bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and characterization of hybrid nanocomposites comprising poly(vinyl alcohol) and colloidal silica
Authors: Sarkar Mousumi De , Deb Paromita 
Published: April 2009

AbstractOrganic–inorganic hybrid composite films were developed using poly(vinyl alcohol) (PVA) and an aqueous dispersion of colloidal silica of initial particle size of 15–30 nm. The hybrid films, prepared with varied proportion of colloidal silica (10–90 phr), were found to be transparent, indicating the nanolevel dispersion of the inorganic component over the polymer. Morphological studies further revealed no significant agglomeration of the silica domains embedded into the polymer matrix. A depression in glass transition temperature of PVA is observed with increasing proportion of silica. The degree of crystallinity also showed a decreasing trend with increasing amount of silica. However, the composite films demonstrated superior mechanical performances, higher resistances to dissolution in boiling water, and lower permeability compared with virgin PVA, owing to the better interaction between PVA and silica as well as the reinforcing action of nanosilica particles in the polymer matrix. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 27:152–162, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20129
Physically and chemically modified polycarbonate by metal ion implantation
Authors: Nathawat Rashi , Vijay Y. K. , Kumar P. , Kulriya P. , Ganesan V. , Sathe V. 
Published: April 2009

AbstractChanges in physical and chemical properties have been studied for polycarbonate (PC) implanted by 100 keV Ni+ with various fluences from 1 × 1014 to 1 × 1016 ions/cm2. Changes in the surface morphology and composition have been observed with atomic force microscopy and X‐ray diffraction (XRD). Ni particles as precipitates in PC were observed by cross‐section transmission electron microscopy at the 100‐nm depth. Ion implantation induces changes in the topography of PC as indicated by a dramatic increase in surface roughness with ion fluence. Implanted metal ions show direct evidence of compound formation on the surface. Chemical changes in the surface region have been observed by Raman spectroscopy and UV–vis spectroscopy. UV–vis absorption analysis indicates a drastic decline in optical band gap from 5.46 to 1.76 eV at an implanted dose of 1 × 1016 ions/cm2. It is shown that partial destruction of the original chemical bonding under ion implantation leads to the creation of new amorphous and graphite‐like structures, which are confirmed by Raman spectroscopy. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 27:143–151, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20130
Efficient utilization of plastic waste through product design and process adaptation: A case study on stiffness enhancement of beams produced from plastic lumber
Authors: Pio Cristian , Greco Antonio , Maffezzoli Alfonso , Marseglia Alessandro 
Published: April 2009

AbstractThe aim of the present work is the development of a method for structural reinforcement of beams obtained by in‐mold extrusion of plastics from solid urban waste. The beams obtained by in‐mold extrusion are commonly used for outdoor furniture and structures. The material used for such applications is mainly composed of low‐density polyethylene derived from bags and films, with small amounts of high density polyethylene and polypropylene, as well as traces of polyethylene terephthalate. This material is usually referred to as “plastic lumber.” Plastic lumber products have a low stiffness, which results in high deflections under flexural loads, particularly under creep loading. In this study, reinforcing rods of high aspect ratio were incorporated into plastic lumber beams in specific positions with respect to the cross section of the beam. The reinforcement of the plastic lumber beams with fine rods is introduced in the typical intrusion process used for the production of unreinforced beams. Glass fiber reinforced pultruded rods were chosen for this purpose from a preliminary evaluation of different materials. Different diameter glass fiber reinforced pultruded rods, including surface‐abraded systems to increase the roughness, were used for the reinforcement of plastic lumber beams. The reinforced beams were tested in terms of flexural stiffness, creep resistance, and pullout resistance of the embedded rods. The results obtained from the mechanical tests showed a significant enhancement of flexural stiffness and creep resistance behavior. The performance at higher stress levels was shown to be significantly dependent on the interfacial adhesion between rods and polymer matrix. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 27:133–142, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20131
Variable mold temperature to improve surface quality of microcellular injection molded parts using induction heating technology
Authors: Chen Shia‐Chung , Lin Yu‐Wan , Chien Rean‐Der , Li Hai‐Mei 
Published: April 2009

