bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimization of stress wave propagation in a multilayered elastic/viscoelastic hybrid composite based on carbon fibers/carbon nanotubes
Authors: Safdari Masoud , Al‐Haik Marwan S. 
Published: December 2011

AbstractThe hypothesis of incorporating carbon nanotubes (CNTs) into the interfacial layers of fiber‐reinforced polymer composites fiber‐reinforced Polymers (FRPs) to enhance their mechanical properties and mitigate the stress wave propagation during a blast event is investigated. A numerical model is developed to simulate the stress wave propagation in a laminated elastic/viscoelastic FRP. Coupled with multiobjective optimization paradigms, the optimal CNTs contents in the interfacial layers are determined to minimize the stress‐to‐strength ratio in each layer. A case study demonstrating the design of a five‐layered FRP subjected to a blast event is presented. The simulation revealed that the viscoelastic properties of the matrix material contribute significantly to the energy dissipation during stress wave propagation. It is shown that addition of 0.69% CNTs by volume to the epoxy interface significantly enhances the ability of composite to resist blast loading. Results were compared with a standard model that assumes only elastic behavior. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers
Properties of PMMA/Carbon nanotubes nanocomposites prepared by “grafting through” method
Authors: Salami‐Kalajahi Mehdi , Haddadi‐Asl Vahid , Behboodi‐Sadabad Farid , Rahimi‐Razin Saeid , Roghani‐Mamaqani Hossein 
Published: December 2011

AbstractA number of batch polymerizations were performed to study the effect of multi‐walled carbon nanotubes (MWCNTs) on the properties of PMMA/MWCNTs nanocomposites. To improve the dispersion of nanotubes in PMMA matrix, MWCNTs were functionalized with methacrylate groups via a four‐step modification process and the modified nanoparticles were used to synthesize the nanocomposites. The prepared samples were characterized by Raman spectroscopy, thermogravimetric analysis, dynamic mechanical thermal analysis, differential scanning calorimetry, gel permeation chromatography, UV–visible, and TEM techniques. According to the results, modified nanotubes improved thermal and mechanical properties better than the pristine MWCNTs. The main improvement in the mechanical and thermophysical properties was achieved for the nanocomposite containing 0.5 wt% of MWCNTs. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers
Preparation and properties of thermoplastic starch/montmorillonite nanocomposites using N,N‐bis(2‐hydroxyethyl)formamide as a new additive
Authors: Dai Hongguang , Sheng Xianliang , An Liping , Liu Naren , Yu Jiugao , Ma Xiaofei 
Published: December 2011

AbstractN,N‐Bis(2‐hydroxyethyl)formamide (BHF) was synthesized efficiently and used as a new additive to prepare thermoplastic starch/montmorillonite (TPS/MMT) nanocomposites. Here, BHF acted as both plasticizer for TPS and swelling agent for MMT. The hydrogen bond interaction among BHF, starch, and MMT was proven by Fourier transform infrared (FTIR) spectroscopy. By scanning electron microscope (SEM), starch granules were completely disrupted. Atomic force microscopy demonstrated that partially exfoliated TPS/MMT nanocomposites were formed. The crystallinity of corn starch, MMT, BHF‐plasticized TPS (BTPS), and TPS/MMT nanocomposites was characterized by X‐ray diffraction (XRD), XRD demonstrated that partially intercalated TPS/MMT nanocomposites were formed. The water resistance of TPS/MMT nanocomposites increased compared with that of pure BTPS. Mechanical properties of BTPS and TPS/MMT nanocomposites were examined. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers
The glass‐forming ability and thermal stability of novolac–phenolic resin
Authors: Guo Kai , Bian Xiufang , Qin Jingyu , Yang Lei 
Published: December 2011

