bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of Poly(vinyl alcohol)/Chitosan Hydrogels as Vascular Tissue Engineering Scaffolds
Authors: Vrana Nihal Engin , Liu Yurong , McGuinness Garret Brian , Cahill Paul Aidan 
Published: August 2008

AbstractIn this study, PVA/Chitosan hydrogels were fabricated by freeze/thaw cycles and further crosslinking with a KOH/Na2SO4 coagulation bath and the effect of freeze/thaw cycle number on cell behaviour was evaluated. The surface of the hydrogels were further modified with Collagen type I adsorption and seeded with bovine aortic vascular smooth muscle and endothelial cells. Increasing the number of freeze/thaw cycles resulted in a marked change in surface morphology, hydrophilicity and protein adsorption. Collagen coating caused an increase in initial attachment and proliferation. We concluded that hydrogels that have undergone 3 freeze/thaw cycles were optimum for cell attachment both in the presence and the absence of coating.
Novel Biologically Inspired Collagen Nanofibers Reconstituted by Electrospinning Method
Authors: Foltran Ismaela , Foresti Elisabetta , Parma Bruna , Sabatino Piera , Roveri Norberto 
Published: August 2008

AbstractThe possibility to prepare bioinspired collagen nanofibers by electrospinning from aqueous suspension of telopeptide‐free collagen molecules avoiding both organic solvents and blends with any synthetic and natural polymers has been investigated. The results have highlighted the need for a basic atmosphere between the needle and the ground collector in order to increase the environmental pH during the collagen molecules self‐assembly along the electrostatic force lines. Morphological, spectroscopic and calorimetric analyses carried out on the electrospun collagen nanofibers have opened the possibility to take advantage of this new approach in order to prepare an ideal biomimetic reinforcing component of new biomedical and surgical biomaterials.
Phospholipids Bilayers as Molecular Models for Drug‐ Membrane Interactions. The Case of the Antiepileptics Phenytoin and Carbamazepine
Authors: Suwalsky Mario , Mennickent Sigrid , Villena Fernando , Sotomayor Carlos P. 
Published: August 2008

AbstractWith the aim to better understand the molecular mechanisms of the interaction of phenytoin and carbamazepine with cell membranes we utilized a well‐established model consisting in intact human erythrocytes, isolated unsealed human erythrocyte membranes (IUM) and molecular models of its membrane. The latter consisted of bilayers of dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidyl‐ethanolamine (DMPE), representative of phospholipid classes respectively located in the outer and inner monolayers of erythrocytes and other cell membranes. This report presents the following evidence that phenytoin and carbamazepine interact with membrane phospholipids: a) X‐ray diffraction and fluorescence spectroscopy showed that both drugs preferentially interacted with DMPC; b) in IUM, the drugs induced a disordering effect on the polar head groups and acyl chains of the eryhrocyte membrane lipid bilayers; c) electron microscopy observations of human erythrocytes showed the echinocyte formation, an effect due to phenytoin and carbamazepine insertion in the outer monolayer of the red cell membrane.
Influence of Oxygen Plasma Modification on Surface Free Energy of PMMA Films and Cell Attachment
Authors: Ozcan Canturk , Zorlutuna Pınar , Hasirci Vasıf , Hasirci Nesrin 
Published: August 2008

AbstractFor any biomaterial placed into a biological medium, the surface properties of the material, such as porosity, crystallinity, presence and distribution of electrical charge and functional groups are very critical parameters that determine the acceptance or rejection of the material. Applications, especially tissue engineering require some surface modifications at the molecular level without disturbing the bulk properties of the implants in order to enhance the cell attachment on the material. An appropriate technique is the application of glow discharge plasma which employs no solvents, takes place at ambient temperatures, and alterations take place only at the surface by changing the surface chemistry along with surface free energy (SFE) and efficiency for cell‐material interaction. In this study, poly(methyl methacrylate) (PMMA) film surfaces were modified with oxygen plasma. SFE and its dispersive and polar (acidic‐basic) components of the modified surfaces were calculated by means of several theoretical approaches including geometric mean, harmonic mean and acid‐base equations. The relation between SFE and its dispersive and polar components and cell attachment on surfaces were studied. The highest 3T3 cell attachment was obtained for the surface with the total SFE of 61.77 mJ/m2 and polar component of 50.91 mJ/m2 according to Geometric mean. The total SFE of this surface was calculated to be 61.06 mJ/m2 and the polar component as 40.96 mJ/m2 using the Harmonic mean method.
Surface Modification of Polyurethanes with Covalent Immobilization of Heparin
Authors: Aksoy Ayse E , Hasirci Vasif , Hasirci Nesrin 
Published: August 2008