AbstractMicrocellular foam injection molding provides many advantages over conventional foams and their unfoamed counterparts, but its applications are limited by visible surface quality problems such as silver streaks and swirl marks. In this study, we propose a variable mold temperature method to improve the surface quality of molded parts. Electromagnetic induction heating is used in combination with water cooling to achieve rapid mold surface temperature control during the microcellular foam injection molding process. The effect of processing parameters, such as mold temperature, melt temperature, and injection velocity on the part surface quality, was investigated using surface roughness measurements and visual inspection of the molded parts. The results show that using induction heating to increase the mold surface temperature from 100°C to 160°C can decrease surface roughness of polycarbonate moldings from 25 µm to 6.5 µm. It was also found that the flow marks formed by gas bubbles on the part surface can be removed completely at a mold temperature of 160°C. Further increases in the mold temperature show slight improvements in the surface roughness up to 180°C, at which point the surface roughness starts to level off at 5 µm. This surface roughness value reflects an 80% improvement without a significant increase in cycle time over parts molded at a mold temperature of 60°C using water heating. Higher melt temperature and faster injection speed will also improve the surface quality of microcellular injection molded parts but not as significantly. The usefulness of a variable mold temperature in improving part surface quality during microcellular foam injection molding has been successfully demonstrated. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 27:224–232, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20133
Overview of polymer micro/nanomanufacturing for biomedical applications
Authors: Yi Allen Y. , Lu Wu , Farson Dave F. , Lee L. James 
Published: April 2009

AbstractMicro/nanotechnology is initiated from the electronics industry. In recent years, it has been extended to micro/nanoelectromechanic system for producing miniature devices based on silicon and semiconductor materials. However, the use of these hard materials alone is inappropriate for many biomedical devices. Soft polymeric materials possess many attractive properties such as high toughness and recyclability. Some possess excellent biocompatibility, are biodegradable, and can provide various biofunctionalities. Proper combinations of micro/nanoelectronics, polymers, and biomolecules can lead to new and affordable medical devices. In this paper, we briefly review several cleanroom and noncleanroom techniques related to micro/nanomanufacturing of polymeric materials. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 27:188–198, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20134
Injection molding control: From single cycle to batch control
Authors: Yang Yi , Yao Ke , Gao Furong 
Published: April 2009

AbstractClosed‐loop control of key process variables in injection molding has become an essential part of the quality assurance system. Advanced control algorithms such as adaptive control and model predictive control have been adopted to deal with the inherent process nonlinearity and time‐varying characteristics. These control algorithms are all focused on single‐cycle control performance. Recently, a multicycle, two‐dimensional model predictive learning control has been developed for batch process control. This method has been applied to injection molding. In this paper, the basic principles of these control algorithms are introduced, with the control performance demonstrated by injection velocity control. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 27:217–223, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20135
Rapid thermal cycling of injection molds: An overview on technical approaches and applications
Authors: Yao Donggang , Chen Shia‐Chung , Kim Byung H. 
Published: April 2009

AbstractA heated mold with temperature above the polymer‐softening temperature is highly desired in precision injection molding. The elevated mold temperature reduces unwanted freezing during the injection stage, thus improving moldability and enhancing part quality. The resulting advantages include, but are not limited to, longer flow path, improved feature replication and surface transcription, reduced molecular orientations and residual stresses, smoother surfaces of composites, better control of crystallization, stronger weld lines, etc. However, the heated mold needs to be rapidly cooled during the cooling stage to maintain a short cycle time. Despite the large body of available literature, mold rapid heating and cooling does not represent a well‐developed area of practice. Development of capable techniques for rapidly heating and cooling a mold with a relatively large mass is technically challenging because of the constraints set by the heat transfer process and the endurance limits set by the material properties. This article attempts to offer a constructive overview on the state of the art in mold rapid heating and cooling, with the goal of explaining the working mechanisms and providing unbiased accounts of the pros and cons of existing processes and techniques. Successful applications of existing processes are highlighted and potential improvements of these processes are suggested. The article further intends to provide a fundamental understanding of the constituent elements and corresponding building blocks needed in a workable mold with a rapid heating and cooling capability. An increased understanding of these elements will facilitate the development of more capable new processes. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 27:233–255, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20136
Study of oriented polyvinyl chloride pipes by inner‐pressing expansion
Authors: Dong W. Y. , Ren D. Y. , Wu D. M. , You S. B. , Zhang B. 
Published: April 2009

AbstractBased on a new expansion technology for oriented polyvinyl chloride (PVC‐O) pipes, the stress distribution in pipe wall during expansion and the efficiency of the heating process are analyzed theoretically. According to the results of theoretical calculation, the optimal parameter and strength variation for different expansion ratios are studied experimentally. Theoretical calculation results show that the hoop stress and radial stress in pipe wall are near‐linearly distributed, and they are approximately equal. The heating efficiency is gotten by heat transfer calculations for different oil bath temperatures and heating times. After expansion, the intensity and Young's modulus are increased but elongation at break is reduced. All the variations in properties enlarge along with the raise of expansion ratio. Fine appearance and high‐strength PVC‐O pipe can be achieved by optimizing the expansion parameter. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 27:172–181, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20137
Process optimization and effects of material properties on numerical prediction of warpage for injection molding
Authors: Gao Yuehua , Turng Lih‐Sheng , Wang Xicheng 
Published: April 2009