AbstractGlass‐forming ability and thermal stability of novolac–phenolic resin with different contents of curing agent hexamethylenetramine (HMTA) are investigated. Melt fragility (Mg) and Tgd (Tgd = Tg/Td) are proposed to characterize glass‐forming ability and thermal stability of the novolac–phenolic resin, respectively. It is found that Mg has a negative linear relationship with Tgd. The lower Mg represents the better glass‐forming ability of liquid phenolic resin while the higher Tgd represents the better thermal stability of the fully cured phenolic resin. Further more, Mg establishes a kinetic relationship between glass‐forming ability of liquid uncured and thermal stability of fully cured novolac–phenolic resin in terms of comparing with Tgd. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers
Effects of multiple carbon fillers on the rheology of polycarbonate‐based composites
Authors: Via Michael D. , Morrison Faith A. , King Julia A. , Beach Edsel A. , Wiese Kyle R. , Bogucki Gregg R. 
Published: December 2011

AbstractAdding conductive carbon fillers to insulating thermoplastic polymers increases the electrical conductivity of the resulting composite, which could allow them to be used in electrostatic dissipative and semiconductive applications. Adding fillers often increases viscosity, which can make the material more difficult to process. In this study, three different carbon fillers [carbon black (CB), carbon nanotubes (CNT), and exfoliated graphite nanoplatelets (GNP)] were studied via three different combinations of two different fillers (CB/CNT, CB/GNP, and CNT/GNP). These filler combinations were studied via three 32factorial designs, which considered the following loading levels: CB: 0, 2, and 5 wt%; CNT: 0, 1, and 5 wt%; and GNP: 0, 2, and 5 wt%. These composites were compounded, injection molded, and tested for electrical conductivity and steady shear viscosity. CB and GNP exhibited classic filler behavior, increasing the composite viscosity with increased filler loading. CNT acted differently, lowering the composite viscosity with increased filler loading. When CB and GNP were combined, the viscosity increase was additive. When CNT was combined with either CB or GNP, the resultant composite had a lower viscosity than the corresponding single filler composite with equivalent loadings of CB or GNP. This viscosity lowering effect of CNT, even at loadings as low as 1 wt%, allows for increased filler loadings of CB or GNP with little impact on processability. Five different formulations (four containing two filler combinations) could be used for electrostatic dissipative applications and seven different formulations (six containing two filler combinations) may be used for semiconductive applications. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers
Towards an Efficient Protocol for the Determination of Triterpenic Acids in Olive Fruit: A Comparative Study of Drying and Extraction Methods
Authors: Goulas Vlasios , Manganaris George A. 
Published: December 2011

ABSTRACTIntroductionTriterpenic acids, such as maslinic acid and oleanolic acid, are commonly found in olive fruits and have been associated with many health benefits. The drying and extraction methods, as well as the solvents used, are critical factors in the determination of their concentration in plant tissues. Thus, there is an emerging need for standardisation of an efficient extraction protocol that determines triterpenic acid content in olive fruits.ObjectiveTo evaluate common extraction methods of triterpenic acids from olive fruits and to determine the effect of the drying method on their content in order to propose an optimum protocol for their quantification.MethodologyThe efficacy of different drying and extraction methods was evaluated through the quantification of maslinic acid and oleanolic acid contents using the reversed‐phase HPLC technique.ResultsData showed that ultrasonic assisted extraction with ethanol or a mixture of ethanol:methanol (1:1, v/v) resulted in the recovery of significantly higher amounts of triterpenic acids than other methods used. The drying method also affected the estimated triterpenic acid content; frozen or lyophilised olive fruit material gave higher yields of triterpenic acids compared with air‐dried material at both 35°C and 105°C.ConclusionThis study provides a rapid and low‐cost extraction method, i.e. ultrasonic assisted extraction with an eco‐friendly solvent such as ethanol, from frozen or lyophilised olive fruit for the accurate determination of the triterpenic acid content in olive fruit. Copyright © 2011 John Wiley & Sons, Ltd.
Crystallization behavior and nucleation analysis of poly(l‐lactic acid) with a multiamide nucleating agent
Authors: Song Ping , Wei Zhiyong , Liang Jicai , Chen Guangyi , Zhang Wanxi 
Published: December 2011

