking density, as well as tensile strength and elongation at break. Furthermore, the deswelling kinetics of the hydrogels was studied by measuring their water retention capacity. The inclusion of the linear hydrophilic PVP in the PNIPA networks increased the equilibrium degree of swelling. The tensile strength of the semi‐interpenetrating networks (SIPNs) reinforced with linear PVP was higher than that of the PNIPA networks. The elongation at break of these SIPNs varied between 22% and 55%, which are 22 – 41% larger than those for pure PNIPA networks. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Investigation on fluorescence properties of ultrafine PVA fiber mats‐contained polyoxometalate with different molecular structure
Authors: Sun Yongling , Shan Yuping , Cui Xiujun , Li Bin , Gong Jian , Su Zhongmin , Qu Lunyu
Published: April 2009

Novel luminescence ultrafine fiber mats containing K11[Eu(PW11O39)2] [EuPW11] and Na9[EuW10O36] [EuW10] entrapped in polyvinyl alcohol (PVA) have been successfully prepared by electrospinning method. By comparing the luminescence emission spectra of EuPW11/PVA and EuW10/PVA ultrafine fiber mats, we conclude lower site symmetry of Eu3+ in the EuPW11/PVA ultrafine fiber mats. We further investigate the different configurations of EuPW11 and EuW10, which lead to the different site symmetry of Eu3+ in the ultrafine fiber mats of EuPW11/PVA and EuW10/PVA. Fluorescence property shows EuPW11/PVA ultrafine fiber mats display pure red emission. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Physical, structural, and mechanical characterization of calcium–shellac microspheres as a carrier of carbamide peroxide
Authors: Xue Jing , Zhang Zhibing
Published: April 2009

Calcium–shellac microspheres with encapsulated carbamide peroxide (CP) were made by emulsification to generate an emulsion including shellac ammonium salt aqueous solution with soluble CP dispersed in sunflower oil with calcium chloride powders, followed by gelation between shellac and calcium. The effects of formulation and processing conditions on the encapsulation efficiency of CP, the physical, structural, and mechanical properties of calcium–shellac microspheres, including size, inner structure, and mechanical strength, were investigated. The sizes of the prepared microspheres were in the range of 10–100 μm, depending on the agitation speed used in the emulsification process. The morphology of calcium–shellac microspheres was characterized using scanning electron microscopy and image analysis. Their inner structure was evaluated using X‐ray microcomputed tomography, and their mechanical strength was determined by a micromanipulation technique. The structure and mechanical strength of the microspheres were compared with those bigger calcium–shellac beads (1–3 mm in diameter) made by extrusion followed by gelation (Xue and Zhang, J Microencapsul 2008, 25, 523), and clear contrast in the properties between the two preparation methods has been found. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Predictability of apparent viscosity in a vibratory shearing flow field
Authors: Qu Jin‐Ping , Wei Bao‐Hua , Yang Zhi‐Tao , Cai Yong‐Hong
Published: April 2009

A self‐developed experimental facility by the National Engineering Research Center of Novel Equipment for Polymer Processing, called a coaxial barrel dynamic rheometer, was used to test the predictability of the apparent viscosity equations of polymer melts in flat vibrating shear flows. The testing principle of the rheometer is to transform the shear power of a motor and extrusion pressure in a shear field to melt viscosity. The shear field can simulate an orthogonal superposed vibratory flow, boundary vibrating pressure flow, and their combined flow. By comparing equation predictions with experimental results, we show a qualitatively satisfactory and quantitatively reasonable predictive ability, which verifies the work of our mathematical derivations. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Nylon 6/Brazilian clay membranes prepared by phase inversion
Authors: Leite Amanda M. D. , Maia Larissa F. , Araújo Edcleide M. , Lira Hélio L.
Published: April 2009

