bluuebunny/crossref_metadata_2025 huggingface dataset:
The Impact of Polymer Regioregularity on Charge Transport and Efficiency of P3HT:PCBM Photovoltaic Devices
Authors: Mauer Ralf , Kastler Marcel , Laquai Frédéric
Published: May 2010

The charge transport in pristine poly(3‐hexylthiophene) (P3HT) films and in photovoltaic blends of P3HT with [6,6]‐phenyl C61 butyric acid methyl ester (PCBM) is investigated to study the influence of charge‐carrier transport on photovoltaic efficiency. The field‐ and temperature dependence of the charge‐carrier mobility in P3HT of three different regioregularities, namely, regiorandom, regioregular with medium regioregularity, and regioregular with very high regioregularity are investigated by the time‐of‐flight technique. While medium and very high regioregularity polymers show the typical absorption features of ordered lamellar structures of P3HT in the solid state even without previous annealing, films of regiorandom P3HT are very disordered as indicated by their broad and featureless absorption. This structural difference in the solid state coincides with partially non‐dispersive transport and hole mobilities µh of around 10−4 and 10−5 cm2 V−1 s−1 for the high and medium regioregularity P3HT, respectively, and a slow and dispersive charge transport for the regiorandom P3HT. Upon blending the regioregular polymers with PCBM, the hole mobilities are typically reduced by one order of magnitude, but they do not significantly change upon additional post‐spincasting annealing. Only in the case of P3HT with high regioregularity are the electron mobilities similar to the hole mobilities and the charge transport is, thus, balanced. Nonetheless, devices prepared from both materials exhibit similar power conversion efficiencies of 2.5%, indicating that very high regioregularity may not substantially improve order and charge‐carrier transport in P3HT:PCBM and does not lead to significant improvements in the power‐conversion efficiency of photovoltaic devices.
A Three‐Dimensional Gold‐Decorated Nanoporous Copper Core–Shell Composite for Electrocatalysis and Nonenzymatic Biosensing
Authors: Chen L.Y. , Fujita T. , Ding Y. , Chen M. W.
Published: May 2010

Bimetallic core–shell nanostructures have attracted increasing attention due to their low material costs along with enhanced chemico‐physical properties in comparison with their monometallic counterparts. Here, a novel gold‐decorated nanoporous copper (Au@NPC) core–shell composite fabricated by a facile in situ hydrometallurgy approach is reported. Thin gold shells with a controllable thickness are homogeneously deposited onto the internal surfaces of 3D nanoporous copper via a spontaneous displacement reaction while nanoporous copper is utilized as a reduction agent as well as 3D template and substrate. The resulting inexpensive core–shell nanostructure exhibits significant electrocatalytic activity for the oxidation of methanol and high non‐enzymatic sensitivity in detecting glucose.
Export market participation, spillovers, and foreign direct investment in Australian food manufacturing
Authors: Phillips Shauna , Ahmadi‐Esfahani Fredoun Z.
Published: May 2010

Generating a more outward looking sector has been one of the principal aims of agrifood policy in Australia for the past two decades. Australia's proximity to fast‐growing economies of East Asia has been seen as a major source for export growth. Over the same time span, there has been an increase in foreign ownership in the food sector. Using a firm‐level data set for 2005, we characterize the probability that a firm participates in exporting by a set of firm characteristics, including foreign ownership and spillovers from foreign‐owned firms, and find that foreign ownership neither increases nor decreases the probability that a firm will be involved in exporting. [EconLit citations: Q170, Q130]. © 2010 Wiley Periodicals, Inc.
DEM simulation of a 3D vertical vibratory screening process: The study of a simulated woven‐mesh structure
Authors: Tung Kuo Lun , Chang Ting Hsiang , Lin Yi‐Feng , Chyang Chien‐Song
Published: May 2010

A discrete‐element method (DEM) was applied to analyze the complicated phenomena of granular screening using different plate‐, bead‐, and woven‐mesh structures. In the past, mesh structures have often been simplified as plate or bead structures in screening‐process simulations, resulting in large differences between the simulated and experimental sieving rate. Here, a mesh‐type, 3D woven structure was accurately modeled, and the simulated sieving process yielded results more closely resembling the experimental process. The woven‐mesh model constructed of sine and cosine functions was also used to assess the effect of the structures on the sieving rate and mesh‐blocking phenomena, i.e., cohesionless particles plugging the mesh. By monitoring the in situ blocking conditions in the discrete‐element method simulation, cohesionless particles with diameters of 1.1w (where w is the size of the aperture) were found to block the most mesh apertures. The large difference in sieving rates observed when separating particles with sizes of 0.7w and 1.1w and those of 0.9w and 1.1w resulted from the differing degree of freedom for the smaller particles to move to the bottom of the bed. The 0.7w particles were more able to move downward in the bed and be sieved out, leading to a higher sieving rate as compared to those with 0.9w diameters. The significant factors and phenomena of the sieving process, such as particle–mesh and particle–particle interactions, instantaneous mesh‐blocking, and the intrinsic motion of the granular bed, which cannot be observed experimentally, can be modeled by the DEM simulation using our 3D woven‐mesh model. © 2010 American Institute of Chemical Engineers AIChE J, 2011
Model‐based measurement of particle size distributions in layering granulation processes
Authors: Bück Andreas , Peglow Mirko , Tsotsas Evangelos , Mangold Michael , Kienle Achim
Published: May 2010

In this work, we present a method for the online estimation of particle size distributions in layering granulation processes using a methodology known as model‐based measurement or state estimation. After presenting the necessary model equations for two practically relevant processes it is investigated which quantities of the processes have to be measured to estimate the size distribution. For the different processes square‐root unscented Kalman filters (SR‐UKF) are designed and tested in simulations to demonstrate the feasibility of this approach. © 2010 American Institute of Chemical Engineers AIChE J, 2011
Secular trend in age at menarche in indigenous and nonindigenous women in Chile
Authors: Ossa X.M. , Munoz S. , Amigo H. , Bangdiwala S.I.
Published: May 2010

Objectives:

To estimate the secular trend in age at menarche, comparing indigenous and nonindigenous women, and its relationship with socio‐demographic, family and nutritional factors.

Methods:

A study (historical cohorts) of 688 indigenous and nonindigenous women, divided into four birth cohorts (1960–69, 1970–79, 1980–89, and 1990–96) in an area in central southern Chile was carried out. Data and measurements were collected by health professionals using a previously validated questionnaire. Age at menarche was self‐reported (recall). Adjusted differences among cohorts were estimated using a multivariate regression model.

Results:

A secular trend (P < 0.001) in age at menarche was found in both ethnic groups, with no significant differences between them (P > 0.05). In an adjusted model, a reduction in age at menarche was estimated at 3.7 months per decade between 1960 and 1990. This trend was moderated by higher socio‐economic level, smaller number of siblings, and cohabitation with a single parent during infancy.

Conclusions:

The trend has occurred in a steady progression over time in indigenous women, whereas in nonindigenous women, it was slow initially but has accelerated in recent years. Nonindigenous women have maintained a slightly lower age of menarche than their indigenous counterparts. Am. J. Hum. Biol. 22:688‐694, 2010. © 2010 Wiley‐Liss, Inc.
Comparison of body fat estimates using 3D digital laser scans, direct manual anthropometry, and DXA in men
Authors: Garlie Todd N. , Obusek John P. , Corner Brian D. , Zambraski Edward J.
Published: May 2010

Objectives:

The purpose of this study was to assess the feasibility of utilizing three dimensional whole body laser surface scanning (3DS) to obtain specific anthropometric measurements to estimate percent body fat (BF).

Methods:

Percent BF estimates from 37 male volunteers, of age 18–62 yr, were determined by inputting manual anthropometric (MA) and 3DS anthropometric measurements into the current Army BF prediction equation for males. The results were compared with each other and to BF values from Dual Energy X‐ray Absorptiometry (DXA), employed as a reference method.

Results:

Mean percent BF estimates (±SD) derived from MA, 3DS and from DXA were 18.4(±3.8), 18.8(±3.9), and 18.9(±4.7), respectively. Analysis of Variance tests revealed no statistical difference between the mean values. Correlation analysis comparing MA and 3DS derived percent BF estimates to each other and to those measured by DXA revealed moderate to strong Pearson correlation coefficients (r), small to moderate standard errors of the estimate (SEE), and were statistically significant (p< 0.05).

Conclusions:

Correlation coefficients and SEE results for this sample were: (1) DXA vs 3DS;r= 0.74, SEE = 3.2, (2) MA vs DXA;r= 0.82, SEE = 2.8, and (3) MA vs 3DS;r= 0.96, SEE = 1.0. Lin's concordance analysis, including Bland‐Altman limits of agreement (LOA), revealed statistically significant measurement agreement among the three measurement modalities (p< 0.05). The application of 3DS scanning to estimate percent BF from commonly used anthropometric measurements are in close agreement with BF estimates derived from analogous MA measurements and from DXA scanning. Am. J. Hum. Biol. 22:695‐701, 2010. Published 2010Wiley‐Liss, Inc.
Variation in dental wear and tooth loss among known‐aged, older ring‐tailed lemurs (Lemur catta): a comparison between wild and captive individuals
Authors: Cuozzo Frank P. , Sauther Michelle L. , Gould Lisa , Sussman Robert W. , Villers Lynne M. , Lent Cheryl
Published: May 2010

Tooth wear is generally an age‐related phenomenon, often assumed to occur at similar rates within populations of primates and other mammals, and has been suggested as a correlate of reduced offspring survival among wild lemurs. Few long‐term wild studies have combined detailed study of primate behavior and ecology with dental analyses. Here, we present data on dental wear and tooth loss in older (>10 years old) wild and captive ring‐tailed lemurs (Lemur catta). Among older ring‐tailed lemurs at the Beza Mahafaly Special Reserve (BMSR), Madagascar (n=6), the percentage of severe dental wear and tooth loss ranges from 6 to 50%. Among these six individuals, the oldest (19 years old) exhibits the second lowest frequency of tooth loss (14%). The majority of captive lemurs at the Indianapolis Zoo (n=7) are older than the oldest BMSR lemur, yet display significantly less overall tooth wear for 19 of 36 tooth positions, with only two individuals exhibiting antemortem tooth loss. Among the captive lemurs, only one lemur (a nearly 29 year old male) has lost more than one tooth. This individual is only missing anterior teeth, in contrast to lemurs at BMSR, where the majority of lost teeth are postcanine teeth associated with processing specific fallback foods. Postcanine teeth also show significantly more overall wear at BMSR than in the captive sample. At BMSR, degree of severe wear and tooth loss varies in same aged, older individuals, likely reflecting differences in microhabitat, and thus the availability and use of different foods. This pattern becomes apparent before “old age,” as seen in individuals as young as 7 years. Among the four “older” female lemurs at BMSR, severe wear and/or tooth loss do not predict offspring survival. Am. J. Primatol. 72:1026–1037, 2010. © 2010 Wiley‐Liss, Inc.
The Chehr Abad “Salt men” and the isotopic ecology of humans in ancient Iran
Authors: Ramaroli V. , Hamilton J. , Ditchfield P. , Fazeli H. , Aali A. , Coningham R.A.E. , Pollard A.M.
Published: May 2010

We have carried out isotopic analysis (δ13C and δ15N) on five salt‐preserved bodies from the salt mine at Chehr Abad, Iran, dating from the 4th C. BC through to the 4th C. AD. In an attempt to identify the geographical origins of these people, we have analyzed over a hundred archeological bone samples from various archeological sites in Iran. From the faunal remains, we observe that the entire ecosystem appears to be enriched in 15N, which we suggest is due to the semi‐arid nature of the region. We have also observed a number of cattle remains from one site (Nargas Tepe) which have a significant C4 component to their diet from the 4th millennium BC. By combining our data with those published by [Bocherens et al.: Environ Archaeol 5 (2000) 1–19; Bocherens et al.: J Arch Sci 33 (2006) 253–264], we suggest that two of the “mummies” may have come from the Tehran/Qazvin Plain region (i.e., relatively local to the salt mine), and a further two appear on isotopic grounds to have come from the northeast of Iran or the Turkmenistan steppes. The fifth (no. 4), the best preserved, appears to have come from further afield. Collectively, these mummies and their contexts augment our knowledge of social mobility and technical innovation in Iran during the Achaemenid period. Am J Phys Anthropol 143:343‐354, 2010. © 2010 Wiley‐Liss, Inc.
Determination of sex from the hyoid bone
Authors: Kindschuh Sarah C. , Dupras Tosha L. , Cowgill Libby W.
Published: May 2010

This article explores size differences related to sex in the hyoid bones from the Robert J. Terry Anatomical Collection. A series of measurements were taken from 398 hyoids, both fused and unfused. The inclusion of unfused hyoids in the study provides the opportunity to investigate previously unknown size differences between sexes as well as to determine their utility in determining sex. Two‐way ANOVA was used to explore differences in hyoid size as related to ancestry and sex. Discriminant function analysis was employed to test the ability of the hyoids to be classified by sex. Six discriminant function equations ranging in accuracy from 82% to 85% are provided, each of which is more accurate than many of the discriminant functions developed in past hyoid research, are simple to use, and can be used to estimate the sex of a hyoid regardless of its state of fusion. In addition to providing further information about the morphological form of the hyoid, these analyses provide a method that can be easily employed to assess sex of the individual from the hyoid bone. Am J Phys Anthropol 143:279–284, 2010. © 2010 Wiley‐Liss, Inc.
Estimating body mass in subadult human skeletons
Authors: Robbins Gwen , Sciulli Paul W. , Blatt Samantha H.
Published: May 2010

Methods for estimating body mass from the human skeleton are often required for research in biological or forensic anthropology. There are currently only two methods for estimating body mass in subadults: the width of the distal femur metaphysis is useful for individuals 1–12 years of age and the femoral head is useful for older subadults. This article provides age‐structured formulas for estimating subadult body mass using midshaft femur cross‐sectional geometry (polar second moments of area). The formulas were developed using data from the Denver Growth Study and their accuracy was examined using an independent sample from Franklin County, Ohio. Body mass estimates from the midshaft were compared with estimates from the width of the distal metaphysis of the femur. Results indicate that accuracy and bias of estimates from the midshaft and the distal end of the femur are similar for this contemporary cadaver sample. While clinical research has demonstrated that body mass is one principle factor shaping cross‐sectional geometry of the subadult midshaft femur, clearly other biomechanical forces, such as activity level, also play a role. Thus formulas for estimating body mass from femoral measurements should be tested on subadult populations from diverse ecological and cultural circumstances to better understand the relationship between body mass, activity, diet, and morphology during ontogeny. Am J Phys Anthropol 143:146–150, 2010. © 2010 Wiley‐Liss, Inc.
Comparison between morphological and genetic data to estimate biological relationship: The case of the Egyin Gol necropolis (Mongolia)
Authors: Ricaut François‐X. , Auriol Vincent , von Cramon‐Taubadel Noreen , Keyser Christine , Murail Pascal , Ludes Bertrand , Crubézy Eric
Published: May 2010

Osseous and dental nonmetric (discrete) traits have long been used to assess population variability and affinity in anthropological and archaeological contexts. However, the full extent to which nonmetric traits can reliably be used as a proxy for genetic data when assessing close or familial relationships is currently poorly understood. This study represents the unique opportunity to directly compare genetic and nonmetric data for the same individuals excavated from the Egyin Gol necropolis, Mongolia. These data were analyzed to consider the general efficacy of nonmetric traits for detecting familial groupings in the absence of available genetic data. The results showed that the Egyin Gol population is quite homogenous both metrically and genetically confirming a previous suggestion that the same people occupied the necropolis throughout the five centuries of its existence. Kinship analysis detected the presence of potential family burials in the necropolis. Moreover, individuals buried in one sector of the necropolis were differentiated from other sectors on the basis of nonmetric data. This separation is likely due to an outside Turkish influence in the paternal line, as indicated by the results of Y‐chromosome analysis. Affinity matrices based on nonmetric and genetic data were correlated demonstrating the potential of nonmetric traits for detecting relationships in the absence of genetic data. However, the strengths of the correlations were relatively low, cautioning against the use of nonmetric traits when the resolution of the familial relationships is low. Am J Phys Anthropol 143:355‐364, 2010. © 2010 Wiley‐Liss, Inc.
The biomechanics of leaping in gibbons
Authors: Channon A.J. , Crompton R.H. , Günther M.M. , D'Août K. , Vereecke E.E.
Published: May 2010

