bluuebunny/crossref_metadata_2025_split huggingface dataset:
Testing Bergmann's rule and the resource seasonality hypothesis in Malagasy primates using GIS‐based climate data
Authors: Kamilar Jason M. , Muldoon Kathleen M. , Lehman Shawn M. , Herrera James P. 
Published: January 2012

AbstractWe tested four major hypotheses on the ecological aspects of body mass variation in extant Malagasy strepsirrhines: thermoregulation, resource seasonality/scarcity, resource quality, and primary productivity. These biogeographic hypotheses focus on the ecological aspects of body mass variation, largely ignoring the role of phylogeny for explaining body mass variation within lineages. We tested the independent effects of climate and resource‐related variables on variation in body mass among Malagasy primates using recently developed comparative methods that account for phylogenetic history and spatial autocorrelation. We extracted data on lemur body mass and climate variables for a total of 43 species from 39 sites. Climatic data were obtained from the WorldClim database, which is based on climate data from weather stations compiled around the world. Using generalized linear models that incorporate parameters to account for phylogenetic and spatial autocorrelation, we found that diet and climate variables were weak predictors of lemur body mass. Moreover, there was a strong phylogenetic effect relative to the effects of space on lemur body mass in all models. Thus, we failed to find support for any of the four hypotheses on patterns of geography and body mass in extant strepsirrhines. Our results indicate that body mass has been conserved since early in the evolutionary history of each genus, while species diversified into different environmental niches. Our findings are in contrast to some previous studies that have suggested resource and climate related effects on body mass, though these studies have examined this question at different taxonomic and/or geographic scales. Am J Phys Anthropol, 2012. © 2012 Wiley Periodicals, Inc.
Enamel thickness in Bornean and Sumatran orangutan dentitions
Authors: Smith Tanya M. , Kupczik Kornelius , Machanda Zarin , Skinner Matthew M. , Zermeno John P. 
Published: January 2012

AbstractDental enamel thickness has received considerable attention in ecological models of the adaptive significance of primate morphology. Several authors have theorized that the degree of enamel thickness may reflect selective pressures related to the consumption of fallback foods (dietary items that may require complex processing and/or have low nutritional value) during times of preferred food scarcity. Others have speculated that enamel thickness reflects selection during mastication of foods with particular material properties (i.e., toughness and hardness). Orangutans prefer ripe fruit when available, but show interspecific and sex differences in the consumption of fallback foods (bark, leaves, and figs) and other preferred foods (certain seeds). Bornean orangutans (Pongo pygmaeus) have also been reported to masticate more mechanically demanding foods than Sumatran orangutans (Pongo abelii). To test these ecological models, we assessed two‐dimensional enamel thickness in orangutan full dentitions using established histological and virtual quantification methods. No significant differences in average enamel thickness (AET) were found between species. We found significant differences in the components of enamel thickness indices between sexes, with males showing greater enamel‐dentine junction lengths and dentine core areas, and thus relatively thinner enamel than females. Comparisons of individuals of known sex and species revealed a dentition‐wide trend for Bornean females to show greater AET than Sumatran females. Differences between small samples of males were less evident. These data provide only limited support for ecological explanations of enamel thickness patterns within great ape genera. Future studies of dietary ecology and enamel thickness should consider sex differences more systematically. Am J Phys Anthropol, 2012. © 2012 Wiley Periodicals, Inc.
Stability or variation? Patterns of lactase gene and its enhancer region distributions in Brazilian Amerindians
Authors: Friedrich Deise C. , Callegari‐Jacques Sidia M. , Petzl‐Erler M. Luiza , Tsuneto Luiza , Salzano Francisco M. , Hutz Mara H. 
Published: January 2012