AbstractTo accelerate the crystallization of poly(L‐lactic acid) (PLLA) and enhance its crystallization ability, a multiamide nucleator (TMC) was introduced into the PLLA matrix. The thermal characteristics, isothermal and nonisothermal crystallization behavior of pure PLLA and TMC‐nucleated PLLA were investigated by differential scanning calorimetry. The determination of thermal characteristics shows that the addition of TMC can significantly decrease the onset temperature of cold crystallization and meanwhile elevate the total crystallinity of PLLA. For the isothermal crystallization process, it is found that the overall crystallization rate is much faster in TMC‐nucleated PLLA than in pure PLLA and increases as the TMC content is increased, however, the crystal growth form and crystalline structure are not influenced much despite the presence of TMC. In the case of nonisothermal crystallization, the nucleation efficiency and nucleation activity were estimated and the results indicate that excellent nucleation‐promoting effect could be achieved when the weight percentage of TMC is chosen between 0.25% and 0.5%. Polarized optical microscopy observation reveals that the nuclei number of PLLA increases and the spherulite size reduces greatly with the addition of TMC. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers
Residual stresses and thermoviscoelastic deformation of laminated film prepared for film insert molding
Authors: Kim Sung Ho , Kim Seong Yun , Lee Seung Hwan , Youn Jae Ryoun 
Published: December 2011

AbstractResidual stresses and thermoviscoelastic deformation of a laminated film utilized for film insert molding was investigated through measurement of thermal expansion coefficient (CTE) and relaxation modulus. Thermoviscoelastic deformation of the film was also analyzed with numerical analysis by applying measured relaxation modulus, CTE, and residual stress to finite element method (FEM). Stress relaxation of the pristine film showed significantly different behavior from that of the unannealed film during annealing. Effects of the CTE and relaxation modulus on the thermoviscoelastic deformation were predicted by considering thermal shrinkage and structural relaxation. Moreover, numerical results on thermoviscoelastic deformation were in good agreement with experiments when initial stress distribution in the solid specimen was applied to the numerical analysis. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers
Siloxane polymers containing azo moieties synthesized by click chemistry for photo responsive and liquid crystalline applications
Authors: Pandey Someshwarnath , Kolli Balakrishna , Mishra Sarada P. , Samui Asit B. 
Published: December 2011

AbstractThree new types of siloxane‐based photoactive liquid crystalline polymers containing azo side groups were synthesized through the click chemistry route. The polymers having molecular weight range of 14,000–34,000 g mol−1 were soluble in most of the polar solvents like chloroform, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, and dichloromethane. The photoresponsive trans–cis photoisomerization under UV radiation and cis–trans relaxation process in dark for the polymers were studied. The isomerization rate constants were found to be 0.01–0.04 sec−1 and 1.16*10−4–4.67*10−4 sec−1, respectively. It has been noted that the polymers showed high intensity absorption for n‐π* in chloroform. Both trans and cis forms of azide monomers having azo moiety exhibited molar extinction coefficient (ϵmax) in the range of 22,000–33,000 L mol−1 cm−1. The thermotropic behavior of the polymers was studied by polarizing optical microscope (POM) and differential scanning calorimetry (DSC) experiments. Polymer P1 showed liquid crystalline textures of nematic droplets, whereas P2 showed smectic focal conic texture and nematic droplets. Polymer P1 was also studied for photomechanical bending on exposure to UV radiation. The polymers showed initial degradation temperature in the range of 210–275°C. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Temperature‐based fluorescence measurements of pyrene in block copolymer micelles: Probing micelle core glass transition breadths
Authors: Mok Michelle M. , Lodge Timothy P. 
Published: December 2011

AbstractGlass transition temperature (Tg) breadths are reported for polystyrene (PS) micelle cores in two series of micelle‐forming block copolymers [PS‐poly(ethylene oxide) and PS‐poly(methyl methacrylate)] with an ionic liquid solvent (1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)amide). An increased level of fluorescent molecules was induced within the cores upon rapid cooling followed by aging. Using fluorescence to monitor dye release with relaxation of this state upon heating, transition onset and end‐point temperatures were defined. The system with the lowest PS‐block molecular weight showed no evidence of a transition above 25 °C; however, in every other case, transitions were observed beginning at ∼40‐45 °C and ending at ∼60‐85 °C. These temperatures closely match PS‐block Tg results measured by differential scanning calorimetry in semidilute solutions of the same materials, suggesting that the transition temperature range correlates strongly to the transition of the cores from fully glassy to fully rubbery. Differences in transition end‐points were related to PS‐block molecular weights and relative copolymer fractions of PS. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012
Nanomechanical properties in ultrathin polymer films: Measurement on rectangular versus circular bubbles
Authors: Xu Shanhong , O'Connell Paul A. , McKenna Gregory B. , Castagnet Sylvie 
Published: December 2011

AbstractPrior studies of inflation of circular membranes of ultrathin polystyrene (PS) films have evidenced a reduced glass transition temperature (Tg) and rubbery stiffening, whose origins remain unclear. Here, we describe results from inflation of rectangular, ultrathin films of the same PS material. The bubble shapes obtained from the experiment are consistent with finite element (FE) simulations. The accuracy of three approximate solutions for modulus obtained from the inflation of the thin, rectangular films was evaluated by comparison with FE analysis. The best among the three solutions was used to determine the creep compliance and rubbery stiffness of the thin films. It is found that the reduction of Tg and the rubbery stiffening for rectangular bubbles are consistent with results obtained using circular bubbles, although there is some indication that the rectangular bubbles give somewhat greater rubbery stiffening. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012
Computational study of the patterns of weaker intramolecular hydrogen bonds stabilizing acylphloroglucinols
Authors: Mammino Liliana , Kabanda Mwadham M. 
Published: December 2011

AbstractAcylphloroglucinols (ACPLs) are polyphenolic compounds derivative from phloroglucinol, characterized by the presence of at least one COR group and exhibiting a variety of biological activities, which makes them interesting for drug development possibilities. This study investigates patterns in the ways in which weaker intramolecular hydrogen bonds contribute to their conformational stabilization, considering the CH···O H‐bonds, present in all ACPLs, and the OH···π H‐bonds, present in ACPLs in which one or more substituents contain a π bond or system sufficiently close to a phenol OH for the H‐bond to be possible. The results in vacuo and in three different solvents (chloroform, acetonitrile, and water) show that, whereas CH···O plays a significant roles in all these media, the role of OH···π decreases with increasing solvent polarity. Calculations in vacuo are performed at various levels to enable performance comparisons; calculations in solution use the polarizable continuum model. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Theoretical study of the chemical reactivity and molecular quantum similarity in a series of derivatives of 2‐adamantyl‐thiazolidine‐4‐one using density functional theory and the topo‐geometrical superposition approach
Authors: Morales‐Bayuelo Alejandro , Baldiris Rosa , Torres Juan , Torres Juan E. , Vivas‐Reyes Ricardo 
Published: December 2011

AbstractA theoretical study for the determination of chemical reactivity of a series of 2‐adamantyl‐thiazolidine‐4‐one derivatives was performed. These molecules are inhibitors of inverse transcriptase activity of human immunodeficiency virus type 1 (HIV‐1) that prevents the replication of HIV‐1 in cells without causing an appreciable effect on other retroviral particles or cellular polymerases. To determine the nature of the bond, enzyme substrate was used for quantum similarity molecular calculations, using the alignment of topo‐geometrical superposition approach, solving the problem of finding the best alignment. The reactivity descriptors provide an appropriate methodology to evaluate molecular quantum similarity of these molecular structures, in the context of the density functional theory, taking into account the electronic effects quantified by the quantum similarity descriptor of Coulomb, which turned out to be the best molecular descriptor to describe the electron correlation structures; the determination of the reactive sites is of great importance for the determination of chemical reactivity, providing a bridge between the fields of chemical reactivity, and molecular quantum similarity allows us to find new characteristics and properties of reactivity on these kinds of molecules. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Fungating Thyroid Cancer: A Complex Clinical Scenario
Authors: Nabawi A. S. , Al Wagih H. F. , Hemeida M. A. , Koraitim T. Y. , Moussa M. , Ezzat Tarek 
Published: December 2011