AbstractThrombus formation and blood coagulation is a major problem associated with blood contacting products such as catheters, vascular grafts, arteries, artificial hearts and heart valves. An intense research is being conducted towards the synthesis of new hemocompatible materials and modifications of surfaces with biological molecules. In this study, polyurethane (PU) films were synthesized in medical purity from diisocyanate and polyol without using any other ingredients and their surfaces were modified by covalent immobilization of heparin. Two types of heparin, unfractionated (UFH) and low molecular weight heparin (LMWH), were immobilized to investigate their effect on cell adhesion. The surface properties of the modified PUs were examined with ESCA, ATR‐FTIR and AFM. ESCA results demonstrated sulfur peaks indicating the presence of heparin and AFM results showed the alteration of surface structure after coating with heparin. Cell adhesion studies were conducted with heparinized whole human blood. The surfaces of the UFH immobilized films resulted in lesser red blood cell adhesion in comparison to LMWH demonstrating strong anti‐thrombogenic activity of the latter.
Autooxidized Polyunsaturated Oils/Oily Acids: Post‐it Applications and Reactions with Fe(III) and Adhesion Properties
Authors: Keleş Elif , Hazer Baki 
Published: August 2008

AbstractSoybean oil, sesame oil, linoleic acid and linolenic acid were epoxidized, peroxidized and hydroperoxidized via autooxidation under air oxygen and sunlight at room temperature to obtain novel post‐it materials. Polymeric soybean oil peroxide and sesame oil peroxide were containing soluble part of 60%(w/w) together with crosslinked part of 40%(w/w) while polymeric linoleic and polymeric linolenic acids were completely soluble. The autooxidized soluble products with Mn varying between 800 and 3100 Daltons were used as post‐it adhesive. The highest adhesion was observed in the case of polymeric soybean oil (3.0 Newton), while adhesion of commercial epoxidized soybean oil, polymeric linoleic and polymeric linolenic acid were 0.8, 0.5 and 0.5 Newton, respectively. Reactions of the autooxidized soluble products with Fe(NO3)3. 4H2O in the presence of ethanol, glycerol and diethyleneglycol gave the hydroxy functionalized products with the same Mn values and indicating no adhesive properties. When the commercial epoxidized soybean oil was reacted with Fe(NO3)3. 4H2O in the presence of the alcohols, Mn of the hydroxy functionalized polymeric oil was found to be unchanged. 1H NMR, FT‐IR, SEM and GPC techniques were used in the characterization of the products obtained.
Post Polymerization of Saturated and Unsaturated Poly(3‐hydroxy alkanoate)s
Authors: Erduranlı Haydar , Hazer Baki , Borcaklı Mehlika 
Published: August 2008

AbstractSummary: Chemical modification is useful to diversify poly(3‐hydroxyalkanoate)s, for medical and industrial applications. In this manner, transesterification reactions of poly(3‐hydroxy butyrate) were carried out under reflux condition of 1,2‐dichlorobenzene in the presence of 1,4‐butane diol, poly(ethylene glycol) bis(2‐aminopropyl ether) with molecular weights of 1000 and 2000, poly(ethylene glycol)methacrylate or glycerol at 180 °C. Addition reactions of bromine and –SH groups of 3‐mercaptopropionic acid to the double bond of poly(3‐hydroxy‐10‐undecenoate) were also carried out. Functionalized poly(3‐hydroxyalkanoate)s were characterized using 1H NMR, FTIR, GPC and thermal analysis techniques.
Structure elucidation and NMR spectral assignments of four neolignan glycosides with enantiometric aglycones from Osmanthus ilicifolius
Authors: Machida Koichi , Sakamoto Shigeaki , Kikuchi Masao 
Published: August 2008

