bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of low‐intensity pulsed ultrasound on the expression of neurotrophin‐3 and brain‐derived neurotrophic factor in cultured Schwann cells
Authors: Zhang Hua , Lin Xin , Wan Hong , Li Jun‐Hua , Li Jia‐Mou 
Published: March 2009

AbstractIt is generally known that low‐intensity pulsed ultrasound (LIPUS) accelerates peripheral nerve tissue regeneration. However, the precise cellular mechanism involved is still unclear. The purpose of this study was to determine how the Schwann cells respond directly to LIPUS stimuli. Thus, we investigated the effect of LIPUS on cell proliferation, neurotrophin‐3 (NT‐3), and brain‐derived neurotrophic factor (BDNF) mRNA expression in rat Schwann cells. Schwann cells were enzymatically isolated from postnatal 1–3 day rat sciatic nerve tissue and cultured in the six‐well plate. The ultrasound was applied at a frequency of 1 MHz and an intensity of 100 mW/cm2 spatial average temporal average for 5 minutes/day. The control group was cultured in the same way but without the administration of ultrasound. Immunohistochemistry demonstrated that more than 98% of the experimental and control cells were positive for S‐100, NT‐3, and BDNF. With 5‐bromo‐2′‐deoxyuridine (BrdU) assay, the stimulated cells also exhibited an increase in the rate of cell proliferation on days 4, 7, 10, and 14. Further investigation found that mRNA expression of NT‐3 was significantly upregulated in experimental groups compared with the control 14 days after the LIPUS stimulation (the ratio of NT‐3/β‐actin was 0.56 ± 0.13 vs. 0.41 ± 0.09, P < 0.01), whereas the mRNA expression of BDNF was significantly downregulated in experimental groups compared with the control (the ratio of BDNF/β‐actin was 0.51 ± 0.05 vs. 0.60 ± 0.08, P < 0.05). These results demonstrated that the application of LIPUS promotes cell proliferation and NT‐3 gene expression in Schwann cells, and involved in the alteration of BDNF gene expression. © 2009 Wiley‐Liss, Inc. Microsurgery, 2009.
Three‐dimensional reconstruction and visualization of the median nerve from serial tissue sections
Authors: Sun Kuo , Zhang Jian , Chen Tongyi , Chen Zhongwei , Chen Zenggan , Li Zhi , Li Hua , Hu Ping 
Published: March 2009

AbstractThe purpose of this study was to definitively implement the three‐dimensional visualization of sensory and motor fascicles in the human median nerve by means of acetylcholinesterase (AChe) histochemical staining and under the assistance of the computer technology. One fresh human median nerve was harvested from a male adult cadaver. The median nerve was fixed at a special holder. Then, the whole holder was embedded and rapidly frozen in the liquid nitrogen. The processed median nerve was then cut coronally every 100 μm at a 20 μm thickness along its long axis in a sliding freezing microtome. The total number of sections was 4,650 slices. All sections were stained with the AChe histochemical method. The stained sections were scanned and saved as Joint Photographic Experts Group files. These images with positively and negatively stained sections were acquired to an Intel dual Pentium computer. The Adobe Photoshop CS2 software was used to compare the reference points of images before and after staining. The two‐dimensional intraneural microstructure database of median nerve was then acquired. A software of 3D nerve visualization system was developed. With the 3D nerve visualization system, the 3D visualization result of intraneural microstructure of median nerve was created. The findings may provide more accurate and detailed anatomic information for nerve repairs, specifically for the fascicular nerve repairs. The 3D nerve visualization technique may have potential for future studies of topography of peripheral nerve. © 2009 Wiley‐Liss, Inc. Microsurgery, 2009.
Global regular solutions to Cahn–Hilliard system coupled with viscoelasticity
Authors: Pawłow Irena , Zaja̧czkowski Wojciech M. 
Published: March 2009

