bluuebunny/crossref_metadata_2025_split huggingface dataset:
Coating of polyelectrolyte multilayer thin films on nanofibrous scaffolds to improve cell adhesion
Authors: Dubas Stephan T. , Kittitheeranun Paveenuch , Rangkupan Ratthapol , Sanchavanakit Neeracha , Potiyaraj Pranut 
Published: June 2009

AbstractThe adhesion of L929 cells to poly(ϵ‐caprolactone) (PCL) nanofibers was successfully improved via coating with polyelectrolyte multilayer thin films (PEMs), which enhanced the potential of this material as a scaffold in tissue engineering applications. With the electrostatic self‐assembly technique, poly(diallyldimethylammonium chloride) (PDADMAC) and poly(sodium 4‐styrene sulfonate) (PSS) were formed as four‐bilayer PEMs on electrospun PCL nanofiber mats. Because PDADMAC and PSS are strong polyelectrolytes, they provided stable films with good adhesion on the fibers within a wide pH range suitable for the subsequent processes and conditions. PDADMAC and gelatin were also constructed as four‐bilayer PEMs on top of the PDADMAC‐ and PSS‐coated nanofibers with the expectation that the gelatin would improve the cell adhesion. L929 cells from mouse fibroblasts were then seeded on both uncoated and coated scaffolds to study the cytocompatibility and in vitro cell behavior. It was revealed by the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay that both the uncoated and coated nanofiber mats were nontoxic as the cell viability was comparable to that of those cultured in the serum‐free medium that was used as a control. The MTT assay also demonstrated that cells proliferated more efficiently on the coated nanofibers than those on the uncoated ones during the 48‐h culture period. As observed by scanning electron microscopy, the cells spread well on the coated nanofibers, especially when gelatin was incorporated. The surface modification of PCL nanofiber mats described in this research is therefore an effective technique for improving cell adhesion. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Surface modification of polycarbonate by radio‐frequency plasma and optimization of the process variables with response surface methodology
Authors: Gomathi N. , Eswaraiah C. , Neogi Sudarsan 
Published: June 2009

AbstractThis study deals with the radio‐frequency plasma treatment of polycarbonate surfaces with argon. The wettability of polycarbonate was examined by static contact angle measurements with polar solvents (deionized water and formamide) and a nonpolar solvent (diiodomethane). The surface free energy of the polycarbonate obtained from the measured contact angle demonstrated that exposure to argon plasma resulted in an increased surface energy and polarity compared to the untreated polycarbonate. Attenuated total reflection/Fourier transform infrared spectroscopy indicated that argon plasma treatment resulted in surface chemistry changes by hydrogen abstraction from the phenyl ring and methyl group and chain scission at the ether and carbonyl sites. These led to the formation of hydroxyl groups and double bonds. With scanning electron microscopy and atomic force microscopy analysis, changes in the surface morphology and roughness before and after plasma treatment were observed. We followed an experimental matrix with the identified process variables affecting the wettability of the polymer, and optimized the experiments with the response surface methodology of a central composite design. A quadratic model was developed to represent the surface energy in terms of process variables. Optimized process conditions were derived from the predicted model and were confirmed by the experimental data at the predicted optimum conditions. The prediction accuracy of the model was found to be very high. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and metal ion adsorption properties of poly(4‐sodium styrene sulfonate‐co‐acrylic acid)
Authors: Rivas Bernabé L. , Muñoz Carla 
Published: June 2009

AbstractThe water‐insoluble resin poly(sodium 4‐styrene sulfonate‐co‐acrylic acid) was synthesized through a solution radical polymerization with ammonium persulfate as an initiator and N,N′‐methylene‐bis‐acrylamide as a crosslinking reagent (CR) at different amounts (2, 4, 6, and 8 mol %). The polymerization yield ranged from 75 to 91%. The metal ion retention properties were studied by batch and column equilibrium procedures for: Cd(II), Cr(III), Zn(II), Al(III), Pb(II), and Hg(II). These properties were investigated under competitive and noncompetitive conditions. The effect of pH, particle size, time, temperature, and initial metal ion concentration on metal ion adsorption was investigated. The resins showed a high retention ability for Hg(II) ions over 85% at pH 2 and for Cd(II), Cr(III), Zn(II), and Pb(II) over 96% at pH 5. The maximum adsorption performance for Pb(II) was achieved as 148.5 mg/g at an optimum pH. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Effect of carboxymethyl cellulose concentration on rheological behavior of milk and aqueous systems. A creep and recovery study
Authors: Bayarri S. , Dolz M. , Hernández M. J. 
Published: June 2009