Microporous membranes were synthesized from a polymer nanocomposite material, intercalated montmorillonite clay/nylon 6, by an immersion–precipitation method in a water bath. This membrane was skinless and was composed of cellular pores and sheaflike crystallites, which were interwoven into a bicontinuous structure. In contrast, pure nylon 6, precipitated under the same conditions, yielded a skinned asymmetric membrane. The X‐ray diffraction patterns showed that the nanocomposites and the membranes exhibited exfoliated structures. By differential scanning calorimetry, it was observed that the clay probably acted as a reinforcing filler, increasing the crystallinity degree of the nanocomposites, but it was practically unchanged in the membranes. Through photomicrographs obtained by scanning electron microscopy, it was possible to verify that all the membranes exhibited an asymmetric morphology with a well‐defined porous structure and a tight skin with a cellular sublayer. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Mechanical properties of silane‐treated, silica‐particle‐filled polyisoprene rubber composites: Effects of the loading amount and alkoxy group numbers of a silane coupling agent containing mercapto groups
Authors: Nakamura Yoshinobu , Honda Hiroaki , Harada Atsushi , Fujii Syuji , Nagata Kazuya
Published: April 2009

The surface treatment of spherical silica particles with a silane coupling agent with mercapto groups was carried out. The treated silica particles were incorporated within polyisoprene and then vulcanized. The effects of the loading amount and alkoxy group number of silane on the stress–strain curve of the filled composite were investigated. For this purpose, silanes with dialkoxy and trialkoxy structures were used. The loading amount of silane on the silica surface was varied from 1 to 8 times the amount required for monolayer coverage. The stress at the same strain increased with the silane treatment, and it was higher in the dialkoxy structure than in the trialkoxy structure above 300% strain. There was no significant influence of the loading amount on the stress for the trialkoxy silane structure. However, the stress was influenced by the loading amount, and the maximum stress was observed at 4 times the silane amount required for monolayer coverage for the dialkoxy structure. The stress had a good relationship with the crosslinking density of silica‐filled polyisoprene rubber (measured with a swelling test). The reinforcement effect by the silane treatment of silica was found to be affected strongly both by the entanglement of the silane chain and polyisoprene rubber matrix and by the crosslinking reaction between the mercapto group of silane and polyisoprene rubber in the interfacial region. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Misclassification rates, critical values and size of the design in measurement systems capability studies
Authors: Zappa D. , Deldossi L.
Published: April 2009

Measurement systems capability analysis aims to test if the variability of a measurement system is small relative to the variability of a monitored process. At present some open questions are related both to the interpretation of the critical values of the indices typically used by practitioners to assess the capability of a gauge and to the choice of the size of the experimental design to test the repeatability and the reproducibility of the measurement process. In this paper, starting from the misclassification rates of a measurement system, we present a solution to these issues. Copyright © 2009 John Wiley & Sons, Ltd.
On the detection of high‐frequency oscillations in short gamma‐ray bursts
Authors: Zhilyaev B.E. , Dubinovska D.
Published: April 2009

In this work we present the results of an investigation aimed at a search for an oscillatory phenomenon during short gamma‐ray bursts. The wavelet technique, used for this analysis, is applied to the data from the BATSE 3B catalogue. We have detected oscillations, which periods are found to be in the milliseconds range and their amplitudes up to dozens of percents. A possible scenario for such a phenomenon is the coalescence of stellar‐mass black holes and neutron stars. During the coalescence process the matter orbiting the black hole produces rapid, periodic phenomena. Such system will also emit gravitational waves which cause the orbital radius to decrease and leads to the emission of a chirp of radiation. Estimates lead to a timescale of milliseconds for the coalescence process and oscillation frequencies of hundreds of Hz. The gamma‐ray bursts considered in this paper, show both frequencies and survival times of oscillations close to the mentioned values. A chirp phenomenon is also present. We therefore argue in favor of the black hole – neutron star coalescence as a scenario for the production of short gamma‐ray bursts (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Two‐dimension potentials which generate spatial families of orbits
Authors: Anisiu M.‐C. , Bozis G.
Published: April 2009