AbstractFour new 8‐O‐4′ type neolignan glycosides with enantiometric aglycones, (7S,8R)‐erythro‐guaiacylglycerol‐β‐O‐4′‐sinapyl ether 9‐O‐β‐D‐glucopyranoside (1), (7R,8S)‐erythro‐guaiacylglycerol‐β‐O‐4′‐sinapyl ether 9‐O‐β‐D‐glucopyranoside (2), (7S,8R)‐erythro‐ syringylglycerol‐β‐O‐4′‐sinapyl ether 9‐O‐β‐D‐glucopyranoside (3) and (7R,8S)‐erythro‐ syringylglycerol‐β‐O‐4′‐sinapyl ether 9‐O‐β‐D‐glucopyranoside (4), were isolated from the leaves of Osmanthus ilicifolius. Their structures were established on the basis of NMR, circular dichroism (CD), MS and chemical data. The NMR assignments for the compounds were carried out using 1H, 13C, COSY, HMQC, HMBC and NOESY NMR experiments. Copyright © 2008 John Wiley & Sons, Ltd.
hp‐Generalized FEM and crack surface representation for non‐planar 3‐D cracks
Authors: Pereira J. P. , Duarte C. A. , Guoy D. , Jiao X. 
Published: August 2008

AbstractA high‐order generalized finite element method (GFEM) for non‐planar three‐dimensional crack surfaces is presented. Discontinuous p‐hierarchical enrichment functions are applied to strongly graded tetrahedral meshes automatically created around crack fronts. The GFEM is able to model a crack arbitrarily located within a finite element (FE) mesh and thus the proposed method allows fully automated fracture analysis using an existing FE discretization without cracks. We also propose a crack surface representation that is independent of the underlying GFEM discretization and controlled only by the physics of the problem. The representation preserves continuity of the crack surface while being able to represent non‐planar, non‐smooth, crack surfaces inside of elements of any size. The proposed representation also provides support for the implementation of accurate, robust, and computationally efficient numerical integration of the weak form over elements cut by the crack surface. Numerical simulations using the proposed GFEM show high convergence rates of extracted stress intensity factors along non‐planar curved crack fronts and the robustness of the method. Copyright © 2008 John Wiley & Sons, Ltd.
Combined modification of asphalt by waste PE and rubber
Authors: Fang Changqing , Li Tiehu , Zhang Zengping , Wang Xin 
Published: August 2008

AbstractWaste PE (WPE) and rubber were combined to modify the ordinary oil asphalt in order to improve the performance of asphalt. In this study, the recycled waste packing polymer replacing the ordinary polymer modifiers modified the road asphalt through mechanical mixing for the first time. Results showed that softening point and ductility of asphalt increased, while the penetration degree decreased after the modification. The overall performance of the asphalt/WPE/RU system was superior to that of the asphalt/WPE system. FT‐IR analysis indicated that the modification actually was a physical process. The microstructure of the modified asphalt indicated that the shear yield and crack‐branching caused by the waste rubber powder were the main reasons for the improvement of the performance of asphalt. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers
A fatigue damage model for composite materials
Authors: Chen Hsing‐Sung , Hwang Shun‐Fa 
Published: August 2008

AbstractComposite materials using polymer resins as matrices possess viscoelastic properties such that the fatigue behavior of the composite could be changed by different stress levels, stress ratio, stress frequency, or temperature. Based on a physical phenomenon of damage growth, this work develops a fatigue damage model including the nonlinear effects of stress ratio and stress frequency on the damage processes for carbon/epoxy composites. A damage index is defined and used to confirm the damage evolution behavior, and a series of fatigue tests of unidirectional specimens under monotonous loading and two‐stress level loading are conducted to test the proposed fatigue damage model. The results reveal that the proposed model could reasonably predict the fatigue life of composite materials under complicated loading conditions and it also includes the sequence effect of cyclic block loadings. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Grafting of polystyrene chains on surfaces of nanosilica particles via peroxide bulk polymerization
Authors: Suckeveriene R.Y. , Tzur A. , Narkis M. , Siegmann A. 
Published: August 2008

AbstractThis article describes an in situ bulk polymerization process of styrene in the presence of silica nanoparticles. In this peroxide bulk polymerization process, two polystyrene fractions are formed: A polystyrene (PS) fraction attached to the particle's surface, which cannot be detached by hot xylene extraction, and an unattached PS fraction which dissolves in xylene. Solvent extraction and TGA measurements have confirmed the existence of grafted PS chains to the silica surfaces. FTIR measurements have indicated the existence of SiOC bonds connecting the PS grafts to the silica surface. Polypropylene (PP) was blended with the extracted PS‐g‐silica particles to produce concentrations of 1–3% nanoparticles in the PP composites. A remarkably improved dispersability of the nanoparticles was achieved, thus grafting reduces re‐agglomeration and increases the affinity of the grafted surface to the polymer matrix. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Preparation and insulation property studies of thermoplastic PMMA‐silica nanocomposite foams
Authors: Yeh J.M. , Chang K.C. , Peng C.W. , Chand B.G. , Chiou S.C. , Huang H.H. , Lin C.Y. , Yang J.C. , Lin H.R. , Chen C.L. 
Published: August 2008