AbstractCarboxymethyl cellulose (CMC) is an anionic polysaccharide used mainly as stabilizer and thickener agent. The purpose of this study was to investigate the effect of CMC concentration on viscoelasticity of dairy and aqueous model systems through the analysis of creep and recovery tests. The viscoelastic properties of different concentrations of CMC (0.75, 1.00, 1.25, and 1.50% w/w) in two milk systems (skimmed milk and whole milk) were compared with those of the same concentration of biopolymer in aqueous solution. Creep curves were fitted to a six parameter mechanical model (Burger + Kelvin‐Voigt), whereas an empirical equation was used for recovery. The creep and recovery properties of samples were clearly affected by both the type of dispersing media and the CMC concentration. The whole‐milk system was more elastic than both the biopolymer (CMC) aqueous solution and the skimmed‐milk sample, indicating that in whole‐milk samples some new interactions could take place between macromolecules. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Interaction of microcrystalline chitosan (MCCh) with Mo(VI) in aqueous solution
Authors: Kufelnicki Aleksander , Lichawska Marta E. , Bodek Kazimiera H. 
Published: June 2009

AbstractThe molybdenum(VI) complex formation equilibria of microcrystalline chitosan (MCCh) with three different degrees of deacetylation (DD = 0.750, 0.812, and 0.948) were studied by pH‐potentiometric and UV‐spectrophotometric methods. The hydrolysis constants of Mo(VI) were evaluated under exactly the same conditions as during the experiments in presence of chitosan. It has been shown that the complexation model depends on DD. Besides the formation of a ligand to metal 2 : 1 MoO2B22+ complex (“bridge model”) with A = MoO42−, B = MCCh, H = proton, the 1 : 1 MoO3B species (“pendant model”) has been confirmed as well for the two lower values of DD and moderate excess of ligand. At the highest DD, the results indicate only the occurrence of 2 : 1 species. When taking into account the number of protons in reaction as the third index, the corresponding average overall stability constants log βabh of MoO3B and MoO2B22+ reach log β112 = 13.8 and log β124 = 27.9, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Thermal stability eminence of PMMA prepared in presence of photosynthesized ruthenium carbonyl Schiff base as a catalyst
Authors: Youssef Teraze A. , Mekewi Mohamed A. 
Published: June 2009

AbstractSunlight irradiation reaction of Ru3(CO)12 with a Schiff base, bis (acetyl acetone) ethylene diimine, acacenH2, in benzene results in the formation of an octahedral complex [Ru(CO)2(acacen)] with a tetradentate ligand. The complex was structurally confirmed using elemental analysis, infrared, mass spectrometry, 1HNMR, UV–vis absorption spectra, and magnetic measurements. [Ru(CO)2(acacen)] complex compound was then used as a catalyst for the polymerization of methyl methacrylate (MMA) in the presence of sodium bisulfite as a cocatalyst. FT‐IR, gel permeation chromatography (GPC) was used as a tool for structure confirmation and molecular weights of the poly methyl methacrylate (PMMA). The stability of the catalyzed polymer against thermal degradation was investigated using thermal gravimetric analysis (TGA) and differential thermal analysis (DTA) to assess its distinctive thermal stability. Higher thermal stability of PMMA samples prepared in presence of [Ru(CO)2(acacen)] compared with blank PMMA were clearly observed. A reaction mechanism was suggested based on the coordination of the complex compound with the polymeric chains. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Thermal degradation and flammability of P/Si polysilsesquioxane epoxy nanocomposites
Authors: Chiu Yie‐Chan , Ma Chen‐Chi M. , Liu Fang‐Yi , Chou I‐Chen , Chiang Chin‐Long , Yang Jeng‐Cheng 
Published: June 2009