AbstractLactase persistence (LP) is the phenotypic trait in which lactase secretion is maintained during adulthood. LP is due to mutations in the LCT enhancer region, located 14‐kb upstream of the gene. In Europeans, the −13910*T allele is associated with LP. In Africans this allele is rare while other mutations in this same region were related to LP. The LCT is highly polymorphic in human populations, but so far Brazilian Amerindians had not been investigated for these polymorphisms or for the presence of LP mutations. We describe the genetic diversity of the LCT region and the presence of LP enhancer mutations in four native Brazilian populations (Guarani‐Kaiowá, Guarani–Ñandeva, Kaingang, and Xavante). Twelve polymorphisms were genotyped by PCR‐based methods. The −13910*T allele varied from 0.5% in the Xavante to 7.6% in the Guarani–Ñandeva. These frequencies probably derive from European sources and they correlate with non‐native admixture proportions previously estimated for these groups. But since admixture is virtually absent in the Xavante, we suggest that the presence of the LP allele could have been determined by a de novo mutation. No other mutations in the −14 kb enhancer region were found. The LCT was highly polymorphic in the present sample showing 15 haplotypes with a heterogeneous distribution among the four Amerindian populations. This diversity could be due to drift, as indicated by the neutrality test performed. Am J Phys Anthropol, 2012. © 2012 Wiley Periodicals, Inc.
Allenes in Catalytic Asymmetric Synthesis and Natural Product Syntheses
Authors: Yu Shichao , Ma Shengming 
Published: January 2012

AbstractAllenes are the simplest class of cumulenes, with two contiguous CC bonds, and show unique physical and chemical properties. These features make allenes particularly attractive in modern organic chemistry. In this Review, attention is paid to the advances made in catalytic asymmetric synthesis and natural product syntheses based on well‐established reactions of allenes, such as propargylation, addition, cycloaddition, cycloisomerization, cyclization, etc., with or without catalysts. Their versatile reactivity, substituent‐loading ability, axial to center chirality transfer, and controllable selectivity allow access to target molecules by unique and efficient approaches. The main topics in this Review are presented with selected examples from 2003 to 2011.
Synthesis of liquefied corn barn‐based epoxy resins and their thermodynamic properties
Authors: Zhang Wenming , Zhang Yucang , Zhao Defeng 
Published: January 2012

AbstractThe liquefied corn barn‐based epoxy resin (LCBER) was synthesized through the glycidyl etherification reaction from liquefied corn barn (LCB), which has groups of bound phenol, and epichlorohydrin under alkali conditions. The average molecular weights of LCB and LCBER in various liquefaction conditions were examined. The thermodynamic properties of thermosetting resin cured by polyamide‐650 (PA‐650) were evaluated. It was found that the macromolecular chain and epoxy function of the resins would be a dominant factor for crosslinking density and properties of the cured LCBER. The cured liquefied CB‐based epoxy resin (LCBER‐30) using the corresponding LCB at 30 min (LCB‐30) as raw materials had much macromolecular exhibited higher glass‐transition and decomposition temperatures at 5% weight loss (Td), but worse shear strength in comparison with the other LCBER ones. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Effects of organic peroxide and polymer chain structure on mechanical and dynamic mechanical properties of sisal fiber reinforced polyethylene composites
Authors: Ahmad E. E. M. , Luyt A. S. 
Published: January 2012

AbstractThree types of polyethylene (PE), low‐density PE (LDPE), linear low‐density PE (LLDPE), and high‐density PE (HDPE) were used as polymer matrices to prepare untreated as well as dicumyl peroxide (DCP) treated sisal fiber composites. The effect of polymer chain structure, addition of DCP, and sisal fiber loadings on the mechanical and dynamic mechanical properties of the composite was investigated in this study. It was found that the extent of improvement in tensile properties of the composite samples varied with respect to the polymer molecular characteristics. The elongation at break for all the composites decreased significantly. Young's modulus and the tensile strength of the treated LDPE and LLDPE composites increased significantly compared with the untreated composites, whereas Young's modulus of the treated HDPE samples decreased observably compared with the untreated samples. DCP treatment, however, did not change the tensile strength of HDPE and its composites. The storage modulus results for all the PE composites correlate well with the tensile testing results. In the case of the LDPE and LLDPE samples, the curves of the mechanical loss factor (tan δ) show a clear relaxation around −18°C, which shifted to higher temperature in the treated composites, whereas for HDPE this transition was not seen. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
The role of oxidation compounds in biofilm growth on polyethylene geomembrane barriers used in landfill
Authors: Pons C. , Richaud E. , Bouchez T. , Mazeas L. , Farcas F. , Fayolle B. 
Published: January 2012

AbstractIn a model study, polyethylene was preoxidized and incubated for a period of 7 months at 40°C in two different municipal solid waste leachates. During the postexperimental analyses, specific attention was paid to the carbonyl species and carboxylic acid depletion during the environmental exposure because it is well known that carboxylic acids are believed to be a potential substrate for the development of microorganisms. The results showed that the carbonyl as well as the carboxylic acid depletion observed follows first‐order kinetics. The biofilm formation was characterized using a suite of analytical techniques, and its formation was compared with the carboxylic acid and carbonyl depletion profile. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Miscibility studies of hydroxypropyl cellulose/poly(vinyl pyrrolidone) in dilute solutions and solid state
Authors: Reddy K. Sudarsan , Prabhakar M. N. , Reddy V. Nagamaheswara , Sathyamaiah G. , Maruthi Y. , Subha M. C. S. , Chowdoji Rao K. 
Published: January 2012