Gibbons are skilled brachiators but they are also highly capable leapers, crossing distances in excess of 10 m in the wild. Despite this impressive performance capability, no detailed biomechanical studies of leaping in gibbons have been undertaken to date. We measured ground reaction forces and derived kinematic parameters from high‐speed videos during gibbon leaps in a captive zoo environment. We identified four distinct leap types defined by the number of feet used during take‐off and the orientation of the trunk, orthograde single‐footed, orthograde two‐footed, orthograde squat, and pronograde single‐footed leaps. The center of mass trajectories of three of the four leap types were broadly similar, with the pronograde single‐footed leaps exhibiting less vertical displacement of the center of mass than the other three types. Mechanical energy at take‐off was similar in all four leap types. The ratio of kinetic energy to mechanical energy was highest in pronograde single‐footed leaps and similar in the other three leap types. The highest mechanical work and power were generated during orthograde squat leaps. Take‐off angle decreased with take‐off velocity and the hind limbs showed a proximal to distal extension sequence during take‐off. In the forelimbs, the shoulder joints were always flexed at take‐off, while the kinematics of the distal joints (elbow and wrist joints) were variable between leaps. It is possible that gibbons may utilize more metabolically expensive orthograde squat leaps when a safe landing is uncertain, while more rapid (less expensive) pronograde single‐footed leaps might be used during bouts of rapid locomotion when a safe landing is more certain. Am J Phys Anthropol 143:403‐416, 2010. © 2010 Wiley‐Liss, Inc.
Sexual dimorphism in chin shape: Implications for adaptive hypotheses
Authors: Thayer Zaneta M. , Dobson Seth D.
Published: May 2010

The chin, or mentum osseum, is one of the most distinctive anatomical traits of modern humans. A variety of hypotheses for the adaptive value of the chin have been proposed, ranging from mechanical stress resistance to sexual selection via mate choice. While the sexual selection hypothesis predicts dimorphism in chin shape, most biomechanical hypotheses preclude it. Therefore determining the presence or absence of significant sexual dimorphism in chin shape provides a useful method for differentiating between various adaptive hypotheses; however, this has yet to be done due to a lack of quantitative data on chin shape. The goals of this study are therefore: (1) to introduce a new method for quantifying chin shape and (2) to determine the presence or absence of sexual dimorphism in chin shape in a diverse sample of modern humans. Samples were drawn from recent human skeletal collections representing nine geographic regions. Outlines of mentum osseum contours were quantified using elliptical Fourier function analysis (EFFA). Fourier coefficients were analyzed using principal components analysis (PCA). Sexual dimorphism in chin shape was assessed using PC loadings in the pooled geographic sample, and statistically significant differences were found. These findings provide the first quantitative, morphologically based evidence in support of adaptive hypotheses that predict dimorphism in chin shape, including the sexual selection hypothesis. Am J Phys Anthropol 143:417‐425, 2010. © 2010 Wiley‐Liss, Inc.
Interaction of Metal Complexes with G‐Quadruplex DNA
Authors: Georgiades Savvas N. , Abd Karim Nurul H. , Suntharalingam Kogularamanan , Vilar Ramon
Published: May 2010

Guanine‐rich sequences of DNA can assemble into tetrastranded structures known as G‐quadruplexes. It has been suggested that these secondary DNA structures could be involved in the regulation of several key biological processes. In the human genome, guanine‐rich sequences with the potential to form G‐quadruplexes exist in the telomere as well as in promoter regions of certain oncogenes. The identification of these sequences as novel targets for the development of anticancer drugs has sparked great interest in the design of molecules that can interact with quadruplex DNA. While most reported quadruplex DNA binders are based on purely organic templates, numerous metal complexes have more recently been shown to interact effectively with this DNA secondary structure. This Review provides an overview of the important roles that metal complexes can play as quadruplex DNA binding molecules, highlighting the unique properties metals can confer to these molecules.
Synthesis, characterization and biological studies of alkenyl‐substituted titanocene(IV) carboxylate complexes
Authors: Kaluđerović Goran N. , Tayurskaya Valentina , Paschke Reinhard , Prashar Sanjiv , Fajardo Mariano , Gómez‐Ruiz Santiago
Published: May 2010