AbstractA thermal stable epoxy nanocomposite prepared from the 4,4′‐diglycidylether bisphenol A (DGEBA) and the P/Si ladder‐like polysilsesquioxane (PSSQ). The activation energies of thermal degradation were calculated by Kissinger's and Ozawa's methods. The higher ladder‐like PSSQ content not only increase the oligomer content but also generate the steric hindrance. Which steric hindrance influence the epoxy/amine curing reaction of the modified epoxy system was more than the pristine DGEBA epoxy system. The P‐Si synergistic effect on the thermal stability of the nanocomposites was discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Conductive plastics with hybrid materials
Authors: Immonen Kirsi , Nättinen Kalle , Sarlin Juha , Hartikainen Juha 
Published: June 2009

AbstractHybrid materials of conducting polyaniline (PANi) and multiwalled carbon nanotubes (CNTs) were synthesized using an in situ polymerization method. The resulting CNTs with a thin layer of PANi coating were further compounded with polypropylene to produce electrically conductive composite material. The PANi coating was found to enhance the CNT dispersion in PP. An amphiphilic component was also used as a surfactant to further enhance the dispersion. With these methods and materials, a conductivity of 26 S cm−1 was obtained. The conductivity of the hybrid material far exceeded that of the separately compounded mixture and of that prepared of lower aspect ratio conductive materials: carbon nanofibers and carbon black. The level of conductivity qualifies the material for use in applications requiring electromagnetic interference shielding. By adjusting the PANi loading, the conductivity can be tuned down to obtain materials suitable for electrostatic discharge applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Structure‐rheology responses of polylactide/calcium carbonate composites
Authors: Gu Shu‐Ying , Zou Cun‐Yang , Zhou Kai , Ren Jie 
Published: June 2009

AbstractPolylactide (PLA) and calcium carbonate (CaCO3) were melt blended using a twin‐screw extruder. The morphology of PLA/CaCO3 composites was observed by scanning electronic microscopy. The linear and nonlinear shear rheological behaviors of PLA/CaCO3 melts were investigated by an advanced rheology expended system. The results show that the CaCO3 particles are evenly dispersed in the PLA matrix. The incorporation of low CaCO3 content (<20%) causes the reduction of the storage moduli, loss moduli, and dynamic viscosities whereas high CaCO3 content (>30%) leads to the increase of the storage moduli, loss moduli, and dynamic viscosities. The composites with high CaCO3 content show pseudo‐solid‐like behaviors at low frequency. High CaCO3 content also results in a significant increase of flow activation energy and a dramatic decrease of flow index n, which is in consistent with the more serious shear‐thinning tendency of high‐filled PLA composites melts. The particular rheological responses might be attributed to the formation and destruction of the percolating network. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Additive effect of poly(ethylene oxide) on polypropylene/fibrous cellulose composite: Effects of additive amount of poly(ethylene oxide) on Young's modulus and morphology
Authors: Miyazaki Kensuke , Nakatani Hisayuki 
Published: June 2009

AbstractIn this work, the additive effects of the poly(ethylene oxide) (PEO) on the Young's moduli of two kinds of polypropylene (PP)/fibrous cellulose (FC) composite were studied using the Kerner–Nielsen equation. In the case of the PP/maleated PP (MAPP)/FC + PEO composite, all the values of the moduli with the various PEO contents were in good agreement with the theoretical values obtained from the Kerner–Nielsen equation. Whereas the moduli of the PEO/FC + PP/MAPP composite followed the Kerner–Nielsen equation about 6 vol % of the PEO content and then unexpectedly deviated. In the scanning electron microscopy (SEM) observation, the PP/MAPP/FC + PEO composite was found to have a sea‐island morphology corresponding to the PP/MAPP/FC matrix and the PEO phase. This morphology had been unchanged against the increase of the PEO content. Whereas in the case of the PEO/FC + PP/MAPP composite, the SEM micrographs showed that that the interface between the FC and the PP became worse with the increase of the PEO content, indicating that the formation of the PP/MAPP/FC matrix was blocked by the excess PEO. The deviation of the Young's moduli from the Kerner–Nielsen equation was due to the blocking of the PEO. It was found that the adequate combination of the PEO and the MAPP was able to supply the increase of the toughness of the PP/FC composite by investigating the dependence of the PEO/FC + PP/MAPP composite on the MAPP content. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Thiol containing sulfonamide based polymeric sorbent for mercury extraction
Authors: Yavuz Erdem , Barim Gamze , Senkal Bahire Filiz 
Published: June 2009