We consider the following case of the 3D inverse problem of dynamics: Given a spatial two‐parametric family of curves f (x, y, z) = c1, g (x, y, z) = c2, find possibly existing two‐dimension potentials under whose action the curves of the family are trajectories for a unit mass particle. First we establish the conditions which must be fulfilled by the family so that potentials of the form w (y, z) give rise to the curves of the family, and we present some applications. Then we examine briefly the existence of potentials depending on (x, z), respectively (x, y), which are compatible with the given family (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The chromospherically active binary star EI Eridani: II. Long‐term Doppler imaging
Authors: Washuettl A. , Strassmeier K.G. , Weber M.
Published: April 2009

Data from 11 years of continuous spectroscopic observations of the active RS CVn‐type binary star EI Eridani – gained at NSO/McMath‐Pierce, KPNO/Coudé Feed and during the MUSICOS 98 campaign – were used to obtain 34 Doppler maps in three spectroscopic lines for 32 epochs, 28 of which are independent of each other. Various parameters are extracted from our Doppler maps: average temperature, fractional spottedness, and longitudinal and latitudinal spot‐occurrence functions. We find that none of these parameters show a distinct variation nor a correlation with the proposed activity cycle as seen from photometric long‐term observations. This suggests that the photometric brightness cycle may not necessarily be due to just a cool spot cycle. The general morphology of the spot pattern remains persistent over the whole period of 11 years. A large cap‐like polar spot was recovered from all our images. A high degree of variable activity was noticed near latitudes of ≈60–70° where the appendages of the polar spot emerged and dissolved (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Intermediate‐term variations in solar radius during solar cycle 23
Authors: Kiliç H. , Golbasi O. , Chollet F.
Published: April 2009

In this study, we look for the mid‐term variations in the daily average data of solar radius measurements made at the Solar Astrolabe Station of TUBITAK National Observatory (TUG) during solar cycle 23 for a time interval from 2000 February 26 to 2006 November 15. Due to the weather conditions and seasonal effect dependent on the latitude, the data series has the temporal gaps. For spectral analysis of the data series, thus, we use the Date Compensated Discrete Fourier Transform (DCDFT) and the CLEANest algorithm, which are powerful methods for irregularly spaced data. The CLEANest spectra of the solar radius data exhibit several significant mid‐term periodicities at 393.2, 338.9, 206.5, 195.2, 172.3 and 125.4 days which are consistent with periods detected in several solar time series by several authors during different solar cycles. The knowledge relating to the origin of solar radius variations is not yet present. To see whether these variations will repeat in next cycles and to understand how the amplitudes of such variations change with different phases of the solar cycles, we need more systematic efforts and the long‐term homogeneous data. Since most of the periodicities detected in the present study are frequently seen in solar activity indicators, it is thought that the physical mechanisms driving the periodicities of solar activity may also be effective in solar radius variations (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
New magnetic field measurements of β Cephei stars and slowly pulsating B stars
Authors: Hubrig S. , Briquet M. , De Cat P. , Schöller M. , Morel T. , Ilyin I.
Published: April 2009

We present the results of the continuation of our magnetic survey with FORS 1 at the VLT of a sample of B‐type stars consisting of confirmed or candidate β Cephei stars and Slowly Pulsating B (hereafter SPB) stars, along with a small number of normal B‐type stars. A weak mean longitudinal magnetic field of the order of a few hundred Gauss was detected in three β Cephei stars and two stars suspected to be β Cephei stars, in five SPB stars and eight stars suspected to be SPB stars. Additionally, a longitudinal magnetic field at a level larger than 3σ has been diagnosed in two normal B‐type stars, the nitrogen‐rich early B‐type star HD 52089 and in the B5 IV star HD 153716. Roughly one third of β Cephei stars have detected magnetic fields: Out of 13 β Cephei stars studied to date with FORS 1, four stars possess weak magnetic fields, and out of the sample of six suspected β Cephei stars two show a weak magnetic field. The fraction of magnetic SPBs and candidate SPBs is found to be higher: Roughly half of the 34 SPB stars have been found to be magnetic and among the 16 candidate SPBs eight stars possess magnetic fields. In an attempt to understand why only a fraction of pulsating stars exhibit magnetic fields, we studied the position of magnetic and non‐magnetic pulsating stars in the H‐R diagram. We find that their domains in the H‐R diagram largely overlap, and no clear picture emerges as to the possible evolution of the magnetic field across the main sequence. It is possible that stronger fields tend to be found in stars with lower pulsating frequencies and smaller pulsating amplitudes. A somewhat similar trend is found if we consider a correlation between the field strength and the v sin i ‐values, i.e. stronger magnetic fields tend to be found in more slowly rotating stars (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The estimations of neutron star mass and radius by the kHz QPOs
Authors: Zhang C.M.
Published: April 2009