AbstractThis study aims to illustrate the importance of accurate material property data in the numerical simulation of injection molding by elucidating the effects of variation in material properties on warpage prediction. In addition, it presents an adaptive optimization method based on the Kriging surrogate model that has been developed to intelligently determine the optimal processing parameters for minimizing warpage in a box‐shape part with different and stepwise wall thicknesses. The Kriging surrogate model is a statistics‐based interpolation technique that provides the approximate functional relationship between the performance variables of interest, like warpage, and the factors affecting them, such as the processing parameters. Based on optimal processing parameters, the sensitivity of warpage prediction to two of the most important material properties—shear viscosity and the pvT (pressure–specific volume–temperature) relationship—were analyzed. It is well known that the material property model constants used for numerical simulation can sometimes vary significantly due to inherent experimental measurement errors, the resolution of the testing device, and/or the way the curve fitting is performed to determine the model constants. The results showed that hypothetical and yet reasonable variations in the shear viscosity model constants and in the pvT relationship could significantly affect the magnitude of warpage prediction. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 27:199–216, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20138
Thermoregulatory sympathetic nervous system activity and diet‐induced waist‐circumference reduction in obese Japanese women
Authors: Fujibayashi Mami , Hamada Taku , Matsumoto Tamaki , Kiyohara Natsuki , Tanaka Seitaro , Kotani Kazuhiko , Egawa Kahori , Kitagawa Yoshinori , Kiso Yoshinobu , Sakane Naoki , Moritani Toshio 
Published: April 2009

AbstractThe present study is designed to investigate how and to what extent sympathovagal behavior in a balanced low‐calorie diet relates to favorable changes of body mass, waist circumference, and/or metabolic risk factors. The study involved 28 mildly obese women without clinical complications, who underwent an 8‐week calorie restriction program using a 1,200‐kcal daily diet with an adequate nutrient content; including two regular meals, and one formula meal replacement. All subjects were examined before and after the dietary intervention. We measured anthropometric parameters, blood pressure, and biochemical blood profiles for lipid metabolism. Autonomic nervous system activity was evaluated by heart rate variability power spectral analysis. The dietary intervention induced moderate, but significant reduction of waist circumference (−5.3% ± 0.8%), body fat percentage (−5.8% ± 0.8%), and body mass (−6.6% ± 0.5%). Linear regression analysis showed that Δvery low frequency (VLF) power reflecting energy metabolic‐ and thermoregulatory sympathetic function significantly correlated to Δwaist circumference (r = −0.53, P < 0.01), Δbody fat percentage (r = −0.39, P < 0.05), Δbody mass (r = −0.43, P < 0.05), ΔHDL‐cholesterol/total cholesterol ratio (HDL‐C/TC) (r = 0.62, P < 0.001), and Δnonesterified fatty acids (NEFA) (r = 0.56, P < 0.01). A stepwise multiple regression analysis additionally revealed that Δwaist circumference (P = 0.024), ΔHDL‐C/TC (P = 0.013), and ΔNEFA (P = 0.016) were significant and independent factors, which contributing to the variance in ΔVLF power (r2 = 0.61). Although causes and consequences of obesity continue to elude researchers, the present study indicates that thermoregulatory sympathetic activity relates to moderate waist‐circumference reduction together with favorable changes of blood lipid profiles after short‐term dietary modification in mildly obese women. Am. J. Hum. Biol. 2009. © 2009 Wiley‐Liss, Inc.
Breastfeeding structure as a test of parental investment theory in Papua New Guinea
Authors: Tracer David P. 
Published: April 2009

AbstractEvolutionary parental investment theory predicts that parents invest preferentially in offspring best able to translate investments into fitness payoffs. It has also been proposed that where the reproductive prospects of offspring are directly correlated with parental investment and variance in fertility is higher for males than females, parents in better condition should bias investment toward males while those in poorer condition should bias investment toward females. Lactation is arguably among the costliest forms of investment expended by mothers and is thus expected to be allocated in ways consistent with fitness payoffs. Quantitative data collected among 110 Papua New Guinean mother‐infant pairs during 470 h of focal follows on nursing frequency and duration and responses to infant demands by maternal and offspring characteristics are presented to provide empirically‐based descriptions of infant care and tests of evolutionary parental investment theory. Results indicate that mothers show very high levels of investment in offspring. However, although breastfeeding in developing countries is often characterized as on‐demand, fussing and crying by infants were only attended to with breastfeeding about 30% of the time. Contrary to expectations of parental investment theory that parents should invest less in poorer quality offspring, mothers increased investment in offspring in poorer condition. The expectation that mothers in better condition would bias investment toward male offspring was also not supported; better nourished mothers biased investment toward female offspring. This study illustrates how infant feeding data may be used for testing larger evolutionary questions such as those derived from parental investment theory. Am. J. Hum. Biol. 2009. © 2009 Wiley‐Liss, Inc.
Integration of proximate and evolutionary explanation of reproductive strategy: The case of callitrichid primates and implications for human biology
Authors: Tardif Suzette D. , Ross Corinna N. 
Published: April 2009