AbstractA new polymeric resin with thiol pendant functions has been prepared for the extraction of mercuric ions. The thiol containing sulfonamide based resin with 3.5 mmol/g total nitrogen content is able to selectively sorb mercury from aqueous solutions. The mercury sorption capacity of the resin is around 1.70 mmol/g under non‐buffered conditions. Experiments performed in identical conditions with several metal ions revealed that Cd(II), Pb(II), Zn(II), Fe(III), and Fe (II) ions also were extractable in quantities (1.0–1.65 mmol/g). The sorbed mercury can be eluted by repeated treatment with 4M HNO3 without hydrolysis of the amide groups. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Trabecular Microarchitecture of Hominoid Thoracic Vertebrae
Authors: Cotter Meghan M. , Simpson Scott W. , Latimer Bruce M. , Hernandez Christopher J. 
Published: June 2009

AbstractSpontaneous vertebral fractures are a common occurrence in modern humans, yet these fractures are not documented in other hominoids. Differences in vertebral bone strength between humans and apes associated with trabecular bone microarchitecture may contribute to differences in fracture incidence. We used microcomputed tomography to examine trabecular bone microarchitecture in the T8 vertebra of extant young adult hominoids. Scaled volumes of interest from the anterior vertebral body were analyzed at a resolution of 46 μm, and bone volume fraction, trabecular thickness, trabecular number, trabecular separation, structure model index, and degree of anisotropy were compared among species. As body mass increased, so did trabecular thickness, but bone volume fraction, structure model index, and degree of anisotropy were independent of body mass. Bone volume fraction was not significantly different between the species. Degree of anisotropy was not significantly different among the species, suggesting similarity of loading patterns in the T8 vertebra due to similar anatomical and postural relationships within each species' spine. Degree of anisotropy was negatively correlated with bone volume fraction (r2 = 0.85, P < 0.05) in humans, whereas the apes demonstrated no such relationship. This suggested that less dense human trabecular bone was more preferentially aligned to habitual loading. Furthermore, we theorize that trabeculae in ape thoracic vertebrae would not be expected to become preferentially aligned if bone volume fraction was decreased. The differing relationship between bone volume fraction and degree of anisotropy in humans and apes may cause less dense human bone to be more fragile than less dense ape bone. Anat Rec, 2009. © 2009 Wiley‐Liss, Inc.
New and improved: The role of text augmentation and the application of response interpretation standards (coding schemes) in a final iteration of birth defects warnings development
Authors: Mayhorn Christopher B. , Goldsworthy Richard C. 
Published: June 2009

AbstractBACKGROUND:Several birth defects warning symbols identified as most successful in an earlier study (Mayhorn and Goldsworthy, 2007) were further modified and then evaluated within a nationally distributed field trial (n = 2773). The purpose for the current research was to determine whether symbol warning components could be improved further, whether the addition of text enhanced comprehension uniformly across symbols, and whether results varied by the application of different interpretation standards (coding schemes).METHOD:A total of 11 warning labels were examined: four new symbols plus the existing baseline symbol, each in versions with and without text, plus a text‐only condition. Participant interpretation accuracy and preferences were assessed during face‐to‐face interview sessions.RESULTS:For symbol‐only conditions, several candidate symbols outperformed the existing symbol, one substantially so. The effect of adding text to symbols varied significantly by symbol. Symbol plus text and text‐only conditions performed equivalently, generally exceeded symbol‐only conditions, and often surpassed the American National Standards Institute benchmark of 85% accurate interpretation.CONCLUSIONS:The research effort has identified a teratogen symbol and warning that outperforms the one currently in use. The effort has also identified important pragmatic and conceptual issues that should inform future work to improve medication labeling and other hazard communication. Birth Defects Research (Part A), 2009. © 2009 Wiley‐Liss, Inc.
The influence of pulsed magnetic fields (PMFs) on nonsynaptic potentials recorded from the central and peripheral nervous systems in vitro
Authors: Ahmed Zaghloul , Wieraszko Andrzej 
Published: June 2009