The kHz quasi‐periodic oscillations (QPOs) have been detected by the RXTE satellite in about thirty neutron stars (NSs) in low mass X‐ray binaries (LMXBs), which are usually interpreted to be related to the Keplerian motions in the orbit close to NS surface where the accreted matter is sucked onto the star. Based on the MHD Alfvén wave oscillation model and the relativistic precession model for the neutron star (NS) kHz QPOs, estimations of mass M and radius R of some NSs are given, which can give clues to evaluate the models. Furthermore, comparisons with theoretical M ‐R relations by stellar equations of state (EOSs) are presented (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic activity on 12 Cam and 29 Dra from long‐term photometry
Authors: Zboril M. , Messina S.
Published: April 2009

We present newly discovered magnetic cycles of two late‐type and long‐period SB1 systems: 12 Cam and 29 Dra. The long‐term photometry study revealed the presence of magnetic multiperiodic cycles on both stars, namely 14.8 and 8.5 yr for 12 Cam and 20.3, 11.1, and 7.6 yr for 29 Dra. Furthermore, the modelling of the V ‐band light curves revealed the existence of two active longitudes on 12 Cam and probably on 29 Dra as well. Both stars show changes of rotational period. The 12 Cam is the slowest rotating star whose activity cycle has been determined. The activity cycles determined by us allow us to extend to the slower rotation regime and to improve the significance of the empirical relation between rotation period and magnetic cycle length (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
How semiregular are irregular variables?
Authors: Lebzelter T. , Obbrugger M.
Published: April 2009

We investigate the question whether there is a real difference in the light change between stars classified as semiregular (SRV) or irregular (Lb) variables by analysing photometric light curves of 12 representatives of each class. Using Fourier analysis we try to find a periodic signal in each light curve and determine the S/N of this signal. For all stars, independent of their variability class we detect a period above the significance threshold. No difference in the measured S/N between the two classes could be found. We propose that the Lb stars can be seen as an extension of the SRVs towards shorter periods and smaller amplitudes. This is in agreement with findings from other quantities which also showed no marked difference between the two classes (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
To what extent do investors in a financial market anchor their judgments excessively? Evidence from the Hong Kong horserace betting market
Authors: Johnson Johnnie Eric Victor , Schnytzer Adi , Liu Shuang
Published: April 2009

A naturalistic study was employed to explore a new form of “basic anchoring.” In particular, we examined the degree to which decision makers in a financial market, the horserace betting market, anchored their probability judgments excessively on a factor present in the environment at the time the judgments were made and which was relevant and informative to the judgment: the advantage afforded by a horse's barrier‐position (BP). The results demonstrated that under certain conditions bettors anchored excessively on BP information revealed at previous race meetings, but not on the most recent race outcomes. In fact, bettors appeared to use the most recent race outcomes appropriately when forming probability estimates; but only when the results were in line with, what were likely to be, their expectations of BP advantage. Bettors with varying levels of expertise were shown to be subject to excessive anchoring, although greater expertise was generally associated with less excessive anchoring. The paper concludes that the manner and degree of basic anchoring in real‐world environments is complex. Copyright © 2009 John Wiley & Sons, Ltd.