AbstractThe miscibility of hydroxypropyl cellulose (HPC) and poly(vinyl pyrrolidone) (PVP) blends in aqueous solutions was studied using viscosity, ultrasonic velocity, and refractive index techniques at 30°C. The interaction parameters ΔB, μ, and α calculated from viscosity using Sun and Chee methods indicated the miscibility of this blend. This was further confirmed by ultrasonic and refractive index results. The HPC/PVP blend films are prepared by solution casting method and are analyzed by differential scanning calorimetry, X‐ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopic techniques that confirmed the complete miscibility. This miscibility is due to the strong intermolecular H‐bonding interactions between OH groups of HPC and CO groups of PVP. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
High dielectric permittivity and percolative behavior of polyvinyl alcohol/potassium dihydrogen phosphate composites
Authors: Uddin Md Jamal , Sannigrahi J. , Masud Md G. , Bhadra D. , Chaudhuri B. K. 
Published: January 2012

AbstractA new kind of anhydrous, transparent, and flexible potassium dihydrogen phosphate (KH2PO4 or KDP)/polyvinyl alcohol (PVA) composite in the form of film (0.10 mm) has been prepared by solution casting technique. KDP is well dispersed in the polymer matrix as observed from the microstructural studies. Frequency and temperature dependent dielectric properties of the composites have been studied with varying KDP concentrations. The PVA/KDP composite films exhibited extraordinarily high relative permittivity ε′ ∼ 430 (80 times higher compared with pure PVA and even higher than KDP) near the percolation threshold (ϕC = 2.5 wt % KDP) with low dielectric losses (∼ 0.15) at 1 kHz and room temperature. Such flexible, low loss and high dielectric permittivity material has enormous importance for application in devices. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Process feasibility and kinetic analysis of glass fiber‐reinforced vinyl ester/nano‐Al2O3 matrix composites for pultrusion
Authors: Sun Yun‐Yun , Chen Chin‐Hsing 
Published: January 2012

AbstractThis work presents a process developed to manufacture glass fiber‐reinforced vinyl ester (VE)/nano‐Al2O3 matrix composites by pultrusion method. The matrix prepolymer for pultrusion in this study was prepared from blends of VE, initiator (t‐butyl perbenzoate), and nano‐Al2O3. The process feasibility and kinetic analysis of the unidirectional glass fiber‐reinforced VE/nano‐Al2O3 matrix composites by pultrusion have been investigated. From the investigations of the long pot life of VE/nano‐Al2O3 matrix, the high reactivity of VE/nano‐Al2O3 matrix, and excellent fiber wet‐out of VE/nano‐Al2O3 matrix and glass fiber, it was found that the VE/nano‐Al2O3 matrix showed excellent process feasibility for pultrusion. A kinetic autocatalytic model, dα/dt = A exp(−E/RT)αm(1 − α)n, was proposed to describe the curing behavior of glass fiber‐reinforced VE/nano‐Al2O3 matrix composites. Kinetic parameters for the model were obtained from dynamic differential scanning calorimetry scans using a multiple regression technique. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Preparation and characterization of chitosan–zeolite composites
Authors: Wan Ngah W. S. , Teong L. C. , Wong C. S. , Hanafiah M. A. K. M. 
Published: January 2012

AbstractDouble crosslinked chitosan–zeolite (CZ‐2) and noncrosslinked chitosan–zeolite (CZ‐0) composites were prepared and characterized by using Fourier transform infrared (FTIR) spectrometer, surface area analyzer, scanning electron microscope coupled with energy dispersive X‐ray (SEM‐EDX) spectrometer, thermogravimetric analyzer (TGA), X‐ray diffraction analyzer (XRD) and carbon, hydrogen, nitrogen (CHN) analyzer. After crosslinking, CZ‐2 showed a reduction in surface area and CHN content in comparison to chitosan, zeolite, and CZ‐0. Crosslinking resulted in improved stability of CZ‐2 in distilled water, acetic acid and NaOH as CZ‐2 recorded the lowest percentage of swelling. XRD diffractograms confirmed the formation of composites as there was a marked difference in the peak intensity at 2θ = 19.8°. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Aggregation structure development and mechanical properties of biodegradable poly(butylene succinate‐co‐terephthalate) fibers
Authors: Luo Shengli , Li Faxue , Yu Jianyong , Cao Amin 
Published: January 2012