AbstractThe influence of pulsed magnetic fields (PMFs) on nonsynaptic potentials recorded from the central and peripheral nervous system in vitro has been investigated. The population spikes (PSs) recorded from hippocampal slices during antidromic stimulation and compound action potentials (CAPs) recorded from the segments of the sciatic nerve were used as indicators of neuronal activity. The potentials recorded from both preparations were significantly and permanently enhanced following PMF (0.16 Hz, 15 mT) exposure. The increase in the antidromic PS occurred even in the presence of potassium channel blocker tetraethylammonium (TEA) and was accompanied by multiple spiking. Among all frequencies of PMF tested (0.5, 0.16, 0.07, 0.03, 0.0 Hz), the frequency of 0.5 Hz was the most effective in enhancement of potential amplitude. The influence of PMF on the amplitude of two CAPs evoked by the pair of electrical stimuli applied in rapid succession has also been evaluated. In control conditions the potential triggered by the second stimuli was slightly smaller expressing the phenomenon of short‐term depression (STD). Although PMF exposure amplified the amplitude of both potentials, the increase in the size of the first potential was significantly greater increasing further the magnitude of STD. The blocking of potassium channels reversed STD into facilitation. One of the possible mechanisms involved in PMF action could be the modification of the axonal threshold, which was significantly reduced following exposure to PMF. Bioelectromagnetics 30:621–630, 2009. © 2009 Wiley‐Liss, Inc.
Hypersensitivity to RF fields emitted from CDMA cellular phones: A provocation study
Authors: Nam Ki Chang , Lee Ju Hyung , Noh Hyung Wook , Cha Eun Jong , Kim Nam Hyun , Kim Deok Won 
Published: June 2009

AbstractWith the number of cellular phone users rapidly increasing, there is a considerable amount of public concern regarding the effects that electromagnetic fields (EMFs) from cellular phones have on health. People with self‐attributed electromagnetic hypersensitivity (EHS) complain of subjective symptoms such as headaches, insomnia, and memory loss, and attribute these symptoms to radio frequency (RF) radiation from cellular phones and/or base stations. However, EHS is difficult to diagnose because it relies on a person's subjective judgment. Various provocation studies have been conducted on EHS caused by Global System for Mobile Communications (GSM) phones in which heart rate and blood pressure or subjective symptoms were investigated. However, there have been few sham‐controlled provocation studies on EHS with Code Division Multiple Access (CDMA) phones where physiological parameters, subjective symptoms, and perception of RF radiation for EHS and non‐EHS groups were simultaneously investigated. In this study, two volunteer groups of 18 self‐reported EHS and 19 non‐EHS persons were tested for both sham and real RF exposure from CDMA cellular phones with a 300 mW maximum exposure that lasted half an hour. We investigated not only the physiological parameters such as heart rate, respiration rate, and heart rate variability (HRV), but also various subjective symptoms and the perception of EMF. In conclusion, RF exposure did not have any effects on physiological parameters or subjective symptoms in either group. As for EMF perception, there was no evidence that the EHS group better perceived EMF than the non‐EHS group. Bioelectromagnetics 30:641–650, 2009. © 2009 Wiley‐Liss, Inc.
Polycomb group proteins: remembering how to catch chromatin during replication
Authors: Kumar Ram Parikshan 
Published: June 2009

AbstractPolycomb group (PcG) proteins maintain the expression state of PcG‐responsive genes during development of multicellular organisms. Recent observations suggest that “the H3K27me3 modification” acts to maintain Polycomb repressive complex (PRC) 2, the enzyme that creates this modification, on replicating chromatin. This could in turn promote propagation of H3K27me3 on newly replicated daughter chromatin, and promote recruitment of PRC1. Other work suggests that PRC1‐class complexes can be maintained on replicating chromatin, at least in vitro, independently of H3K27me3. Thus, histone modifications and PcG proteins themselves may both be maintained through replication.