The carboxylate compounds [Ti(η5‐C5H5)(η5‐C5H4{CMe2(CH2CH2CHCH2)})(O2CCH2SXyl)2] (2; Xyl = 3,5‐Me2C6H3) and [Ti(η5‐C5H5)(η5‐C5H4{CMe2(CH2CH2CHCH2)})(O2CCH2SMesl)2] (3; Mes 1 = 2,4,6‐Me3C6H2) were synthesized by the reaction of [Ti(η5‐C5H5)(η5‐C5H4{CMe2(CH2CH2CHCH2)})Cl2] (1) with 2 equivalents of xylylthioacetic acid or mesitylthioacetic acid, respectively. Compounds 2 and 3 were characterized by spectroscopic methods. The cytotoxic activity of 1–3 was tested against human tumor cell lines from four different histogenic origins—8505C (anaplastic thyroid cancer), DLD‐1 (colon cancer) and the cisplatin sensitive A253 (head and neck cancer) and A549 (lung carcinoma)—and compared with those of the reference complex [Ti(η5‐C5H5)2Cl2] (R1) and cisplatin. Surprisingly, the cytotoxic activities of the carboxylate derivatives were lower than those of their corresponding dichloride analogue (1). However, complexes 1–3 were more active than titanocene dichloride against all the studied cells with the exception of complex 2 against A253 and A549 cell lines. DNA‐interaction tests were also carried out. Solutions of all the studied complexes were treated with different concentrations of fish sperm DNA, observing modifications of the UV spectra with intrinsic binding constants of 2.99 × 105, 2.45 × 105, and 2.35 × 105 M−1 for 1–3. Structural studies based on density functional theory calculations of 2 and 3 were also carried out. Copyright © 2010 John Wiley & Sons, Ltd.
Novel ferrocenyl phosphonate derivatives. Inhibition of serine hydrolases by ferrocene azaphosphonates
Authors: Rudolf Bogna , Salmain Michèle , Haquette Pierre , Stachowicz Marcin , Woźniak Krzysztof
Published: May 2010

Owing to their unique properties, ferrocene compounds are gaining increasing interest for biological applications, particularly as enzyme inhibitors. Phosphonate derivatives including a ferrocenyl moiety were synthesized by reaction of dimethyl‐ and diphenylphosphite with ferrocenyl methyl maleimide. The ferrocenyl diphenyl phosphonate complex was characterized by X‐ray diffraction. The ability of these organometallic compounds to inhibit the enzymatic activity of the serine esterases acetyl‐ and butyrylcholinesterase was investigated. It appeared that the new ferrocenyl phosphonates inhibited both enzymes by competitive, mixed or non competitve mechanisms with inhibition constants in the range 35–1000 µM. Both compounds also behave as slow time‐dependent inactivators of butyrylcholinesterase. The presence of the ferrocenyl entity seems then to have a dramatic effect on the biochemical behavior of the systems. Copyright © 2010 John Wiley & Sons, Ltd.
Synthesis, characterization and in vitro biological activity of cobalt(II), copper(II) and zinc(II) Schiff base complexes derived from salicylaldehyde and D,L‐selenomethionine
Authors: Ran Xueguang , Wang Lingyun , Cao Derong , Lin Yingcai , Hao Jie
Published: May 2010

New cobalt(II), copper(II) and zinc(II) complexes of Schiff base derived from D,L‐selenomethionine and salicylaldehyde were synthesized and characterized by elemental analysis, IR, electronic spectra, conductance measurements, magnetic measurements and biological activity. The analytical data showed that the Schiff base ligand acts as tridentate towards divalent metal ions (cobalt, copper, zinc) via the azomethine‐N, carboxylate oxygen and phenolato oxygen by a stoichiometric reaction of M:L (1:1) to form metal complexes [ML(H2O)], where L is the Schiff base ligand derived from D,L‐selenomethionine and salicylaldehyde and M = Co(II), Cu(II) and Zn(II). 1H NMR spectral data of the ligand and Zn(II) complex agree with proposed structures. The conductivity values between 12.87 and 15.63 S cm2 mol−1 in DMF imply the presence of non‐electrolyte species. Antibacterial and antifungal results indicate that the metal complexes are more active than the ligand. Copyright © 2010 John Wiley & Sons, Ltd.
Thermal properties of low loss PTFE‐CeO2dielectric ceramic composites for microwave substrate applications
Authors: Anjana P. S. , Uma S. , Philip J. , Sebastian M. T.
Published: May 2010

Polytetrafluroethylene (PTFE) composites filled with CeO2were prepared by powder processing technique. The PTFE is used as the matrix and the loading fraction of CeO2in the composite varied up to 0.6 volume fraction. The thermal conductivity and coefficient of thermal expansion were studied in relation to filler concentration. The thermal conductivity increased and coefficient of thermal expansion decreased with increase in CeO2content. For 0.6 volume fraction loading of the ceramic, the composite has a thermal conductivity of 3.1 W/m°C and coefficient of thermal expansion 19.6 ppm/°C. Different theoretical approaches have been employed to predict the effective thermal conductivity and coefficient of thermal expansion of composite systems and the results were compared with the experimental data. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Zein‐based ultrathin fibers containing ceramic nanofillers obtained by electrospinning. I. Morphology and thermal properties
Authors: Torres‐Giner Sergio , Lagaron Jose M.
Published: May 2010

This work presents the first results on the development and characterization of novel nanobiocomposite fibers prepared by electrospinning of zein/clay mixtures (from 99/1 to 75/25 wt/wt) from ethanol‐based solutions. To do so, commercial ceramic materials of different nature, such as organomodified and unmodified mica, kaolinite, montmorillonite, and zeolite were employed and compared. A significant decrease in fiber diameter was observed as the clay fraction increased in the hybrid material. The highest clay contents also produced fibers but with extended beaded regions. All fillers nanodispersed well in the fibers at low loadings but unmodified mica particles were also seen excluded from the fibers, most likely due to excessive size. Surprisingly, the ceramic laminar structures, i.e. the phyllosilicates, were all seen to embed within the ultrathin fibers in what appears as an unreported rolled morphology due to the extensional forces generated by the electrospinning process. Electrospun nanobiocomposite fibers with optimal ceramic nanoparticle contents are currently investigated as an adequate procedure to prepare naturally occurring composite additives, coatings, and interlayers with enhanced performance in terms of mechanical, thermal, barrier, and control release properties for packaging, active packaging, biomedical, and pharmaceutical applications. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Repeated impacts tests and nanoindentation as complementary tools for mechanical characterization of polymer‐coated particles
Authors: Perfetti G. , Arfsten J. , Kwade A. , Wildeboer W. J. , Meesters G. M. H.
Published: May 2010

Polymer‐coated particles have been produced by applying two grades of hydroxypropyl methylcellulose and one grade of polyvinyl alcohol onto sodium benzoate Purox‐S core particles by using top‐spray fluid bed coater and then stored under two different conditions, namely ambient conditions (23°C, 55% RH) and in the freezer (−18°C, 25% RH). Surface morphology has been firstly analyzed using scanning electron microscope and atomic force microscope. Resistance to attrition and viscoelastic properties have been measured by repeated impact tester (RIT) and nanoindentation, respectively. The resistance to attrition have been discussed as function of type of coating materials, breakage mechanisms, and storage temperature, and then compared with uncoated Purox‐S. The storage conditions is not influencing the morphology, whereas is strongly affecting the resistance to attrition. Coated particles stored at −18°C were found to be more resistant to attrition than ones stored at room conditions. Such differences negligible at low energies (low numbers of impacts) increase as soon as the number of impacts and the energy rise. The improvement in the resistance to attrition was related to the plasticizing effect of water content. Displacement, storage modulus (E′), loss modulus (E″), and damping factor (tan δ) have been measured for all coated particles. Quasistatic and dynamic nanoindentation were found to agree very well with each other. Comparison of the nanoindentation results and the RIT results showed that tan δ, as measure of viscoelasticity and flexibility of the polymeric coating material, is related to the attrition behavior. It was found, in fact, that a higher tan δ gives more resistance to attrition. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
The mesh disturbance effects in a low‐temperature cascade arc torch for surface modification of low density polyethylene
Authors: Gilliam Mary , Ritts Andrew , Yu Qingsong
Published: May 2010

A stainless steel mesh was placed in a low‐temperature cascade arc torch (LTCAT) to study its disturbance effects on the plasmas and on the surface modification of low density polyethylene (LDPE). It was found that the photoemitting species were deflected by the screen and only faint glow was observed after the mesh. Optical emission spectroscopy examination indicated that the amount of electronically excited species in the plasma was greatly reduced after passing through the mesh. Grounding the mesh altered the nature of the discharge and a greater intensity of O emission was observed in Ar LTCAT + O2 discharge, which indicated greater energy transfer to the oxygen. Although a decrease in surface damage was observed on the treated LDPE samples by placement of the mesh in the Ar LTCAT discharges, the wettability achieved was also greatly reduced. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Modification of poly acrylic acid using calix[4]arene derivative for the adsorption of toxic heavy metals
Authors: Hajipour Abdol Reza , Habibi Sakineh , Ruoho Arnold E.
Published: May 2010

Poly acrylic acid (PAA) was grafted with p‐t‐butyl calix[4]arene diamine (distal cone) (2) to adsorb toxic heavy metal and alkali metal cations. The grafting method includes the amidation reaction of PAA with calixarene diamine derivative 2 which was carried out in N,N‐dimethylformamide (DMF) and N–methyl‐2‐pyrrolidone (NMP) as solvents. The modified PAAs (PAA‐C1 and PAA‐C2) were characterized by FTIR, 1H‐NMR, thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). PAA‐C1 and PAA‐C2 were used to evaluate the sorption properties of some toxic heavy metal cations (Co2+, Cu2+, Cd2+, Hg2+), alkali metal cations (Na+, K+, Cs+), and Ag+. Results showed that the modified PAAs were good sorbents for heavy metal and alkali metal cations. The main goal of this project is to design hydrophobically modified PAA that is suitable for ion selective membranes and chemical sensor devices for adsorption of toxic heavy metals. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Crystal structure, curing kinetics, and thermal properties of bisphenol fluorene epoxy resin
Authors: Xiong Yuanqin , Liu Hanping , Ou Encai , Zeng Xiaoliang , Zhou Wei , Xu Weijian
Published: May 2010

Diglycidyl ether of 9,9‐bis(4‐hydroxyphenyl) fluorene (DGEBF) monomer was successfully synthesized and characterized in detail. The crystal structure of DGEBF was measured by single‐crystal X‐ray diffraction analysis. Curing kinetics of DGEBF with 4,4‐diaminodiphenyl sulfone (DDS), thermal properties, and decomposition kinetics were investigated using nonisothermal differential scanning calorimetry (DSC) according to Kissinger, Ozawa and Crane methods. The glass transition temperature (Tg), thermal properties of cured polymer were estimated by DSC, dynamic mechanical analysis, and thermogravimetric analyses. Epoxy value of DGEBF monomer up to theoretical value leads to higher crosslink density of cured polymers. The cured DGEBF/DDS system exhibited obvious higher Tg and better thermal stability compared to those of DGEBF/diamine systems reported previously. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Polymerization of linseed oil with phenolic resins
Authors: Çaylı Gökhan , Küsefoğlu Selim
Published: May 2010

In this study, linseed oil was directly polymerized with different oil soluble resoles. p‐Ethyl (PEP), p‐tertiary butyl (PTB), p‐tertiary octyl (PTO), and p‐phenyl (PPP) phenols were separately reacted with formaldehyde to give linseed oil soluble resoles. These were then reacted with linseed oil to give transparent rubbery polymers. A model reaction was performed with methyl oleate and PTB phenol resole to clarify the reaction mechanism. Reaction products were characterized with 1H‐NMR and IR techniques. Spectral examination of the model reaction showed that polymerization reaction proceeded via ene reaction of the quinone methide formed at the end group of the resole with the allylic positions of the fatty ester. Rubbery polymers were obtained with linseed oil using 10 to 40% of the different resoles. Hard, load bearing and tough materials were obtained at 40% phenolic resin loading. Mechanical properties of the materials were characterized by dynamic mechanical analyzer (DMA) and stress–strain tests. The best mechanical and thermal properties were obtained with PEP resole which showed a storage modulus of 350 MPa and a tan δ peak at 65°C. Storage moduli of 275, 250, and 30 were obtained for PPP, PTB, and PTO resoles‐linseed oil polymers, respectively. At the same phenolic resin loading, elongation at break and swelling ratios in CH2Cl2 increased with the longer alkyl substitution on the resole resins. The highest thermal stability was observed by PEP resole–linseed oil polymer which has a 5% weight loss temperature of 340°C as determined by TGA. The lowest thermal stability was observed for PTB resole‐linseed oil polymer at 220°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Experimental and statistical study of the effects of material properties, curing agents, and process variables on the production of thermoplastic vulcanizates
Authors: Trifkovic M. , Sheikhzadeh M. , Choo K. , Rohani S.
Published: May 2010

A comprehensive experimental study together with statistical analysis was performed to identify the optimal process conditions, materials selection, and curing system for the production of thermoplastic vulcanizates (TPVs) based on EPDM rubber and polypropylene. Two types of curing systems were studied together with five different types of EPDM rubber. The TPV products were assessed according to elastic modulus and degree of swelling (indicators of crosslink density), ultimate tensile strength, ultimate elongation, tear strength, and compression set. A design of experiments method was applied to minimize the number of experiments and to obtain response surface and regression models for this complex and highly interactive system. From the modeling results, optimum values for the influential factors were obtained to achieve the target end product properties. It was found that a phenolic resin‐based curing system gave the best product properties and that the most influential factors were the rubber characteristics (ethylene content, ethylidene norbornene content, and molecular weight) and the polypropylene content in the formulation. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Control of thermo reversible gelation of methylcellulose using polyethylene glycol and sodium chloride for sustained delivery of ophthalmic drug
Authors: Bain Mrinal Kanti , Bhowmik Manas , Maity Dipanwita , Bera Nirmal Kumar , Ghosh Santinath , Chattopadhyay Dipankar
Published: May 2010

The effect of molecular weight of polyethyleneglycol (PEG) and sodium chloride (NaCl) on the gelation temperature of methylcellulose (MC) was studied with the objective to develop a MC based formulation for sustained delivery of ophthalmic drug. The gelation temperature of 1% MC was 60 ± 0.40°C. It was found that the gelation temperature of MC was reduced with the addition of 10% PEG and extent of reduction of gelation temperature was depended on the molecular weight of PEG at same PEG concentration of 10%. The gelation temperature of MC was reduced by 10.4 to 5.9°C with the increasing molecular weight of PEG starting from 400 to 20,000 (Mn) depending on the method of determination of gelation temperature. To reduce the gelation temperature of MC close to physiological temperature (37°C), 6% NaCl was added in the different MC‐PEG combinations containing different molecular weight of PEG. It was observed that the drug release time increased from 5 to 8 h with the increase in molecular weight of PEG from 400 to 20,000 (Mn) and this was due to the maximum viscosity and gel strength of MC‐PEG20000‐NaCl ternary combination. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Mechanical and dynamic mechanical analysis of hybrid composites molded by resin transfer molding
Authors: Ornaghi Heitor Luiz , Bolner Alexandre Sonaglio , Fiorio Rudinei , Zattera Ademir Jose , Amico Sandro Campos
Published: May 2010

This work aims to evaluate the performance of glass/sisal hybrid composites focusing on mechanical (flexural and impact) and dynamic mechanical analyses (DMTA). Hybrid composites with different fiber loadings and different volume ratios between glass and sisal were studied. The effect of the fiber length has also been investigated. The densities of the composites were compared with the theoretical values, showing agreement with the rule of mixtures. The results obtained in the flexural and impact analysis revealed that, in general, the properties were always higher for higher overall reinforcement content. By DMTA, an increase in the storage and loss modulus was found, as well as a shift to higher values for higher glass loading and overall fiber volume. It was also noticed an increase in the efficiency of the filler and the calculated activation energy for the relaxation process in the glass transition region. The fiber length did not significantly change the results observed in all analyses carried out in this work. The calculated adhesion factor increased for higher glass loadings, meaning the equation may not be applied for the system studied and there are other factors, besides adhesion influencing energy dissipation of the composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Effect of different salts on PVAc/PVdF‐co‐HFP based polymer blend electrolytes
Authors: Ulaganathan M. , Rajendran S.
Published: May 2010

Solid polymer electrolytes comprising poly(vinyl acetate) (PVAc), and poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVdF‐co‐HFP), low molecular weight plasticizer [Ethylene Carbonate (EC)] and different lithium salts (LiBF4, LiClO4, and LiCF3SO3) are prepared by solution casting technique. The electrolyte films are subjected to various characterization techniques such as XRD, FTIR, DSC, SEM and ac impedance analysis. Ionic conductivity is obtained as a function of frequency at various temperatures ranging from 302 to 363 K. The maximum room temperature ionic conductivity is found to be 1.18 × 10−3 S cm−1 for the film containing LiBF4 and the temperature dependent ionic conductivity values seem to obey VTF relation. Microstructure of the samples has been depicted by means of scanning electron microscope. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Structure and properties of biaxial‐oriented crystalline polymers by solid‐state crossrolling
Authors: Yang Y. , Keum J. , Zhou Z. , Thompson G. , Hiltner A. , Baer E.
Published: May 2010