AbstractBiodegradable poly(butylene succinate‐co‐terephthalate)(PBST) copolyester, with 70 mol % butylene terephthalate (BT), was melt‐spun into fibers at various take‐up velocities ranging from 2.0 to 4.0 km/min. The structure development and mechanical properties of the as‐spun PBST fibers were intensively investigated via birefringence, wide angle X‐ray diffraction (WAXD) measurement, tensile test, and cyclic stretch test. With increasing the take‐up velocity, the initial tensile modulus and breaking strength of PBST fibers increased, while elongation at break decreased. These were attributed to the increasing degree of orientation and crystallinity, which were resulted from the elevating tension of spinning line at higher take‐up velocity. To elucidate the effects of soft butylene succinate (BS) unit on the tensile and elastic properties of PBST fibers, poly(butylene terephthalate) (PBT) fibers were adopted as a comparison sample. The results showed that the combination of soft BS unit and hard BT unit for PBST fibers made contribution to the lower initial modulus, higher elongation at break and better elastic recovery than those of PBT fibers. Moreover, PBST fibers were found to undergo PBT‐like crystal form transition from α‐form to β‐form crystal structure under tension load through the measurement of WAXD. A relatively wider strain region for the crystal transition of PBST fibers also endowed them with higher elastic recoverability than PBT fibers. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Phosphoric acid doped polybenzimidazole membrane for high temperature PEM fuel cell
Authors: Ergun Dilek , Devrim Yilser , Bac Nurcan , Eroglu Inci 
Published: January 2012

AbstractIn the present study, phosphoric acid doped polybenzimidazole (PBI) membranes with potential applications in high temperature PEM fuel cells were investigated. PBI was synthesized by polycondensation of 3,3′‐diaminobenzidine and isophtalic acid in polyphosphoric acid. The formation of PBI was validated by H1‐NMR and elemental analysis. PBI membranes were prepared by solution casting method and immersed in phosphoric acid in order to provide ionic conductivity. The phosphoric acid doped membranes were used to prepare membrane electrode assemblies (MEA) for PEMFC operation. Gas diffusion layer (GDL) spraying method was used to prepare the electrodes. In order to determine optimum electrode structure, the effect of electrode preparation technique on fuel cell performances was studied. Two methods were applied in which the binder differs in the catalyst ink. In the first method, 5 wt % PBI solution was used as the binder. In the second method, polyvinylidene fluoride (PVDF) was used in addition to PBI as the binder in the catalyst ink. The MEA were tested in a single cell operating at 100°C without need for humidification of reactant gases. The observed maximum power output was increased considerably from 0.015 to 0.072 W/cm2 at 150°C when the binder of the catalyst was changed from PBI to PBI and PVDF mixture (PVDF : PBI = 3 : 1). A single cell was operated up to 160°C and the power outputs of 0.032 and 0.063 W/cm2 were obtained at operating temperatures of 125 and 160°C, respectively. The PVDF : PBI ratio was 1 : 3 in the catalyst ink at both temperatures. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Electropolymerization and characterization of 3,4‐ethylenedioxy thiophene on glassy carbon electrode and study of ions transport of the polymer during redox process
Authors: Moradi Atefeh , Emamgolizadeh Abbas , Omrani Abdollah , Rostami Abbas Ali. 
Published: January 2012

AbstractPoly(3,4‐ethylenedioxythiophene) (PEDOTh) films were deposited on glassy carbon (GC) electrodes from organic electrolytes containing the monomer in a solution of acetonitrile (AN). The effect of the supporting electrolyte used during electropolymerization, on the redox behavior, surface morphology, and degree of crystallinity of the films has been investigated by FTIR, cyclic voltammetry, and scanning electron microscopy (SEM) techniques. The use of LiPF6 leads to a higher electropolymerization efficiency and an increase of electroactivity and crystallinity of the polymer. On the basis of voltammetric studies of the Nernst and Butler–Volmer equations, we concluded that BF4−, ClO4−, and PF6− anions are the mobile species during the redox process of the PEDOTh films. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Structure development and melt viscoelastic properties of PE/organoclay nanocomposite blown films
Authors: Abdolrasouli Mehdi H. , Behzadfar Ehsan , Nazockdast Hossein , Sharif Farhad 
Published: January 2012

AbstractThe effects of compatibilizer and the type of polyethylene (PE) matrix on structure development of PE/organoclay nanocomposite samples were investigated by means of X‐ray diffraction technique and transmission electron microscopy in conjunction with melt viscoelastic measurements. It was shown that the presence of compatibilizer plays a key role in determining the extent of intercalation and resulting structure development in both linear low‐density polyethylene (LLDPE) and low‐density polyethylene (LDPE). The LLDPE/organoclay nanocomposite samples exhibited a pronounced low‐frequency nonterminal storage modulus whose values were found to be greater than those of LDPE/organoclay nanocomposite samples. The percentage increase in storage modulus values for the compatibilized LLDPE/organoclay nanocomposite sample compared to the virgin LLDPE sample was 1080, while the percentage increase in storage modulus values for the compatibilized LDPE/organoclay nanocomposite sample compared to the virgin LDPE sample was 200, at frequency 0.1 s−1. The melt viscoelastic measurements performed on the nanocomposite blown film samples indicated that at higher draw‐down ratio the organoclay platelets and/or tactoids were aligned in the flow direction. Comparing the melt viscoelastic results obtained for annealed and unannealed nanocomposite blown film samples, it was demonstrated that the reorientation of the induced organoclay alignment, which led to network structure formation in the amorphous phase of PE, is very slow, and the time required to complete the reorientation was found to be longer than 3 h at annealing temperature (100°C). © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Enhanced conductivity and fluorescence of polyaniline doped with Eu3+, Tb3+, and Y3+ ions
Authors: Zhang Jiali , Wang Hao , Yang Shimei , Wang Shaohui , Yang Shaoming 
Published: January 2012

AbstractThe doped polyaniline (PANI) with rare earth ions, which exhibits an increasing conductivity and strongly enhanced fluorescence emission, was prepared by dispersing PANI powder suspension in acetonitrile solution containing rare earth ions according to different mass ratios of rare earth ions to PANI at room temperature. The structure of the doped PANI was characterized by the spectra of FTIR, Raman, UV‐vis, and XRD. Red‐shifted change for the quinoid and benzenoid stretching vibration is observed in IR and Raman spectra after doping rare earth cations, and UV‐vis absorption peak also presents a red‐shift, indicating that the doped PANI possesses a better delocalization of electrons along the mainchain backbone. The experimental data show that the electrical and optical behaviors of PANI strongly depend on the species of rare earth cations and their concentration. It is found that enhancing fluorescence for the doped PANI is observed by comparing with emeraldine base (EB). Moreover, the conductivity of the protonated PANI samples doped with Eu3+, Tb3+, and Y3+ ions, increases from 2.1 × 10−4 to 3.33 S cm−1, 1.50 × 10−1 S cm−1 and 2.26 × 10−1 S cm−1. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Covalent‐ionically crosslinked sulfonated poly(arylene ether sulfone)s bearing quinoxaline crosslinkages as proton exchange membranes
Authors: Chen Pei , Chen Xinbing , An Zhongwei 
Published: January 2012

AbstractCrosslinkable sulfonated poly(arylene ether sulfone)s (SPAESs) were synthesized by copolymerization of 4,4′‐biphenol with 2,6‐difluorobenzil, 4,4′‐difluorodiphenyl sulfone, and 3,3′‐disulfonated‐4,4′‐difluorodiphenyl sulfone disodium salt. The corresponding covalent‐ionically crosslinked SPAESs were prepared via the cyclocondensation reaction of benzil moieties in polymer chain with 3,3′‐diaminobenzidine. The crosslinking significantly improved the membrane performance, that is, the crosslinked membranes had the lower membrane dimensional swelling, lower methanol permeability, and higher oxidative stability than the corresponding precursor membranes, with keeping the reasonably high proton conductivity. The crosslinked membrane (CS5) with measured ion exchange capacity of 1.47 meq g−1 showed a reasonably high proton conductivity of 112 mS cm−1 with water uptake of 42 wt % at 80°C, and exhibited a low methanol permeability of 2.1 × 10−7 cm2 s−1 for 32 wt % methanol solution at 25°C. The crosslinked SPAES membranes have potential for PEFC and DMFCs. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012