AbstractThe comparative studies for the effect of vinyl‐modified silica (VMS) and raw silica (RS) particles on the cell structure, insulation (dielectric and thermal transport) properties, and thermal stability of thermoplastic PMMA‐silica nanocomposite (PSN) foams are described. The VMS particles were synthesized by the conventional acid‐catalyzed sol‐gel reactions of tetraethyl orthosilicate (TEOS) in the presence of 3‐(trimethoxysilyl)propyl methacrylate (MSMA) molecules. The as‐prepared VMS particles were then characterized through fourier transform infrared (FTIR), solid‐state 13C‐nuclear magnetic resonance (13C‐NMR) and 29Si‐NMR spectroscopy. Subsequently, the PSN materials were prepared via in‐situ bulk polymerization. The dispersion of silica particles in PMMA matrix was observed by transmission electron microscopy (TEM) studies. Gel permeation chromatography (GPC) was used to determine the molecular weights of as‐prepared samples. The PSN materials were used to produce foams by a batch process in an autoclave using nitrogen as foaming agent. The effect of VMS and RS particles on the cell structure, insulation properties and thermal stability of PSN foams were investigated by scanning electron microscopy (SEM), LCR meter, Transient plane source (TPS) technique and thermal gravimetric analysis (TGA), respectively. The better dispersion capability of VMS particles in PSN foams was found to lead enhanced nucleation efficiency, thermal stability and decreased dielectric constant (ε′), dielectric loss (ε″) and thermal conductivity (k). POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Improving the properties of LDPE/glass fiber composites with silanized‐LDPE
Authors: Fabris Felipe W. , Cardozo Nilo S.M. , Mauler Raquel S. , Nachtigall Sônia M.B. 
Published: August 2008

AbstractLow density polyethylene (LDPE) is a widely used thermoplastic. The dispersion of inorganic fillers in thermoplastic matrices such as polyethylene has been largely employed to improve some of its properties. However, interaction between both components is a major issue so the presence of a coupling agent is usually necessary to increase the interaction among the phases. In this study, LDPE chemically modified with vinyltriethoxysilane (VTES) was used as a coupling agent in glass fiber‐reinforced LDPE. The composites were prepared in a mixing chamber and subsequently analyzed by tensile tests, rotational rheometry, and scanning electron microscopy (SEM). The mechanical properties were significantly increased by the use of small amounts of the coupling agent. Moreover, the rheological behavior and the SEM micrographs showed higher interaction between the matrix and the reinforcing phase in the composites containing LDPE modified with VTES, confirming the suitability of using this coupling agent in these systems. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Biodegradable nanocomposites from maleated polycaprolactone/soy protein isolate blend with organoclay: Preparation, characterization, and properties
Authors: Sasmal Abhisek , Sahoo Debasish , Nanda Rajashree , Nayak Preetishree , Nayak Padma L. , Mishra Joy K. , Chang Young‐Wook , Yoon Joon‐Yong 
Published: August 2008

AbstractNew biobased, eco‐friendly nanocomposites were prepared from maleated polycaprolactone/soy protein isolate blend (50/50 wt/wt) with organo‐modified clay by melt compounding. The XRD, TEM, tensile, DMTA, and rheological properties of the nanocomposites were investigated. X‐ray diffraction and transmission electron microscopy analysis revealed that the intercalated nanocomposite is formed and the silicate layers of the clay are uniformly dispersed at a nanometer scale in the polymer matrix. There is a great enhancement in tensile and dynamic mechanical properties of the nanocomposites. Rheological study revealed that the nanocomposite exhibits strong shear thinning behavior and clay particles form network in the melted state of the composites. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Maleated polypropylene film and wood fiber handsheet laminates
Authors: Lee Sangyeob , Shupe Todd F. , Groom Leslie H. , Hse Chung Y. 
Published: August 2008