AbstractIn this paper we prove the existence and uniqueness of a global in time, regular solution to the Cahn–Hilliard system coupled with viscoelasticity. The system arises as a model, regularized by a viscous damping, of phase separation process in a binary deformable alloy quenched below a critical temperature.The key tools in the analysis are estimates of absorbing type with the property of exponentially time‐decreasing contribution of the initial data. Such estimates allow not only to prolong the solution step by step on the infinite time interval but also to conclude the existence of an absorbing set. Copyright © 2009 John Wiley & Sons, Ltd.
Unequivocal assignments of flavonoids from Tephrosia sp. (Fabaceae)
Authors: Arriaga A. M. C. , Lima J. Q. , Vasconcelos J. N. , de Oliveira M. C. F. , Andrade‐Neto M. , Santiago G. M. P. , Uchoa D. E. A. , Malcher G. T. , Mafezoli J. , Braz‐Filho R. 
Published: March 2009

Abstract1H and 13C NMR chemical shifts of praecansone B, pongaflavone and dehydrorotenone isolated from Tephrosia egregia Sandw and obovatin from T. toxicaria Pers. were unambiguously assigned by 1D and 2D NMR experiments including 1H, 1H COSY, gHMQC and gHMBC, allowing the correction of literature assignments.Copyright © 2009 John Wiley & Sons, Ltd.
Guaranteed energy error bounds for the Poisson equation using a flux‐free approach: Solving the local problems in subdomains
Authors: Parés N. , Santos H. , Díez P. 
Published: March 2009

AbstractA method to compute guaranteed upper bounds for the energy norm of the exact error in the finite element solution of the Poisson equation is presented. The bounds are guaranteed for any finite element mesh however coarse it may be, not just in the asymptotic regime. The bounds are constructed by employing a subdomain‐based a posteriori error estimate which yields self‐equilibrated residual loads in stars (patches of elements). The proposed approach is an alternative to standard equilibrated residual methods providing sharper bounds. The use of a flux‐free error estimator improves the effectivities of the upper bounds for the energy while retaining the certainty of the bounds. Copyright © 2009 John Wiley & Sons, Ltd.
Natural fiber hybrid composites—A comparison between compression molding and resin transfer molding
Authors: Idicula Maries , Sreekumar P.A. , Joseph Kuruvilla , Thomas Sabu 
Published: March 2009

AbstractShort randomly oriented intimately mixed banana and sisal hybrid fiber‐reinforced polyester composites having varying volume fraction of fiber were fabricated by compression molding (CM) and resin transfer molding (RTM) techniques by keeping the volume ratio of banana and sisal, 1:1. The static mechanical properties such as tensile, flexural, and impact behavior were studied. The dynamic mechanical properties were also evaluated. Resin transfer molded composites showed enhanced static and dynamic mechanical properties, compared with the compression molded samples. To analyze the fracture surface morphology of the composites, scanning electron microscopy (SEM) was also performed. Water sorption studies revealed that the water uptake of RTM fabricated composites was lower than that of the compression molded composites. The void content of the RTM composites was also found to be lower than that of the other one. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers
Tribological properties of PTFE‐filled thermoplastic polyimide at high load, velocity, and temperature
Authors: Samyn Pieter , Schoukens Gustaaf 
Published: March 2009

AbstractThe effect of 20 wt% polytetrafluoroethylene (PTFE) fillers on the friction and wear properties of thermoplastic polyimides (TP) are investigated, under dry sliding in line contact against steel under 50 to 200 N, 0.3 to 1.2 m/s, and 60 to 260°C. Besides the lubricating mechanisms of PTFE based on mechanical shear, the thermal and tribophysical interactions in the sliding interface are considered in this research by using thermoanalytical measurements, Raman spectroscopy, and calculating the maximum polymer sliding temperatureT*. The effect of hydrolysis of the TP bulk material, causing high friction at 100 to 140°C, is covered by PTFE. A transition atpv‐values 2.2 MPa m/s (T* = 120°C) is due to thermally controlled sliding of PTFE, while a transition atpv‐values 3.2 MPa m/s (T* = 180°C) remains controlled by degradation of the TP bulk material into monomer fractions. The reduced coefficient of friction in the presence of PTFE leads to smaller degradation and orientation of the molecular back‐bone and side‐chains within the TP structure. The formation of a homogeneously mixed transfer film is only observed at 180 to 260°C. The PTFE forms a fibrillar structure during wear at high sliding velocities, while they wear as separate particles at high normal loads. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers
Experimental characterization and numerical simulation of the humidity absorption process in glass reinforced composites under dissymmetric exposure conditions
Authors: Ben Daly H. , Harchay M. , Belhadjsalah H. , Boukhili R. 
Published: March 2009