AbstractBackgroundMost research reporting the management of advanced thyroid cancer focuses on major aerodigestive system or vessel involvement. In the present study, we investigated patients with locally advanced thyroid cancers who presented with malignant skin infiltration. The term fungating thyroid cancer (fTC) has been used to describe such a condition.MethodsThe study was based on prospective collection of clinical, laboratory, imaging, and pathological data of all patients admitted to the head and neck and endocrine surgery unit, Main University Hospital, Alexandria School of Medicine, during the period April 2005–March 2011.ResultsEleven patients were referred with fTC, eight of whom had undergone subtotal thyroidectomy for an undiagnosed well‐differentiated thyroid cancer (DTC) in another institution. The final pathological diagnosis showed (DTC, n = 3), poorly differentiated thyroid cancer (n = 5), anaplastic cancer (n = 2), and medullary thyroid cancer (n = 1). Extensive resections and reconstruction using flaps (pectoralis major, n = 6; deltopectoral, n = 1; sternocleidomastoid, n = 1) were undertaken. Complete tumor clearance (R0) was achieved in one patient and the others had microscopic (R1, n = 6) or macroscopic (R2, n = 1) residual disease. The three patients who did not undergo operation died within one month of presentation. The latest review of the eight patients who did undergo operation ranged from 3 to 6 months, but their survival remains unknown as access for follow‐up was limited.
Religious‐based portfolio selection
Authors: Lu Jin‐Ray , Chan Chih‐Ming 
Published: December 2011

AbstractWe examine religious attendance and portfolio selection decisions for an individual with religious beliefs within a continuous‐time framework. Our findings are three‐fold. First, religious contributions increase with wealth capital, the degree of religious devotion, and an increase in the wage level. Second, religious attendance positively relates to wealth capital and the performance of stock investments, but negatively correlates with wage return rates. Third, participation in religious activities can result in declining demand for risky asset investments. Theoretically, this study explains how individuals’ portfolio choices correlate with their religious activities.
Eclogites from the Belomorian Mobile Belt (Kola Peninsula): geology and petrology
Authors: Shchipansky A.A. , Khodorevskaya L.I. , Konilov A.N. , Slabunov A.I. 
Published: December 2011

Abstract
The paper focuses on the metamorphic geology of the oldest crustal eclogites discovered in the Late Archean tonalite-trondhjemite-granodiorite (TTG) complex of the Belomorian Mobile Belt on the Kola Peninsula. Eclogite bodies are, most likely, widespread. We studied one of the key objects, the Kuru-Vaara quarry, where several tens of retrogressed eclogite blocks randomly embedded in the TTG gneisses were stripped at the benches. Based on the field observations, two visually different types of eclogites have been recognized: “southern”, strongly retrogressed coarse-grained, and “northern”, well-preserved fine-grained. The southern eclogite blocks bear evidence of their partial melting with the formation of veins and melt percolation channels. The northern eclogite blocks show no evidence of melting. Despite the significant mineralogic difference, both types of eclogites can be assigned to amphibole eclogite facies. The applied jadeite solubility geobarometers yielded the minimum pressures of ∼12 kbar for the northern eclogites and ∼14–14.5 kbar for the southern ones. The used geothermometers yielded ∼700°C and ∼750°C, respectively. But the presence of quartz lamellae in Na-clinopyroxenes in both types of eclogites and their bulk compositions corresponding to high-Mg basalts suggest that the Kuru-Vaara eclogites might have reached the field of ultrahigh-pressure metamorphism. Analysis of the tentative P-T paths of metamorphic evolution for both types of eclogites showed that their burial–exhumation cycle might have taken as short as a few million years. The set of presented data suggests that the formation of the Kuru-Vaara eclogites was related to the subduction of the Archean oceanic crust, which should have differed in composition and structure from the modern oceanic crust.