AbstractThe grafting effect of maleic anhydride (MA) as an interfacial bonding agent and its influence on the tensile strength properties of thermomechanical pulp handsheet‐isotactic polypropylene (iPP) film laminates was studied. For the MA treated with benzoyl peroxide (BPO) as an initiator, tensile strength properties increased 76% with PP film over untreated laminates. The optimal strength properties were obtained with a MA and BPO ratio of 2:1. A strong correlation was observed between the number of fibers in the web and tensile strength properties for both handsheet drying conditions. The R2 values were 0.95 for air‐dry conditions and 0.94 from oven‐dry conditions. Scanning electron microscopy images also showed the effectiveness of MA loading on the surface of thermomechanical pulp fibers due to increased fiber failure, which occurred without fiber being pulled out from the PP matrixes. Crystallinity and heat flow were determined using differential scanning calorimetry (DSC) and increased as expected as the ratio of MA and BPO increased from 0:0 to 2:1. These results were also in accordance with the morphological observations at the fracture surface, Fourier transform infrared spectra, and thermal analysis. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Hospitalization for peptic ulcer and bleeding in users of selective COX‐2 inhibitors and nonselective NSAIDs with special reference to celecoxib
Authors: Patterson M. Kay , Castellsague Jordi , Walker Alexander M. 
Published: August 2008

AbstractPurposeTo assess the relative incidence of peptic ulcer bleeding and perforation (PUBP) in users of selective cyclooxygenase‐2 (COX‐2) inhibitors and nonselective nonsteroidal anti‐inflammatory drugs (NSAIDs).MethodsThis was a retrospective case–control study based on insurance claims, with chart review to confirm cases. The base population consisted of 2.2 million adult users of celecoxib, diclofenac, ibuprofen, naproxen, rofecoxib, or valdecoxib who were covered by commercial health insurance in the United States from 1999–2003. For 790 persons hospitalized for PUBP and 7887 controls, most recent NSAID/COX‐2 use and a variety of medical and pharmacy risk factors were ascertained from the insurance files and analyzed by conditional logistic regression. The main outcome measure was the odds ratio (OR) associated with use of each drug by comparison to naproxen, and in successive intervals after last dispensing.ResultsHospitalization for PUBP was highest from the date of NSAID/COX‐2 dispensing through the end of an exposure period that corresponded to the days supply; the rate dropped steadily thereafter. The covariate‐adjusted ORs by comparison to naproxen were: ibuprofen 0.86 (95% confidence interval (CI) 0.68, 1.09), rofecoxib 0.79 (0.62, 1.02), diclofenac 0.66 (0.47, 0.94), valdecoxib 0.50 (0.26, 0.97), and celecoxib 0.45 (0.35, 0.58). The nonselective NSAIDs had an OR for PUBP of 1.51 (1.26, 1.98) compared to the selective COX‐2 inhibitors.ConclusionNonselective NSAIDs convey half again as much risk of hospitalization for PUBP as do COX‐2 inhibitors. Celecoxib users had about half the hospitalization rate of users of naproxen. Copyright © 2008 John Wiley & Sons, Ltd.
‘Yours is potentially serious but most of these are cured’: optimistic communication in UK outpatient oncology consultations
Authors: Leydon Geraldine M. 
Published: August 2008

AbstractObjective: To describe how experienced doctors discuss radiotherapy and chemotherapy with cancer patients about to undergo such treatment.Methods: Qualitative analysis of 27 consultations between consultant oncologists and patients with breast, head, and neck cancer or gastrointestinal cancer. Set in outpatient oncology clinics: one in the South West, one in the Midlands, and a large London teaching hospital. Participants included three experienced consultant oncologists and 27 patients diagnosed with cancer attending outpatient oncology consultations to discuss radiotherapy or chemotherapy.Results: Doctors repeatedly invoked optimism when discussing bad and uncertain information about radiotherapy and chemotherapy. This was achieved by following relatively bad or uncertain information with some good information. Patients tended to collaborate in the construction of optimism.Conclusions: Doctors talked optimistically while sharing information about chemotherapy and radiotherapy with patients about to undergo such treatment. Research indicates that patients want their doctors to openly share bad and uncertain information, but to do so sensitively. Following uncertain or bad tidings with relatively better news was one way in which doctors delivered information honestly without diminishing opportunities for hope in the consultation room or optimism about the future. Findings from qualitative empirical studies, such as that described, provide a valuable educational adjunct to the role play and simulated patient interactions, often used in conventional communication skills training and research. Copyright © 2008 John Wiley & Sons, Ltd.