bluuebunny/crossref_metadata_2025 huggingface dataset:
On widening the angular existence domain for Dyakonov surface waves using the Pockels effect
Authors: Nelatury Sudarshan R. , Polo John A. , Lakhtakia Akhlesh
Published: June 2008

The propagation of Dyakonov surface waves (DSWs) at the planar interface between an isotropic material and a linear electro‐optic birefringent material can be dynamically controlled using the Pockels effect. The range of directions for DSW propagation has been previously found to be rather narrow. By careful choice of various parameters, this range of directions can be increased by more than an order of magnitude. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2360–2362, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23698
A fuzzy logic based device for the determination of temperature dependence of EDFAs
Authors: Goktas H. Haldun , Yucel Murat
Published: June 2008

In this study, a fuzzy logic (FL)‐based device is designed, constructed, and applied to a C band (1530–1565 nm) erbium‐doped fiber amplifier to obtain maximum signal gain and appropriate erbium‐doped fiber length for the temperature range between −20 and +60°C. The fuzzy rules—which are embedded into the circuit—are compiled using the input variables which are, namely, the signal wavelength and the temperature, whereas the output parameters are the signal gain and the appropriate fiber length providing the maximum signal gain. The FL‐based device provides the predictions for the fiber length providing the maximum signal gain against the input signal wavelength, and the temperatures within the accuracy level of 95–99%. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2331–2334, 2008; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.23699
Highly efficient class‐F GaN HEMT Doherty amplifier for WCDMA applications
Authors: Lee Yong‐Sub , Lee Mun‐Woo , Jeong Yoon‐Ha
Published: June 2008

This article presents a high‐efficiency GaN HEMT class‐F Doherty amplifier for 2.14‐GHz WCDMA applications. From the measured results, the proposed amplifier shows the PAE and drain efficiency of 56.3 and 60.1% at 39.5 dBm (6‐dB back‐off power from Psat) for a single tone. For a one‐carrier WCDMA signal, the CFDA shows the PAE of 44.9% with an ACLR of −22.1 dBc (±2.5 MHz offset) at 36.5 dBm, while an ACLR of −35.4 dBc with the PAE of 39.7% is achieved for the CEDA after linearity optimization. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2328–2331, 2008; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.23700
Broadband parallel‐coupled quadrature coupler with floating‐potential ground plane conductor
Authors: Abbosh A. M.
Published: June 2008

The design of a parallel‐coupled directional coupler, which has a broadband performance, is presented. A floating‐potential ground plane conductor is used underneath the coupled region to relax the requirement for a narrow slot between the coupled lines and to improve the isolation and return loss performance of the device. The simulated and measured results show that the designed coupler exhibits a coupling of 3 ± 1 dB across the band 4–10.2 GHz, when the spacing between the coupled lines is 0.13 mm, which is easy to manufacture. This broadband coupling is accompanied by an isolation and return loss which are better than 15 dB across the band 3.1–10.6 GHz. The simulated and measured results show good phase stability and flat group delay across the ultra wideband. The designed device has a compact size with a dimension of 30 mm × 20 mm. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2304–2307, 2008; Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.23701
Regulatory changes of apoptotic factors in the bovine corpus luteum after induced luteolysis
Authors: Kliem H. , Berisha B. , Meyer H.H.D. , Schams D.
Published: June 2008

The corpus luteum (CL) offers the opportunity to study not only proliferative, but also regressive processes. During luteolysis of the CL a sudden death of luteal and endothelial cells seems to be involved (apoptosis). The aim of this study was to examen the mRNA expression of factors known to be involved in apoptotic processes: monocyte chemoattractant protein‐1 (MCP‐1), factors of the extrinsic and intrinsic apoptotic pathways, caspase3, ‐6, ‐7 and interferone gamma (IFNγ). Luteolysis was induced by injection of 500 µg Cloprostenol during mid‐luteal phase. The CLs were collected at 0.5, 2, 4, 12, 24, 48, and 64 hr after PGF2α‐injection. Control CLs (Days 8–12) were collected at the slaugtherhouse. Real‐time RT‐PCR determined the mRNA expressions. Western blot analysis of poly(ADP‐ribose) polymerase (PARP‐1) and IFNγ as well as protein measurement of tumor necrosis factor α (TNFα) by EIA were performed. The mRNA levels of MCP‐1, IFNγ and most factors of the extrinsic pathway were significantly increased between 0.5 and 2 hr. The factors of the intrinsic pathway were mostly later up‐regulated at 24–48 hr after PGF2α. Caspase6 and 3 revealed a significant increase from 2 and 12 hr, respectively, whereas caspase7 was significantly up‐regulated after 24 hr. The protein level of TNFα increased significantly to a maximum level at 12 hr. The Western blot revealed an increasing level of an 89 kDa fragment of PARP‐1 from 12 to 24 hr, which is specific for apoptosis. We assume that the extrinsic pathway is more important for the onset of luteolysis, because of its earlier and higher increase during induced luteolysis. Mol. Reprod. Dev. 76: 220–230, 2009. © 2008 Wiley‐Liss, Inc.
Neurophysiology in neurourology
Authors: Roberts Margaret M.
Published: June 2008

The bladder has only two essential functions. It stores and periodically empties liquid waste. Yet it is unique as a visceral organ, allowing integrated volitional and autonomous control of continence and voiding. Normal function tests the integrity of the nervous system at all levels, extending from the neuroepithelium of the bladder wall to the frontal cortex of the brain. Thus, dysfunction is common with impairment of either the central or peripheral nervous system. This monograph presents an overview of the neural control of the bladder as it is currently understood. A description of pertinent peripheral anatomy and neuroanatomy is provided, followed by an explanation of common neurophysiological tests of the lower urinary tract and associated structures, including both urodynamic and electrodiagnostic approaches. Clinical applications are included to illustrate the impact of nervous system dysfunction on the bladder and to provide indications for testing. © 2008 Wiley Periodicals, Inc. Muscle Nerve 38: 815–836, 2008
Therapeutic stimulation of denervated muscles: The influence of pattern
Authors: Ashley Zoe , Sutherland Hazel , Russold Michael F. , Lanmüller Hermann , Mayr Winfried , Jarvis Jonathan C. , Salmons Stanley
Published: June 2008

Muscular atrophy due to denervation can be substantially reversed by direct electrical stimulation. Some muscle properties are, however, resistant to change. Using a rabbit model of established denervation atrophy, we investigated whether the extent of restoration would vary with the stimulation protocol. Five patterns, delivering 24,000–480,000 impulses/day, were applied for 6 or 10 weeks. The wet weight, cross‐sectional area, tetanic tension, shortening velocity, and power of denervated muscles subjected to stimulation all increased significantly. The fibers were larger and more closely packed and there was no evidence of necrosis. There was a small increase in excitability. Isometric twitch kinetics remained slow and fatigue resistance did not improve. The actual pattern of stimulation had no influence on any of these findings. The results, interpreted in the context of ultrastructural changes and an ongoing clinical study, reaffirm the clinical value of introducing stimulation during the initial non‐degenerative phase. They indicate that there would be little therapeutic benefit in adopting regimes more energetically demanding than those in current use, and that the focus should now shift to protocols that represent the least intrusion into activities of daily living. © 2008 Wiley Periodicals, Inc. Muscle Nerve 38: 875–886, 2008
Myotonic dystrophy type 1 coexisting with myasthenia gravis and thymoma
Authors: Feyma Timothy , Carter Gregory T. , Weiss Michael D.
Published: June 2008

Myotonic dystrophy type 1 (DM1) is an autosomal‐dominant multisystemic disorder that may rarely be associated with benign and malignant neoplasms. Cases of both thymoma and myasthenia gravis in association with DM1 are extremely rare. A literature review revealed only three prior reports. We present a 51‐year‐old man with a family history of DM1 and fluctuating diplopia and ptosis, who was found to have acetylcholine receptor–binding antibodies, thymoma, and a clinical presentation compatible with ocular myasthenia gravis as well as positive genetic testing for DM1. Needle electromyographic (EMG) study demonstrated diffuse runs of myotonic discharges in multiple muscles, consistent with the diagnosis of DM1. Single‐fiber EMG showed both increased jitter and blocking. Due to somatic instability, which has been shown previously in DM1, the myotonin protein kinase (DMPK) gene appears to act as a tumor suppressor. Therefore, abnormal CTG repeat expansions in the gene could lead to the development of thymoma and myasthenia gravis. Muscle Nerve 38: 916–920, 2008
Calibrated quantitative ultrasound imaging of skeletal muscle using backscatter analysis
Authors: Zaidman Craig M. , Holland Mark R. , Anderson Christian C. , Pestronk Alan
Published: June 2008

We evaluated the ability of an ultrasound method, which can characterize cardiac muscle pathology and has reliability across different imaging systems, to obtain calibrated quantitative estimates of backscatter of skeletal muscle. Our procedure utilized a tissue‐mimicking phantom to establish a linear relationship between ultrasound grayscale and backscatter levels. We studied skeletal muscles of 82 adults: 45 controls and 37 patients with hereditary myopathies. We found that skeletal muscle ultrasound backscatter levels varied with probe orientation, age, and muscle contraction and pathology. Reliability was greater with the probe in longitudinal compared with transverse planes. Backscatter levels were higher in those >40 years of age, in muscle extension than flexion, and in myopathic patients than controls. Calibrated measurements of muscle backscatter have sensitivity and specificity in identifying and reliably measuring levels of skeletal muscle pathology. Muscle Nerve 38: 893–898, 2008
Intranervous immunoglobulin deposits: An underestimated mechanism of neuropathy
Authors: Vallat Jean‐Michel , Magy Laurent , Richard Laurence , Piaser Martine , Sindou Philippe , Calvo Judith , Ghorab Karima , Cros Didier
Published: June 2008

There are several pathogenic mechanisms of peripheral nerve involvement in patients with monoclonal dysglobulinemia. Intranervous proliferation of malignant cells, immunoglobulin, or amyloid deposits in the endoneurial space can only be determined by examination of nerve biopsy specimens. We present clinical, electrophysiological, and histological data from seven patients whose polyneuropathy was induced by immunoglobulin deposits in the endoneurial space. As these lesions cannot be demonstrated on clinical and electrophysiological grounds, the indication for nerve biopsy derives from careful analysis of each patient presenting with a polyneuropathy and a monoclonal dysglobulinemia. To visualize and clearly characterize these deposits, electron microscopic examination is indispensable. Immunocytochemical methods using both light and electron microscopy for ultrastructural analysis are of great value. Demonstration of endoneurial immunoglobulin deposits may have major therapeutic consequences. Indeed, identification of these deposits prompted the use of aggressive treatment, which was quite effective in five of our seven patients. Muscle Nerve 38: 904–911, 2008
Axonal neuropathy due to myelin protein zero mutation misdiagnosed as amyloid neuropathy
Authors: Briani Chiara , Adami Fausto , Cavallaro Tiziana , Taioli Federica , Ferrari Sergio , Fabrizi Gianmaria
Published: June 2008

In up to 50% of chronic idiopathic axonal neuropathies, an underlying diagnosis may be identified, including hereditary neuropathy. Charcot–Marie–Tooth disease (CMT) is clinically and genetically heterogeneous. Several mutations in the myelin protein zero (MPZ) gene have been associated with different CMT phenotypes, including classical demyelinating CMT1B and the axonal form of the disease. Primary amyloidosis, a rare disease where the amyloid is formed by the N‐terminal portion of a monoclonal immunoglobulin light chain, may be complicated by polyneuropathy. We report a patient who was incorrectly diagnosed with amyloid neuropathy, but was found to have axonal CMT1B only after sural nerve biopsy ruled out an acquired amyloid neuropathy. Muscle Nerve 38: 921–923, 2008
IBLU decompositions based on Padé approximants
Authors: Buzdin A. , Logashenko D. , Wittum G.
Published: June 2008

In this paper, we introduce a new class of frequency‐filtering IBLU decompositions that use continued‐fraction approximation for the diagonal blocks. This technique allows us to construct efficient frequency‐filtering preconditioners for discretizations of elliptic partial differential equations on domains with non‐trivial geometries. We prove theoretically for a class of model problems that the application of the proposed preconditioners leads to a convergence rate of up to 1−O(h1/4) of the CG iteration. Copyright © 2008 John Wiley & Sons, Ltd.
Using the complex polynomial method with Mathematica to model problems involving the Laplace and Poisson equations
Authors: Poler A.C. , Bohannon A.W. , Schowalter S.J. , Hromadka T.V.
Published: June 2008

The complex polynomial method variant of the well‐known complex variable boundary element method (CVBEM) is reexamined in its utility in solving Partial Differential Equations (PDE) of the Poisson and Laplace type. Because the CVBEM was recently extended to three and higher dimensions, the use of complex polynomials to solve higher dimension PDE becomes apparent and therefore the advantages afforded by the use of complex polynomials can be brought to focus on higher dimension problems. Because complex polynomials involve use of computational algorithms that require high accuracy in numerical precision, including the solution of fully populated nonsymmetric matrices, the computer program Mathematica is evaluated for use as the underlying computational engine. Furthermore, Mathematica is evaluated for its internal high‐accuracy computational features and algorithms, including ease of program setup. In this research, the new program is found to provide at least a 5‐fold increase in complex polynomial degree utilization (from degree 10 to degree 50), with computational speed less than was involved in the original degree 10 approximation of Hromadka and Guymon [ASCE J Hydraulic Eng 110 (1984), 329–339], and with exceptional computational accuracy and reporting features. The Mathematica program is quite small and is provided to the reader as freeware and can be obtained from the first author. © 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009
Chebyshev‐Legendre spectral method for solving the two‐dimensional vorticity equations with homogeneous Dirichlet conditions
Authors: Wu Hua , Ma Heping , Li Huiyuan
Published: June 2008

The Chebyshev‐Legendre spectral method for the two‐dimensional vorticity equations is considered. The Legendre Galerkin Chebyshev collocation method is used with the Chebyshev‐Gauss collocation points. The numerical analysis results under the L2‐norm for the Chebyshev‐Legendre method of one‐dimensional case are generalized into that of the two‐dimensional case. The stability and optimal order convergence of the method are proved. Numerical results are given. © 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009
Effect of the various coupling agents on the mechanical and physical properties of thermoplastic‐bagasse fiber composites
Authors: Youssef H.A. , Ismail M.R. , Ali M.A.M. , Zahran A.H.
Published: June 2008

Various types of bonding agents have been tried with blends of bagasse fibers and some thermoplastics such as low‐density polyethylene (LDPE), high‐density polyethylene (HDPE), polystyrene (PS), polypropylene (PP), and polyvinyl chloride (PVC). These bonding agents are, namely, pentaerythritol tetracrylate (PETA), 1,6 hexandiol diacrylate (HDA), and dicumyl peroxide (DCP). In addition, a traditional coupling agents 3‐aminopropyltrimethoxy silane (AMPS) and di‐aminopropyltrimetoxy silane (DAMPS) were included for comparison. Electron beam (EB) irradiation is applied only for LDPE and HDPE at 40 and 10 kGy, respectively, before mixing with bagasse fibers. The data obtained reveal that incorporation of bonding agents remarkably increases the mechanical properties for all samples under investigation; the maximum improvement is observed in LDPE followed by HDPE, PP, PS, and PVC composites. Also, the physical properties enhanced but not at the same degree as mechanical properties. Among the tested bonding agents, it was found that PETA, DCP followed by DAMPS have highest efficiency in LDPE, whereas in case of HDPE, EB radiation was higher than PETA followed by DCP. PETA was superior in case of PS composites. Furthermore, PETA and HDA experienced higher efficiency than DAMPS and AMPS in case of PP and PVC composites. Comparison between the properties of thermoplastic composites and medium density fiberboard (MDF) reveals that most of the properties of thermoplastics composites are better than MDF. However, modulus of rupture of MDF was found to be slightly higher than thermoplastics except for PVC composite. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers
Finite element analysis for thermoforming process of continuous fiber reinforced thermoplastic composites
Authors: Abadi Mohammad Tahaye
Published: June 2008

An implicit finite element method is presented to model thermoforming process of thermoplastic materials reinforced with unidirectional fibers or woven fabric. The composite materials are regarded as a homogenized anisotropic viscous fluid restricted by kinematical constrains of material incompressibility and fiber inextensibility at the forming temperature. Unlike previous numerical approaches considering quasi‐static assumptions during each increment, a high order polynomial expression is used to define continuous displacement and velocity fields. The material parameters are also updated during each increment to determine the displacement and velocity fields satisfying the equilibrium equations as well as the kinematical constrains both in the rate and total deformation forms. An iterative solution method is presented to solve the finite element formulation. The numerical results are compared with analytical solutions and the results of previous implicit finite element approaches to demonstrate the computational accuracy and efficiency of the present method. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Effect of frequency upon fatigue strength of a short glass fiber reinforced polyamide 6: A superposition method based on cyclic creep parameters
Authors: Bernasconi Andrea , Kulin Robb M.
Published: June 2008

The fatigue behavior of a conditioned short glass‐fiber reinforced polyamide 6 was studied and the effect of the cyclic frequency investigated. Load controlled fatigue tests were performed, and the strains and surface temperature of specimens were recorded continuously. The number of cycles to failure was found to be dependent upon cyclic creep rate, as is typical for short glass fiber reinforced polyamides in the conditioned state. A strong reduction of fatigue strength was observed for increasing cyclic load frequency. This was mainly related to the specimen temperature increase due to hysteretic self heating and its effect on the cyclic creep speed. A frequency superposition method is proposed, expressing the relationship between temperature rise, applied stress, and cyclic creep speed in terms of a parameter derived from the Larson–Miller steady creep parameter. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
SiC dispersed polysulphide epoxy resin based functionally graded material
Authors: Hashmi S.A.R. , Dwivedi U.K.
Published: June 2008

Gravity and centrifugal castings are considered the most economical and attractive processes for making functionally graded materials (FGMs). The control on property change in radial direction in aforesaid methods is mainly based on the initial concentration, viscosity, time, centrifugal force, particle size, and density difference in dispersed and dispersion medium as per Stoke's law. The modified Stoke's law in the form of HD model that takes into account the intrinsic changes in viscosity those occur during the polymerization of resins, was used for determining changes in concentration with time at different locations of test samples for SiC dispersed poly sulphide epoxy resin FGM. The experiments as well as simulation were conducted under gravity as well as centrifugal force. The simulated results are in good agreement with those ofexperiments. The process parameters, initial concentration, etc., can be selected for a desired concentration profile of FGM. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Study on microstructure, rheological, and mechanical properties of cellulose short fiber reinforced TPVs based on EPDM/PP
Authors: Goharpey F. , Mirzadeh A. , Sheikh A. , Nazockdast H. , Katbab A.A.
Published: June 2008

The morphology, rheology, and mechanical properties of the dynamically vulcanized thermoplastic elastomer based on EPDM/PP (60/40, w:w) containing 5, 10, and 20% of cellulose short fiber were studied. From the results it was found that addition of 5% of cellulose fiber has no significant effect on the maximum torque associated with the dynamic vulcanization stage, while higher concentration of fibers decreased the maximum torque. These results were explained in terms of influence of cellulose fibers on the extent of agglomeration formed between the cured rubber particles. The results of tensile test performed on the samples showed that incorporation of 5% of cellulose fibers into the sample has an increasing effect on elongation at break with no appreciable change in tensile behavior. However increasing the cellulose fibers content of the sample to 20% had a remarkable change in tensile properties of the sample resulting in a toughened plastic type behavior. The melt elasticity of the sample containing 5% of cellulose fibers particularly at low shear rate range was found to be lower than that of the sample without fibers indicating the role of fibers in weakening of cured rubber particle agglomeration. This was supported with the results of the relaxation time distribution H(λ) and scanning electron microscopy of the samples. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Preparation and characterization of nylon 6/organoclay nanocomposite filament fibers
Authors: Kim Kap Jin , Lee Jong Soon , Prabu Arun Anand , Kim Taek Hyun
Published: June 2008

A series of nylon 6 (NY6)/organoclay nanocomposites were prepared via in situ polymerization of ε‐caprolactam in the presence of 1,2‐aminododecanoic acid‐intercalated montmorillonite (ADA‐MMT) organoclay (1–5 wt%) using 6‐aminocaproic acid as polymerization catalyst. The extent of organoclay dispersion in NY6 matrix was analyzed using WAXD and SEM measurements. DSC studies revealed marginal shift in melting and melt‐crystallization peaks toward lower temperature with increasing clay content. Melt viscosity studies for NY6/ADA‐MMT exhibited higher shear‐thinning behavior than neat NY6 probably due to the slip between NY6 matrix and exfoliated organoclay platelets during shear flow. The prepared nanocomposites were melt‐spun and studied for their property improvements against varying clay content, draw ratios, and annealing conditions. Birefringence and sonic velocity values increased initially at lower draw ratios (≤2.5) due to increased orientation of molecular chains along the drawing direction but saturated at higher draw ratio (3.0) for all the samples. At the same draw ratio; compared to neat NY6, NY6/organoclay fibers showed increased chain orientation along the drawing direction which can be attributed to the “tethering effect” of organoclay on NY6 matrix. The initial modulus and stress at break were sensitive to factors such as draw ratio, clay content, and annealing conditions. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Interfacial adhesion and molecular diffusion in melt lamination of wood sawdust/ebonite NR and EPDM
Authors: Yamsaengsung W. , Sombatsompop N.
Published: June 2008

Adhesion mechanisms and peel strengths of wood/ebonite NR‐EPDM laminates were investigated. Three different chemical coupling agents: namely; N‐(β aminoethyl)‐γ‐aminopropyl‐triethoxysilane (AAS), 3‐methacryloxypropyl trimethoxysilane (ACS), and Bis‐(3‐triethoxylpropyl) tetrasulfan (Si69) were introduced into the wood/NR composites to enhance an interaction between wood sawdust (SD) particles and NR molecules, and to improve the adhesion strength between the SD/NR and EPDM layers. The quantitative evidences were given to explain the changes in the adhesion or peel strengths of the SD/NR‐EPDM laminates through scanning electron microscopy with energy dispersive X‐ray analysis (SEM‐EDS). The experimental results indicated that the suitable cure time and cure temperature for SD/NR‐EPDM melt‐laminates were the tc90 of SD/NR composites and 140°C, respectively. The Si69 coupling agent was found to be the most effective coupling agent as compared with AAS and ACS coupling agents. The Si69 of 0.5 wt% was recommended for the optimizations of the tensile modulus of the SD/NR composites and the peel strength of the SD/NR‐EPDM laminates. The diffusion level between the SD/NR and EPDM layers could be quantitatively substantiated by determining the sulfur content transfer from the SD/NR layer to the EPDM layer. The diffusion and entanglement of molecular chains from the SD/NR to the EPDM layer initiated the co‐crosslinking reaction which played an important role on the changes in the interfacial strength in the SD/NR‐EPDM melt‐laminates. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Rheology and flow behavior of suspensions of nanosized plate‐like particles in polyester resins at the startup of shear flows; Experimental and modeling
Authors: Rajabian Mahmoud , Beheshty Mohammad H.
Published: June 2008

Applications of organoclays to polymer resins are potentially of great technical interest. This research targets preparation and characterization of nanocomposites of organoclays in an unsaturated polyester resin (UP). The nanocomposites with two distinct dispersion levels were compounded in a complex multisteps mixing process at three concentrations and subsequently their microstructures were characterized by XRD. The solution‐state rheological properties of layered silicate/UP were measured in the start‐up of steady state in the simple shear mode and analyzed based on our observations of internal structure of nanoparticles dispersion. Strong shear thinning behavior caused by increasing particle alignment induced by the shear field was observed for the suspensions. Effects of nanoparticles loadings and shearing on transient viscosity of the UP resin were examined. The experimental results show that increasing shear time in nanosuspension preparation steps and hence improvements of nanoplate dispersion in the polyester resin give rise to viscosity of the suspensions. A theoretical analysis of the motion of rigid ellipsoidal particles in a Newtonian fluid based on the thermodynamic approach and Jeffery's analysis of the motion of ellipsoid particles with an interaction term was developed to determine the orientation state of disc‐shape layers and then, the expression for the extra stress tensor was calculated to predict transient viscosity and normal stress differences. It is found that the thin oblate particles have significant orientation preference in the shearing direction. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Curing behavior and properties of epoxy nanocomposites with amine functionalized multiwall carbon nanotubes
Authors: Choi Woo Jin , Powell Robert L. , Kim Dae Su
Published: June 2008

Carbon nanotubes (CNTs) with reactive functional groups such as amines would affect not only properties but also curing behavior of an epoxy nanocomposite system comprising them. Therefore, in this study, an amine functionalization of multiwall CNTs (MWNTs) was carried out via treating pristine MWNTs (PMWNT) with 4‐aminobenzoic acid in polyphosphoric acid. The functionalization was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). Epoxy nanocomposites comprising the PMWNT or functionalized MWNTs (FMWNT) were prepared and their curing behavior and properties were investigated. Differential scanning calorimetry (DSC) was used to obtain experimental conversion data for curing kinetic analysis. The FMWNT accelerated the curing rate of the nanocomposite system. The functionalization induced strong interfacial bonding between the epoxy matrix and the MWNTs, and resulted in considerable improvements in the properties of the nanocomposites. The SEM image showed strong interfacial bonding between the epoxy matrix and the FMWNT. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Investigation on the dynamic melt rheological properties of polypropylene/wood flour composites
Authors: Azizi H. , Ghasemi I.
Published: June 2008

The rheological behavior of polypropylene/wood flour (WF) composite was investigated at constant temperature over a wide range of frequencies using a mechanical compact rheometer operated in the dynamic mode. The effect of WF content, particle size, and coupling agent on melt rheological properties were investigated. The melt rheological data in terms of complex viscosity (η*), storage modulus (G′), loss modulus (G″), and loss tangent (tan δ) were studied and compared for different samples. It was found that complex viscosity increases with increasing wood content and coupling agent. Compatibilization using coupling agent increased both storage modulus and loss modulus, but the variation of storage modulus is more. By increasing wood content storage modulus increases. Complex viscosity, storage modulus, and loss modulus showed a minimum value by increasing of wood particle size. Tan δ decreases with increasing of wood content. Cole–Cole plot indicated that relaxation process changes with addition WF, coupling agent, and using different mesh size of wood. The Han plots revealed the sensitivity of rheological properties with composition at constant temperature. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Bond performance of FRP rebars with various surface deformations in reinforced concrete
Authors: Esfandeh Masoud , Sabet Ali R. , Rezadoust Amir M. , Alavi Mohammad B.
Published: June 2008

One of the methods used to overcome the corrosion problem associated with steel rebars in reinforced concrete is the application of reinforced polymer (FRP) rebars. Bonding between the rebar and concrete is one of the major factors affecting the mechanical behavior of the structures. In this study, FRP rebars with four different surface configurations and geometries were constructed and their bonding to concrete was examined. These include a pultruded rod with a smooth surface (RO), externally wound FRP rib on the pultruded rod (RT), pultruded rod with sand sprayed on the surface (RS), and a combination of the last two configurations (RTS). Bonding strength of the rebars to concrete was assessed using pull‐out test at the embedment lengths of 12 and 18 cm. Results showed that the increase in surface roughness of the rebars and hence a greater inter‐mechanical locking, plays a major role in their bonding strength to concrete. RO rebar showed the lowest bonding strength to the concrete followed by the RT rebar. Bonding strength to concrete in the latter type was entirely controlled by the adhesion strength of the externally wound FRP rib to the pultruded core. RTS rebars with embedment length of 12 cm showed greater adhesion to the concrete, where as, in samples with embedment length of 18 cm, RTS and RS rebars showed close results. In all the tests conducted, delaminating of the surface texture was the major failure mode. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Mechanical and thermal properties of the hybrid composites of vinylester resin and methacryl‐substituted polysilsesquioxane
Authors: Takahashi Tsutomu , Katoh Takeshi , Sakuma Takenori , Someya Yoshihiro , Shibata Mitsuhiro
Published: June 2008

Vinylester resin (VER) composed of bisphenol‐A‐based epoxy methacrylate and styrene was cured finally at 120°C with methacryl‐substituted polysilsesquioxane (ME‐PSQ) prepared from 3‐(trimethoxysilyl)propyl methacrylate and tetramethylammonium hydroxide. The dynamic mechanical and thermal properties of the VER/ME‐PSQ 90/10–60/40 hybrid composites were investigated when compared with crosslinked‐VER (C‐VER) and VER/phenyl‐substituted polysilsesquioxane (Ph‐PSQ) 80/20 composite cured at the same condition. As a result, the VER/ME‐PSQ hybrid composites showed much higher storage modulus (E′) at rubbery state than C‐VER and the VER/Ph‐PSQ composite. The E′ of the hybrid composites increased with increasing ME‐PSQ content. Also, coefficient of thermal expansion of the hybrid composites decreased with increasing ME‐PSQ content. The glass transition temperatures and 5% weight loss temperatures of the VER/ME‐PSQ hybrid composites were almost the same as those of C‐VER and the VER/Ph‐PSQ composite. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Theoretical and experimental determination of tensile properties of nanosized and micron‐sized CaCO3/PA66 composites
Authors: Sisakht Mohsen Rastgoo , Saied Nouri Khorasani , Ali Zadhoush , Hosein Enayati Mohammad , Hasan Pezeshki
Published: June 2008

The objective of this research was to investigate the probability of reinforcing Polyamide66 (PA66) with both micron‐sized and nanosized calcium carbonate (CaCO3) particles. For this purpose, micron‐sized and nanosized CaCO3 particles were used as fillers to prepare microcomposites (conventional composites) and nanocomposites via a polymer solution method. The microcomposites and nanocomposites were found to have higher modulus and lower strength than neat PA66. Also, nanocomposites had higher modulus and strength than microcomposites. Theoretical prediction of elastic modulus was carried out using Rule of mixtures, Guth, Nicolais–Narkis, Hashin–Shtrikman, and Halpin–Tsai equations. Calculated results show that these equations cannot predict the results accurately for the work carried out. However, these models can be used with confidence for the prediction of elastic modulus as experimental data are higher than the calculated values. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Optical study of poly(3‐decylthiophene)/CdS nanocomposites
Authors: Dong Yanmao , Lu Jianmei , Yan Feng , Xu Qingfeng
Published: June 2008

Nanocomposites comprised of poly(3‐alkyl thiophenes) (P3ATs)/semiconductor nanoparticles exhibited excellent photoelectricity performance because of contributions from both the P3ATs and the semiconductor nanoparticles. In this article, poly(3‐decylthiophene) (P3DT) was synthesized and P3DT/CdS nanocomposites were prepared using an in‐situ method. The CdS nanoparticles exhibited strong quantum effect on the photoluminescence (PL) properties of P3DT/CdS and the nanocomposites exhibit an enhanced PL and red‐shifted emission with increasing CdS content. The PL quenched at CdS‐to‐3DT ratio at 0.35 mol%. The charge‐transfer process between P3DT and CdS particles is discussed. P3DT/CdS composites also exhibit excellent nonlinear optical (NLO) properties. The third‐order NLO coefficient of P3DT/CdS (χ(3) = −4.62 × 10−12 esu) is higher than that of P3DT. The P3DT/CdS nanocomposites have potential optical applications. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Thermal properties of PMMA/TiO2 nanocomposites prepared by in‐situ bulk polymerization
Authors: Džunuzović E. , Marinović‐Cincović M. , Vuković J. , Jeremić K. , Nedeljković J.M.
Published: June 2008

The surface of anatase TiO2 nanoparticles, obtained by the controlled hydrolysis of titanium tetrachloride, was modified by 6‐palmitate ascorbic acid. The surface modified TiO2 nanoparticles were dispersed in methyl methacrylate and mixed with a appropriate amount of poly(methyl methacrylate) to obtain a syrup. The nanocomposite sheets were made by bulk polymerization of the syrup in a glass sandwich cell using 2,2′‐azobisisobutyronitrile as initiator. The molar masses and molar mass distributions of synthesized poly(methyl methacrylate) samples were determined by gel permeation chromatography. The content of unreacted double bonds in synthesized samples was determined by 1H NMR spectroscopy. The influence of TiO2 nanoparticles on the thermal stability of the poly(methyl methacrylate) matrix was investigated using thermogravimetric analysis and differential scanning calorimetry. The synthesized samples of poly(methyl methacrylate) have different molar mass and polydispersity depending on the content of the surface modified TiO2 nanoparticles. The values of glass transition temperature of so prepared nanocomposite samples were lower than for pure poly(methyl methacrylate), while the glass transition temperature of samples preheated in inert atmosphere was very similar to the glass transition temperature of pure poly(methyl methacrylate). The thermal stability of nanocomposite samples in nitrogen and air was different from thermal stability of pure poly(methyl methacrylate). POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Blocking and detection chemistries affect antibody performance on reverse phase protein arrays
Authors: Ambroz Kristi L. H. , Zhang Yonghong , Schutz‐Geschwender Amy , Olive D. Michael
Published: June 2008

Antibody specificity is critical for RP protein arrays (RPA). The effects of blocking and detection chemistries on antibody specificity were evaluated for Western blots and RPA. Blocking buffers significantly affected nonspecific banding on Western blots, with corresponding effects on arrays. Tyramide signal amplification (TSA) increased both specific and nonspecific signals on Westerns and arrays, masking the expected gradations in signal intensity. These results suggest that consistent blocking and detection conditions should be used for antibody validation and subsequent RPA experiments.
Proteomic analysis of zygote and ookinete stages of the avian malaria parasite Plasmodium gallinaceum delineates the homologous proteomes of the lethal human malaria parasite Plasmodium falciparum
Authors: Patra Kailash P. , Johnson Jeff R. , Cantin Greg T. , Yates John R. , Vinetz Joseph M.
Published: June 2008

Delineation of the complement of proteins comprising the zygote and ookinete, the early developmental stages of Plasmodium within the mosquito midgut, is fundamental to understand initial molecular parasite‐vector interactions. The published proteome of Plasmodium falciparum does not include analysis of the zygote/ookinete stages, nor does that of P. berghei include the zygote stage or secreted proteins. P. gallinaceum zygote, ookinete, and ookinete‐secreted/released protein samples were prepared and subjected to Multidimensional protein identification technology (MudPIT). Peptides of P. gallinaceum zygote, ookinete, and ookinete‐secreted proteins were identified by MS/MS, mapped to ORFs (>50 amino acids) in the extent P. gallinaceum whole genome sequence, and then matched to homologous ORFs in P. falciparum. A total of 966 P. falciparum ORFs encoding orthologous proteins were identified; just over 40% of these predicted proteins were found to be hypothetical. A majority of putative proteins with predicted secretory signal peptides or transmembrane domains were hypothetical proteins. This analysis provides a more comprehensive view of the hitherto unknown proteome of the early mosquito midgut stages of P. falciparum. The results underpin more robust study of Plasmodium–mosquito midgut interactions, fundamental to the development of novel strategies of blocking malaria transmission.
Plasmodium lipid rafts contain proteins implicated in vesicular trafficking and signalling as well as members of the PIR superfamily, potentially implicated in host immune system interactions
Authors: Di Girolamo Francesco , Raggi Carla , Birago Cecilia , Pizzi Elisabetta , Lalle Marco , Picci Leonardo , Pace Tomasino , Bachi Angela , de Jong Joke , Janse Chris J. , Waters Andrew P. , Sargiacomo Massimo , Ponzi Marta
Published: June 2008

Plasmodium parasites, the causal agents of malaria, dramatically modify the infected erythrocyte by exporting parasite proteins into one or multiple erythrocyte compartments, the cytoplasm and the plasma membrane or beyond. Despite advances in defining signals and specific cellular compartments implicated in protein trafficking in Plasmodium‐infected erythrocytes, the contribution of lipid‐mediated sorting to this cellular process has been poorly investigated. In this study, we examined the proteome of cholesterol‐rich membrane microdomains or lipid rafts, purified from erythrocytes infected by the rodent parasite Plasmodium berghei. Besides structural proteins associated with invasive forms, we detected chaperones, proteins implicated in vesicular trafficking, membrane fusion events and signalling. Interestingly, the raft proteome of mixed P. berghei blood stages included proteins encoded by members of a large family (bir) of putative variant antigens potentially implicated in host immune system interactions and targeted to the surface of the host erythrocytes. The generation of transgenic parasites expressing BIR/GFP fusions confirmed the dynamic association of members of this protein family with membrane microdomains. Our results indicated that lipid rafts in Plasmodium‐infected erythrocytes might constitute a route to sort and fold parasite proteins directed to various host cell compartments including the cell surface.
Altered expression of calreticulin during the development of fibrosis
Authors: Kypreou Katerina P. , Kavvadas Panagiotis , Karamessinis Panagiotis , Peroulis Michalis , Alberti Avra , Sideras Paschalis , Psarras Stelios , Capetanaki Yasemie , Politis Panagiotis K. , Charonis Aristidis S.
Published: June 2008

Tissue damage following injury leads to inflammation and fibrosis. To understand the molecular mechanisms and the proteins involved in the fibrotic process, we used the well‐established unilateral ureteric obstruction rat model and we analyzed the alterations at early and late time intervals using a classical proteomic approach. Data analysis demonstrates a correlation between calreticulin up‐regulation and progression of fibrosis. Calreticulin is involved in Ca++ homeostasis but has not been previously implicated in animal models of fibrosis. Proteomic analysis consistently revealed up‐regulation of calreticulin in both early and late time intervals. These findings were further confirmed by biochemical and morphological approaches. Next, animal models of lung fibrosis (bleomycin‐induced) and heart fibrosis (desmin‐null) were examined. In the lung model, calreticulin expression was up‐regulated from early time intervals, whereas in the heart model no change in the expression of calreticulin was observed. In addition, TGF‐β, a well known major contributing factor in several fibrotic processes, was found to up‐regulate calreticulin in cultured human proximal tubule epithelial cells. The above observations suggest that calreticulin might be involved in fibrotic processes; however the mechanism(s) underlying its possible involvement are yet unresolved.
Mitochondrial ATP synthase is a target for TNBS‐induced protein carbonylation in XS‐106 dendritic cells
Authors: Je Jeong Hwan , Lee Tae Hyung , Kim Dong Hyun , Cho Young Hun , Lee Ju Hee , Kim Soo Chan , Lee Sang‐Kyou , Lee Jaewon , Lee Min‐Geol
Published: June 2008

ROS are produced in dendritic cells (DCs) during antigen presentation in contact hypersensitivity (CHS). As a result, ROS cause a number of nonenzymatic protein modifications, including carbonylation, which is the most widely used marker of oxidative stress. 2,4,6‐Trinitrobenzene sulfonic acid (TNBS) is a well‐characterized contact allergen that results in the formation of ROS. However, proteins that are carbonylated in DCs in response to TNBS have not been identified. To study ROS‐dependent protein carbonylation in response to TNBS, we used the well‐established mouse DC line, XS‐106. We focused on the effects of TNBS on oxidation by examining selected oxidative markers. We identified TNBS‐induced ROS and myeloperoxidase (MPO) proteins and demonstrated that the increase in ROS resulted in IL‐12 production. The increase in oxidation was further confirmed by an oxidation‐dependent increase in protein modifications, such as carbonylation. In fact, TNBS strongly induced carbonylation of mitochondrial adenosine triphosphate (ATP) synthase in XS‐106 DCs, as determined by MALDI‐TOF analysis and 2‐D Western blotting. ROS production and protein carbonylation were confirmed in human monocyte‐derived DCs (Mo‐DCs). Furthermore, glutathione (GSH) decreased ROS and protein carbonylation in Mo‐DCs. Carbonylation of ATP synthase in DCs may contribute to the pathophysiology of CHS.
Proteomic analysis of exoproteins expressed by enterotoxigenic Staphylococcus aureus strains
Authors: Pocsfalvi Gabriella , Cacace Giuseppina , Cuccurullo Manuela , Serluca Giovanna , Sorrentino Alida , Schlosser Gitta , Blaiotta Giuseppe , Malorni Antonio
Published: June 2008

Pathogenic bacteria excrete a variety of virulence factors into extracellular medium and to the cell surface which have essential roles in the colonization and insurrection of the host cells, and thus reflect the degree of bacterial pathogenicity. For the exploration of virulence factors expressed in the secreted proteome fraction, different Staphylococcus aureus strains were analyzed using gel‐based bottom‐up proteomic approach. A total of 119 distinct proteins were identified for the enterotoxin gene cluster (egc) negative and seb gene positive S. aureus American Type Culture Collection (ATCC) 14458 strain by the use of one‐ and 2‐DE based proteomics. Detailed analysis of enterotoxin region of the 2‐D map confirmed, beside the highly expressed staphylococcal enterotoxin B (SEB), the presence of enterotoxin‐like proteins SElK and SElQ previously predicted by genotyping (Sergeev et al.., J. Clin. Microbiol. 2004, 42, 2134–2143). Exoprotein patterns at the late‐exponential (7 h) and stationary (24 h) phases of cellular growth show a high‐level similarity in this region. Comparative analysis of enterotoxin region of five S. aureus strains including two clinical isolates (RIMD 31092 and A900322), a food derived strain (AB‐8802) with highly prevalent egc positive operon and a nonenterotoxigenic reference strain (ROS) revealed the presence of different known enterotoxins and other virulence factors along with a number of core exoproteins. In addition, production of SElL (RIMD 31092) and SElP (A900322) was demonstrated for the first time at the protein level. Under the experimental conditions applied none of the enterotoxins encoded by the genes of egc operon was identified.