AbstractThis article investigates the dissymmetrical water absorption process in E‐glass fiber reinforced polyester composites containing fillers and low profile additives. Two different cases of dissymmetrical exposures to water were considered. In the first case, only one side of the aged specimen was exposed to water at different temperatures, the other side was exposed to air. In the second case, both sides were exposed to water, but at different temperatures on each side. The moisture diffusivity and the maximum moisture content reached by the composites were determined using the gravimetric test method. In the first case of the dissymmetrical immersion, the temperature inside the aged specimen was found to be almost constant and the kinetic of the water diffusion was found to obey perfectly the one‐dimensional Fick's second law. In the second case, the specimen temperature varies from one side to the other, thus preventing the use of Fick's laws. Alternatively, the use of the finite element code ABAQUS provided an excellent agreement between the experimental and simulated results in both cases of dissymmetrical immersions, as well as in the case of symmetrical immersion where the two sides were exposed to the same environmental conditions. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers
Effect of fiber orientation on viscoelastic properties of polymer matrix composites subjected to thermal cycles
Authors: Coban Onur , Bora Mustafa Ozgur , Sinmazcelik Tamer , Gunay Volkan 
Published: March 2009

AbstractFibers in polymer composites can be designed in various orientations for their usage in service life. Various fiber orientated polymer composites, which are used in aeroplane and aerospace applications, are frequently subjected to thermal cycles because of the changes in body temperatures at a range of −60 to 150°C during flights. It is an important subject to investigate the visco‐elastic properties of the thermal cycled polymer composite materials which have various fiber orientations during service life. Continuous fiber reinforced composites with a various fiber orientations are subjected to 1,000 thermal cycles between the temperatures of 0 and 100°C. Dynamic mechanic thermal analysis (DMTA) experiments are carried out by TA Q800 type equipment. The changes in glass transition temperature (Tg), storage modulus (E′), loss modulus (E′′) and loss factor (tan δ) are inspected as a function of thermal cycles for different fiber orientations. It was observed that thermal and dynamic mechanical properties of the polymer composites were remarkably changed by thermal cycles. It was also determined that the composites with [45°/−45°]s fiber orientation presented the lowest dynamic mechanical properties. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Experimental investigation on the abrasive wear behavior of nanoclay‐filled EVA/LDPE composites
Authors: Kumar B.N. Ravi , Suresha B. , Sailaja R.R.N. , Venkataramareddy M. 
Published: March 2009

AbstractThe article presents the results of experimental investigation on three‐body abrasive wear behavior of nanoclay‐filled EVA/LDPE (NC‐EVA/LDPE) composites. NC‐EVA/LDPE composites with and without compatibilizer were prepared by Brabender Co‐Twin extruder (Make: CMEI, Model: 16CME, SPL) and poly(ethylene‐co‐glycidyl methacrylate) was used as the compatibilizer. The mechanical properties were evaluated using Universal testing machine. In three‐body wear tests, silica sand particles of size 200–250 μm were used as dry and loose abrasives. Three‐body abrasive wear studies were carried out using dry sand/rubber wheel abrasion test rig. The effect of abrading distance on the abrasive wear behavior of neat EVA, EVA/LDPE, and NC‐EVA/LDPE composites was reported. The results showed that the wear volume loss is increased with increase in abrading distance and the specific wear rate decreased with increase in abrading distance. However, the presence of nanoclay filler in EVA/LDPE composite showed a promising trend. Abrasive wear volume of the composites was correlated with mechanical properties such as hardness, tensile strength, and percentage elongation. However, higher weight percentage of LDPE in EVA increased the wear rate. The results indicate that NC‐EVA/LDPE with compatibilizer composite exhibits good abrasive wear resistance compared with NC‐EVA/LDPE without compatibilizer. Attempts to explain these differing trends are made in this work by analyzing the features observed on the worn surface samples by employing scanning electron microscopy (SEM). POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Influence of alkali‐treated fibers on the mechanical properties and machinability of roselle and sisal fiber hybrid polyester composite
Authors: Athijayamani A. , Thiruchitrambalam M. , Natarajan U. , Pazhanivel B. 
Published: March 2009