AbstractWe offer examples of how proximate and evolutionary forms of argument may inform each other in better understanding reproductive strategy in callitrichid primates, the smallest of the anthropoid primates. In addition, we illustrate how comparative approaches, when applied judiciously, can aid in the formulation of hypotheses regarding even seemingly unique traits within a taxonomic group. In the first example, examination of the nature of genetics in cytokine systems that leads to altered ovulation number in sheep suggests some relatively simple changes could explain both the adaptation of increased ovulation number in marmosets and the subsequent decrease in ovulation number in the closely related species, callimico. In the second example, the role of body size and phylogeny in explaining the role of maternal energy constraints upon gestation and lactation is explored, leading to additional hypotheses regarding these relations in a species that is both small but also in a phylogenetic line selected for slow reproduction. Finally, the role of comparative data in the study of proximate and evolutionary explanations of “unique” human reproductive strategies is discussed. Am. J. Hum. Biol., 2009. © 2009 Wiley‐Liss, Inc.
Not really identical: Epigenetic differences in monozygotic twins and implications for twin studies in psychiatry
Authors: Haque F. Nipa , Gottesman Irving I. , Wong Albert H.C. 
Published: April 2009

AbstractClassical twin studies in the field of psychiatry generally fall into one of two categories: (1) those designed to identify environmental risk factors causing discordance in monozygotic (MZ) twins and (2) those geared towards identifying genetic risk factors. However, neither environment nor differences in DNA sequence can fully account for phenotypic discordance among MZ twins. The field of epigenetics – DNA modifications that can affect gene expression – offers new models to understand discordance in MZ twins. In the past, MZ twins were regarded as genetically‐identical controls for differing environmental conditions. In contrast, the evolving current concept is that epigenetic differences between MZ twins may modulate differences in diverse phenotype, from disease to personality. In this article, we review some twin studies, and discuss the dynamic interactions between stochastic, environmental, and epigenetic variables that influence neurobiological phenotypes. © 2009 Wiley‐Liss, Inc.
Twinning on the brain: The effect on neurodevelopmental outcomes
Authors: Luu Thuy Mai , Vohr Betty 
Published: April 2009

AbstractTwinning is currently considered a complex multifactorial trait. Few studies have explored how the unique genetic and environmental influences that create twinning affect phenotypes and outcomes. Previous data has shown that twins account for a significant proportion of preterm and low‐birth‐weight infants, who are at risk for long‐term neurodevelopmental disabilities such as cerebral palsy and cognitive impairment. More recently, it has been postulated that even without these co‐morbidities, twinning in and of itself may incur a neurodevelopmental disadvantage even among term newborns. The purpose of this review is to report primarily on neuromotor outcomes of twins compared to singletons. In addition, we describe specific environmental risk factors among twins which are associated with poorer outcomes. Several putative neurodevelopmental modulators are explored, including death of a co‐twin, chorionicity, birth weight discordance, and twin‐twin transfusion. By teasing out environmental influences that potentially influence neurocognitive outcomes, families can receive more specific counseling and developmental services can be provided to those twins at especially high risk. © 2009 Wiley‐Liss, Inc.
MFM/geneticist view on prenatal management of twins
Authors: O'Brien Barbara M. 
Published: April 2009

AbstractTwin pregnancies are associated with an increase in both fetal and maternal morbidity and mortality. Health care supervision is complex, increasingly requiring care from maternal‐fetal medicine specialists. This review discusses optimal twin prenatal management, which includes recognizing increased twin pregnancy risks specific to twin‐types; counseling families regarding fetal complications, ranging from prematurity to cerebral palsy; screening for aneuploidy and open neural tube defects; specific twin guidelines for diagnostic testing, including chorionic villus sampling and amniocentesis; and monitoring for maternal complications. © 2009 Wiley‐Liss, Inc.
Clinical significance of chimerism
Authors: Abuelo Dianne 
Published: April 2009

AbstractTwins have been previously classified as either monozygotic or dizygotic. In recent years, fascinating, non‐traditional mechanisms of twinning have been uncovered. We define chimerism versus mosaicism, touch on chimerism in the animal world, and explain timing of chimerism in humans. In addition, we discuss when to suspect chimerism in patients, and how to proceed with diagnostic evaluation and confirmation. © 2009 Wiley‐Liss, Inc.