The effect of biaxial orientation by solid‐state crossrolling on the morphology of crystalline polymers including polypropylene (PP), high density polyethylene (HDPE) and Nylon 6/6 was investigated with polarized optical microscopy, atomic force microscopy, wide‐angle X‐ray scattering, and small‐angle X‐ray scattering techniques. It was found that crossrolling gradually changed the initial spherulitic structure into a biaxially oriented crystal texture with chain axis of crystals becoming parallel to the rolling direction for all three polymers. The effect of microstructure change on the macromechanical properties was studied in tension at both ambient temperature and −40°C. In tension at room temperature, the localized necking deformation of HDPE and PP control changed upon orientation into homogeneous deformation for the entire sample length. This was attributed to that the oriented crystal morphology eliminated the stress concentration, which existed in the original spherulitic structure from lamellae orientation in the polar and equatorial regions. At ambient conditions, the elastic moduli of HDPE and PP were found to decrease slightly with orientation whereas the modulus of Nylon 6/6 increased with increasing orientation. This was due to the fact that the amorphous chains of HDPE and PP are in a rubbery state and orientation increased the shear relaxation in the orientation direction but the amorphous chains of Nylon 6/6 are in the glassy state inhibited the shear relaxation. Both the yield stress and strain hardening exponent increased with increasing orientation for all three polymers. In tension at −40°C, orientation changed the failure mechanism of all three polymers from brittle fracture into ductile failure, as the original spherulitic structure was changed into an oriented structure with chain axis of crystals becoming parallel to the tension direction, which allowed chain slip deformation of crystals and resulted in oriented samples showing ductile failure. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
The effects of isocyanate index on the properties of aliphatic waterborne polyurethaneureas
Authors: Wang Ke , Peng Ya , Tong Rongbai , Wang Yan , Wu Zengyong
Published: May 2010

The aliphatic waterborne polyurethaneureas (WPU) with different isocyanate index (R) were synthesized by isophorone diisocyanate (IPDI) and polyester glycol via prepolymer mixing method. The effects of the R value on the structure and the properties of the resultant polymers have been analyzed. The polymer with a certain R value (R = 1.44) exhibited excellent mechanical properties with both high tensile strength (55 MPa) and high elongation at break (1400%). The water resistance and the thermal stabilities of WPUs have been improved with the increase of R. The results were interpreted in terms of the structures associated with the micro‐phase separation. According to differential scanning calorimeter (DSC) analysis, the microphase separation degree was elevated by increasing R value. FTIR spectrum showed the more R value, the more hydrogen bonded urea groups. No crystallinity was found in X‐ray diffraction (XRD) patterns showing the typical amorphous morphologies of IPDI‐based WPUs. Thus the primary driving force for microphase separation was the hydrogen bonding between urethane and urea groups, making significant influence on the properties of WPUs, as shown in dynamic mechanical analyzes. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Molecular activation energies (Δμ*2) of L‐lysine, L‐tyrosine, L‐proline, DL‐alanine, glycerol, orcinol, iodine, DTAB, and TMSOI for blending with melamine‐formaldehyde‐polyvinylpyrrolidone polymer resin illustrated with SEM
Authors: Singh Man , Kumar Vinod , Kale R. K. , Jain C. L.
Published: May 2010

Efficient molecular mixing together is a key precondition for industrial exploitation of individual macromolecules for potential product development and quality assurance with resource saving mechanism. Conceptually, MFP (melamine‐formaldehyde‐polyvinylpyrrolidone) polymer resin was mixed with amino acids (L‐lysine, L‐tyrosine, L‐proline, DL‐alanine), nonionic surfactants (glycerol, orcinol), iodine as metal and cationic surfactants (DTAB, TMSOI) as dispersants, in 4 : 1 ratio, w/w. A mutual molecular dispersion occurs at a cost of molecular activities with utilization of a sufficient amount of activation energies. The activation energies (Δμ*2, kJ mol−1) were derived from intrinsic viscosities ([η], kg/L) and partial molar volumes (V2, 10−6 m3/mol), which were calculated from experimental data of viscosities (η, N s m−2) and apparent molar volumes (V2, 10−6 m3/mol) of 0.005, 0.007, 0.009, and 0.0011 g/mL aqueous samples of the dispersants at 304.15 K. The limiting data were fitted to standard activation energy equations and were analyzed to assess potential of their micromixing. Densities (ρ/103 kg m−3) for apparent molar volume (V2/10−6 m3 mol−1) and viscosity (η, 0.1N, s m−2 = 0.1 kg m−1 s−1, = 1 poise, SI unit) were also measured with weight method. The Δμ*2< 0, in arrange of −48.35 to −118.03 kJ/mol were noted that inferred effective micromixing evidenced with SEM images of the blends. The Δμ*2, kJ mol−1 data are as glycerol (−118.03) > TMSOI (−117.55) > DTAB (−102.93) > orcinol (−101.54) > MFP‐R (−93.71) > iodine (−59.32) > L‐proline (−59.27) > L‐lysine (−55.87) > DL‐alanine (−55.04) > L‐tyrosine (−53.04) > water (−48.35) orders with maximum utilization of Δμ*2, glycerol. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010