AbstractIn this work, the alkali‐treated roselle and sisal fibers were used as reinforcement fillers for thermosetting matrix with aim of obtaining better mechanical properties and machinability of natural fiber hybrid polyester composite. However, their mechanical properties and machinability were compared with untreated fiber composites. The roselle and the sisal fibers were subjected to a 10% sodium hydroxide solution treatment at different duration of 2, 4, 6, and 8 h. Besides, the fractured surfaces of composite specimen were investigated using scanning electron microscopy. Drill hole profiles were analyzed using profile projector and machine vision inspection system. An improvement in strength and stiffness combined with high toughness was achieved by treating the fibers using 10% NaOH solution. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Effect of processing technique on the dispersion of carbon nanotubes within polypropylene carbon nanotube‐composites and its effect on their mechanical properties
Authors: Esawi Amal M.K. , Salem Hanadi G. , Hussein Hanady M. , Ramadan Adham R. 
Published: March 2009

AbstractCarbon nanotube‐reinforced polymer composites are being investigated as promising new materials having enhanced physical and mechanical properties. With regards to mechanical behavior, the enhancements reported thus far by researchers are lower than the theoretical predictions. One of the key requirements to attaining enhanced behavior is a uniform dispersion of the nanotubes within the polymer matrix. Although solvent mixing has been used extensively, there are concerns that any remaining solvent within the composite may degrade its mechanical properties. In this work, a comparison is carried out between solvent and “solvent‐free” dry mixing for dispersing multiwall carbon nanotubes in polypropylene before further melt mixing by extrusion. Various weight fractions of carbon nanotubes (CNTs) are added to the polymer and their effect on the mechanical properties of the resulting composites is investigated. Enhancements in yield strength, hardness, and Young's modulus when compared with the neat polymer, processed under similar conditions, are observed. Differences in mechanical properties and strain as a function of the processing technique (solvent or dry) are also clearly noted. In addition, different trends of enhancement of mechanical properties for the solvent and dry‐mixed extrudates are observed. Dry mixing produces composites with the highest yield strength, hardness, and modulus at 0.5 wt% CNT, whereas solvent mixing produces the highest mechanical properties at CNT contents of 1 wt%. It is believed that this difference is primarily dependent on the dispersion of CNTs within the polymer matrix which is influenced by the processing technique. Field emission scanning electron microscopy analysis shows the presence of clusters in large wt% CNT samples produced by dry mixing. Samples produced by solvent mixing are found to contain homogeneously distributed CNTs at all CNT wt fractions. CNT pull‐out is observed and may explain the limited enhancement in mechanical properties. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers
Electropolymerization of poly(methyl pyrrole)/carbon nanotubes composites derived from ionic liquid
Authors: Ahmad Shahzada 
Published: March 2009

AbstractThe use of conjugated polymer in electronics devices is believed to be the driving force for the tremendous R & D activity involving these materials. In this study, electropolymerization of N‐methyl pyrrole/carbon nanotubes composites has been performed galvanostatically in ionic liquid medium. A well‐ordered polymer composites of poly(methylpyrrole)/carbon nanotubes (pMPy/CNTs) nanostructures has been observed as revealed by atomic force microscopy. The current vs. voltage curves demonstrates an ohmic nature of the synthesized polymers. pMPy/CNT films are found more conductive than the pMPy films. It is believed that, this route can be further fined to other organic conjugated systems and, thus, opens an avenue for application for a host of polymers in electronic devices. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Study of pseudo‐multilayer structures based on starch‐polycaprolactone extruded blends
Authors: Bélard Laurent , Dole Patrice , Avérous Luc 
Published: March 2009

AbstractThis article is focused on the analysis of the structure‐process relationships of biodegradable materials. It is mainly focused on the analysis of phase separation phenomenon occurring during the extrusion of plasticized starch/polycaprolactone blends, in a slit die. Rheological characterizations are carried out, in‐line in an instrumented slit die at the exit of the extruder and, out‐line with different rheometers. In certain conditions, a pseudo‐multilayer structure can be generated with a polyester rich skin. Then, Electron Spectroscopy for Chemical Analysis (ESCA) and Fourier Transformed Infrared Attenuated Total Reflectance (FTIR‐ATR) analyses are conducted to evaluate semi‐quantitatively the polyester surface enrichment. In the range of available shear rates, the phase separation is mainly driven by the molecular weight of polycaprolactone, linked to its molten state viscosity. Three zones of surface enrichment, dependent on the molecular weights, are identified. Above 60,000 g·mol−1, no surface enrichment could be detected; below 37,000 g·mol−1, the phase separation occurs with no dependence on the processing conditions; between these two limits, the phase separation depends on both, the formulation and the processing conditions. A correlation between the rheological measurements and the phase separation is given. A predictive criterion based on the viscous behavior of the blend is established. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Synthesis and characterization of styrene butadiene rubber—Bentonite clay nanocomposites
Authors: Chakraborty Sugata , Sengupta Rajatendu , Dasgupta Saikat , Mukhopadhyay Rabindra , Bandyopadhyay Samar , Joshi Mangala , Ameta Suresh C. 
Published: March 2009

AbstractIn the present study, naturally occurring unfractionated bentonite clay was used to prepare styrene butadiene rubber/bentonite clay nanocomposite by latex stage blending. The bentonite clay was organo‐modified by in situ resol formation by the reaction of resorcinol and formaldehyde. The latex clay mixture was co‐coagulated with acid. The resulting clay masterbatch was compounded and evaluated by Fourier Transform Infrared spectroscopy, X‐ray diffraction (XRD), Transmission Electron Microscopy (TEM), Energy Dispersive X‐ray spectroscopy (EDS), Scanning Electron Microscopy, Thermogravimetric analysis, and Differential Scanning Calorimetry. XRD showed that the interplanar distance of the in situ resol‐modified bentonite clay increased from 1.23 to 1.41 nm for the unmodified bentonite. TEM analysis indicated partial exfoliation and/or intercalation. EDS (Si and Al mapping) of the clay revealed the nature of the dispersion in the nanocomposites vis‐à‐vis the conventional styrene‐butadiene rubber (SBR)/bentonite clay composite. Thermogravimetric analysis was used to compare the decomposition trends of the SBR/clay nanocomposites with the SBR/clay composite. The glass transition temperature of SBR/clay nanocomposites increased as compared with that of neat SBR. Substantial improvement in most of the other mechanical properties was also observed in case of the nanocomposites. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Anisotropic mechanical properties of hot‐pressed PVDF membranes with higher fiber alignments via electrospinning
Authors: Na Haining , Li Qunying , Sun Hua , Zhao Ci , Yuan Xiaoyan 
Published: March 2009

AbstractBy the use of a high‐speed collection drum, poly(vinylidene fluoride) (PVDF) was electrospun into aligned ultrafine fibrous membranes from its solutions in a mixture of N,N‐dimethylformamide and acetone (9:1, v/v), and a continuous hot‐press post‐treatment was performed on the membranes to improve their mechanical properties. Anisotropic tensile results and rupture behaviors of the hot‐pressed PVDF membranes with higher fiber alignments in both revolving direction (RD) and cross direction were obtained. It was found that, due to the true fracture of electrospun fibers and improvement of the interfiber compaction by hot‐press, the tensile strength and modulus of the hot‐pressed membranes in RD reached the highest values at 58.12 ± 4.46 MPa and 519.9 ± 34.1 MPa, respectively when the collection speed was 10.42 m/s. The decrease of porosity and liquid absorption also represented the compaction improvement of the electrospun fibrous membranes. The combination of fiber alignments and hot‐press could provide a novel method to fabricate high strength of electrospun membranes which have highly potential applications in filtration or battery separators. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers