bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of myocardial infarction in pigs using a rapid clearance blood pool contrast medium
Authors: Dewey Marc , Kaufels Nicola , Laule Michael , Schnorr Jörg , Wagner Susanne , Kivelitz Dietmar , Raynaud Jean‐Sébastien , Robert Philippe , Hamm Bernd , Taupitz Matthias
Published: March 2004

Delayed enhancement MRI using extracellular contrast media allows reliable detection of myocardial infarction. If blood pool contrast media like P792 (Vistarem, Guerbet, France), in addition to improving coronary MR angiography, can be shown to also produce delayed enhancement in myocardial infarction they could improve the prerequisites for a comprehensive cardiac MR examination. In this study reperfused myocardial infarction in five minipigs was imaged with an inversion‐recovery fast low‐angle shot sequence using P792 (0.013 mmol Gd/kg) and the extracellular contrast medium Gd‐DOTA (Dotarem, 0.1 mmol Gd/kg, Guerbet). The infarction size determined on MRI using P792 (7.55 ± 2.31 cm2) highly correlated both with histomorphometry (7.81 ± 2.18 cm2, r = 0.991, P < 0.002) and with MRI using Gd‐DOTA (7.85 ± 2.35 cm2, r = 0.978, P < 0.005). Bland‐Altman analysis showed that the limit of agreement of MRI using P792 compared to histomorphometry was 3.3 ± 7.6% of the infarction size. The contrast‐to‐noise ratio between infarcted and remote myocardium was not significantly different between Gd‐DOTA (5.9 ± 2.4) and P792 (4.4 ± 1.1, P = 0.5). The blood pool contrast medium P792 allows reliable assessment of viability with good contrast and accuracy. Magn Reson Med 51:703–709, 2004. © 2004 Wiley‐Liss, Inc.
Active device tracking and high‐resolution intravascular MRI using a novel catheter‐based, opposed‐solenoid phased array coil
Authors: Hillenbrand Claudia M. , Elgort Daniel R. , Wong Eddy Y. , Reykowski Arne , Wacker Frank K. , Lewin Jonathan S. , Duerk Jeffrey L.
Published: March 2004

A novel two‐element, catheter‐based phased array coil was designed and built for both active MR device tracking and high‐resolution vessel wall imaging. The device consists of two independent solenoid coils that are wound in opposite directions, connected to separate receive channels, and mounted collinearly on an angiographic catheter. The elements were used independently or together for tracking or imaging applications, respectively. The array's dual functionality was tested on a clinical 1.5 T MRI scanner in vitro, in vivo, and in situ. During real‐time catheter tracking, each element gave rise to a high‐amplitude peak in the respective projection data, which enabled reliable and robust device tracking as well as automated slice positioning. In vivo microimaging with 240 μm in‐plane resolution was achieved in 9 s using the device and TrueFISP imaging. Therefore, a single device was successfully implemented that met the combined requirements of intravascular device tracking and imaging. Magn Reson Med 51:668–675, 2004. © 2004 Wiley‐Liss, Inc.
Real‐time cardiac MRI at 3 tesla
Authors: Nayak Krishna S. , Cunningham Charles H. , Santos Juan M. , Pauly John M.
Published: March 2004

Real‐time cardiac and coronary MRI at 1.5T is relatively “signal starved” and the 3T platform is attractive for its immediate factor of two increase in magnetization. Cardiac imaging at 3T, however, is both subtly and significantly different from imaging at 1.5T because of increased susceptibility artifacts, differences in tissue relaxation, and RF homogeneity issues. New RF excitation and pulse sequence designs are presented which deal with the fat‐suppression requirements and off‐resonance issues at 3T. Real‐time cardiac imaging at 3T is demonstrated with high blood SNR, blood‐myocardium CNR, resolution, and image quality, using new spectral‐spatial RF pulses and fast spiral gradient echo pulse sequences. The proposed sequence achieves 1.5 mm in‐plane resolution over a 20 cm FOV, with a 5.52 mm measured slice thickness and 32 dB of lipid suppression. Complete images are acquired every 120 ms and are reconstructed and displayed at 24 frames/sec using a sliding window. Results from healthy volunteers show improved image quality, a 53% improvement in blood SNR efficiency, and a 232% improvement in blood‐myocardium CNR efficiency compared to 1.5T. Magn Reson Med 51:655–660, 2004. © 2004 Wiley‐Liss, Inc.
Inversion recovery TrueFISP: Quantification of T1, T2, and spin density
Authors: Schmitt Peter , Griswold Mark A. , Jakob Peter M. , Kotas Markus , Gulani Vikas , Flentje Michael , Haase Axel
Published: March 2004

A novel procedure is proposed to extract T1, T2, and relative spin density from the signal time course sampled with a series of TrueFISP images after spin inversion. Generally, the recovery of the magnetization during continuous TrueFISP imaging can be described in good approximation by a three parameter monoexponential function S(t) = Sstst(1‐INV exp(‐t/T). This apparent relaxation time T ≤ T1 depends on the flip angle as well as on both T1 and T2. Here, it is shown that the ratio T1/T2 can be directly extracted from the inversion factor INV, which describes the relation of the signal value extrapolated to t = 0 and the steady‐state signal. Analytical expressions are given for the derivation of T1, T2, and relative spin density directly from the fit parameters. Phantom results show excellent agreement with single point reference measurements. In human volunteers T1, T2, and spin density maps in agreement with literature values were obtained. Magn Reson Med 51:661–667, 2004. © 2004 Wiley‐Liss, Inc.
Handling constraints using multiobjective optimization concepts
Authors: Aguirre Arturo Hernández , Rionda Salvador Botello , Coello Coello Carlos A. , Lizárraga Giovanni Lizárraga , Montes Efrén Mezura
Published: March 2004

In this paper, we propose a new constraint‐handling technique for evolutionary algorithms which we call inverted‐shrinkable PAES (IS‐PAES). This approach combines the use of multiobjective optimization concepts with a mechanism that focuses the search effort onto specific areas of the feasible region by shrinking the constrained search space. IS‐PAES also uses an adaptive grid to store the solutions found, but has a more efficient memory‐management scheme than its ancestor (the Pareto archived evolution strategy for multiobjective optimization). The proposed approach is validated using several examples taken from the standard evolutionary and engineering optimization literature. Comparisons are provided with respect to the stochastic ranking method (one of the most competitive constraint‐handling approaches used with evolutionary algorithms currently available) and with respect to other four multiobjective‐based constraint‐handling techniques. Copyright© 2004 John Wiley & Sons, Ltd.
A fast boundary cloud method for 3D exterior electrostatic analysis
Authors: Shrivastava Vaishali , Aluru N. R.
Published: March 2004

An accelerated boundary cloud method (BCM) for boundary‐only analysis of 3D electrostatic problems is presented here. BCM uses scattered points unlike the classical boundary element method (BEM) which uses boundary elements to discretize the surface of the conductors. BCM combines the weighted least‐squares approach for the construction of approximation functions with a boundary integral formulation for the governing equations. A linear base interpolating polynomial that can vary from cloud to cloud is employed. The boundary integrals are computed by using a cell structure and different schemes have been used to evaluate the weakly singular and non‐singular integrals. A singular value decomposition (SVD) based acceleration technique is employed to solve the dense linear system of equations arising in BCM. The performance of BCM is compared with BEM for several 3D examples. Copyright © 2004 John Wiley & Sons, Ltd.
Preparation of N‐n‐Octyl‐D‐glucamine by the catalytic hydrogenation with palladium complex of MgO‐supported melamine‐formaldehyde polymer
Authors: Liu Pu , Zhu Weiwei
Published: March 2004

The palladium complex of MgO‐supported melamine‐formaldehyde polymer catalyst was prepared and characterized by X‐ray diffraction (XRD) and X‐ray photoelectron spectroscopy (XPS). The preparation of N‐n‐octyl‐D‐glucamine was investigated by using this complex as the catalyst. It was found that the palladium complex of MgO‐supported melamine‐formaldehyde polymer has a good catalytic activity for the hydrogenation of n‐octylamine with D‐glucose to produce N‐n‐octyl‐D‐glucamine. The effects of additive, solvent, temperature, hydrogen pressure, Pd content in the catalyst and the amount of catalyst on the preparation of N‐n‐octyl‐D‐glucamine have all been studied. Under the optimum experimental conditions—D‐glucose, 37.2 mmol; n‐octylamine, 31 mmol; triethylamine, 1.0 ml; ethanol, 60 ml; temperature, 333 K; hydrogen pressure, 1.5 MPa; the amount of the catalyst (Pd content 3.55%, N/Pd molar ratio 12), 0.7 g—the highest yield of N‐n‐octyl‐D‐glucamine (57.6%) was obtained. XRD results show that melamine‐formaldehyde polymer changed the structure of MgO, and XPS results suggest that coordination bonds were formed between the hexatomic ring and metal atom, and palladium particles were immobilized on the polymer. Copyright © 2004 John Wiley & Sons, Ltd.
Polystyrene prepared by reactive extrusion: kinetics and effect of processing parameters
Authors: Shishuang Gao , Ying Zhang , Anna Zheng , Xiao Huining
Published: March 2004

The conversion and residence time were investigated during the bulk polymerization of styrene in a twin screw extruder. It was found that polymerization mainly occurred in the zone between 400 and 1000 mm along the screw axis in the extruder, corresponding to the residence time of the reactants ranging from 1 to 4 min in the extruder. Furthermore, the processing conditions (feed rate, screw rotation rate) and average molecular weight of the polymer have a great effect on the residence time. Based on dimensionless analysis, a model of the residence time has been built‐up, which has been confirmed by the results of realistic measurements. A kinetic model of the polymerization has also been established under the assumption that the screw extruder can be regarded as an ideal plug flow reactor. Copyright © 2004 John Wiley & Sons, Ltd.
The role of thiophosphoryl disulfide on the co‐cure of CR‐EPDM blends
Authors: Das Amit , Ghosh Arup Kumar , Pal Sudipta , Basu Dipak Kumar
Published: March 2004

Bis(diisopropyl)thiophosphoryl disulfide (DIPDIS) has been used as a coupling cum curing agent for the compatibilization of blends of ethylene propylene diene monomer rubber (EPDM) with chloroprene rubber (CR). Electrical and mechanical properties of the blend vulcanizates have been studied to find the efficiency of the vulcanizing cum coupling activity of DIPDIS. The study reveals that CR in the presence of DIPDIS greatly improves the physical properties of EPDM. It is noted that the physical properties of the vulcanizates obtained from CR‐EPDM blend depend upon CR:EPDM ratio. The scanning electron microscopy (SEM) study reveals that it is possible to form a coherent blend of CR and EPDM in the presence of DIPDIS. Copyright © 2004 John Wiley & Sons, Ltd.
Effect of maleic anhydride and liquid natural rubber as compatibilizers on the mechanical properties and impact resistance of the NR‐NBR blend
Authors: Mounir Ahmed , Darwish Nabila A. , Shehata Adel
Published: March 2004

The degree of compatibilization between natural rubber (NR) and acrylonitrile‐butadiene rubber (NBR) was investigated by two different methods. NBR was chemically modified with maleic anhydride in a screw twin mixer with and without reaction initiator, benzoyl peroxide. Also, the effects of molecular weight of liquid natural rubber (LNR) as a compatibilizer were studied. The degree of compatibilization between NBR and NR is determined indirectly through measurements of mechanical properties and impact resistance. The maleic anhydride and benzoyl peroxide concentrations influence the mechanical properties and impact resistance of the blends. Also, the mechanical properties of the blends showed that the molecular weight of LNR played an important role in determing their performance. Copyright © 2004 John Wiley & Sons, Ltd.
A novel hyperbranched polyester acrylate used for microfabrications
Authors: Kou Huiguang , Asif Anila , Shi Wenfang , Jiang Zhongwei , Huang Wenhao
Published: March 2004

A novel hyperbranched polyester acrylate (HPEA) was synthesized based upon ethylenediamine tetraacetic acid as a “core” molecule, 5‐hydroxyisophthalic acid as an AB2 monomer, and 2‐hydroxyethyl acrylate as an endcapping reagent. The obtained oligomer has an unsaturation concentration of 4.10 mmolCC g−1 measured by nuclear magnetic resonance and a wide molecular weight distribution of 1.64 measured by gel permeation chromatography. The two‐photon absorption (TPA) photopolymerization of HPEA under the exposure of a Ti : sapphire femtosecond laser with a wavelength of 800 nm was investigated through laser exposure dose‐dependant spatial resolutions of its resins. The TPA photopolymerization thresholds at the range 1.6–4.3 × 107 mJ cm−2, and exposure dose windows at the range 3.4–4.3 for three formulations were determined. A spatial resolution of 0.85 μm was obtained through the TPA photopolymerization of the formulation containing 1 wt% photoinitiator and 0.3 wt% photoinhibitor. A diffraction grating and real three‐dimensional coupled gear wheel created by TPA photopolymerization were described to demonstrate the unique capability of HPEA in microfabrications. Copyright © 2004 John Wiley & Sons, Ltd.
Study of interphase in glass fiber–reinforced poly(butylene terephthalate) composites
Authors: Bergeret A. , Bozec M. P. , Quantin J.‐C. , Crespy A. , Gasca J.‐P. , Arpin M.
Published: March 2004

It is well known that application of a coupling agent to a glass fiber surface will improve fiber/matrix adhesion in composites. However, on commercial glass fibers the coupling agent forms only a small fraction of the coating, the larger part being a mixture of processing aids whose contribution to composite properties is not well defined. The interfacial region of the composite will therefore be affected by the coating composition but also by the chemical reactions involved in the vicinity of the fiber and inside the surrounding matrix. The main feature of this study consists in dividing the interface region into two separate regions: the fiber/sizing interphase and the sizing/matrix interphase. A wide range of techniques was used, including mechanical and thermomechanical tests, infrared spectroscopy, gel permeation chromatography, carboxyl end group titrations, extraction rate measurements, and viscosity analysis. Experiments were performed on poly(butylene terephthalate) composites and results indicate that the adhesion improvement is due to the presence of a short chain coupling agent and of a polyfunctional additive, which may react both with the coupling agent and the matrix. According to the nature of this additive, it may be possible to soften the interphase and then to increase the composite impact strength.
Thermal control system for thick composite laminates based on forecasting
Authors: Shin Daniel D. , Hahn H. Thomas
Published: March 2004

A forecast‐based thermal control system was developed to cure thick composite laminates that produced large exothermic reactions. The system used process simulation models for heat transfer and compaction to predict future cure conditions at a designated forecast time so that the system can respond to avoid approaching adverse conditions. The thermal control system derived cure cycles that eliminated exotherms and maintained uniform through‐the‐thickness temperature gradient for 3‐cm thick AS4/35016 laminates. The on‐line results indicated that cure cycles were slightly different from off‐line simulation results, mainly because of the slow response of the hot press. Nevertheless the system was able to satisfy the cure criteria under such unforeseen circumstances, which demonstrated the flexibility of the forecasting method.
Effects of styrene‐isoprene copolymer glass fiber coatings on woven glass cloth epoxy composite performance
Authors: Blakley Kevin L. , Grady Brian P. , O'Rear Edgar A.
Published: March 2004

Woven glass‐epoxy composites were prepared from mats that had been treated in a variety of ways. Fibers were coated with a commercial sizing, no sizing, and a surfactant coating. In addition, fibers were coated with styrene‐isoprene copolymers at varying molar ratios using a novel technique termed admicellar polymerization. Dynamic contact angle measurements were used to quantify the effect of the different coating techniques on the fiber, while dynamic mechanical analysis (DMA) and flexural testing were used to characterize the cured composites. Wetting studies conducted with EPON 828 resin revealed no difference in wetting for the polymer‐treated fiber compared to the commercially‐treated fiber. Aqueous wetting results were consistent with a surfactant layer adsorbed on the polymer treated and surfactant treated fiber surface. DMA established that both the polymer and surfactant treatment depressed the alpha transition temperature of the composite and suggested an interpenetrating network existed at the fiber‐matrix interface. Flexural strength testing showed the properties of the composites made from surfactant‐treated and polymer‐treated glass fibers were comparable to composites made from commercially‐sized fibers and exceeded the flexural strength of the composite made from glass fibers without sizing.
The effect of steel fiber orientation on frictional properties of asbestos‐free friction materials
Authors: Qu Xiongwei , Zhang Liucheng , Ding Huili , Liu Guodong
Published: March 2004

The frictional properties of the composites reinforced with continuous steel fibers have been evaluated in LNBR modified phenolic resin based friction materials. The fiber orientations are introduced regarding the sliding direction, i.e. parallel (P) along the fiber direction, normal (N) and antiparallel (AP). The specific wear rates are increased if the sliding path is shifted from the P to the AP and N direction. The coefficient of friction is also dependent on the fiber alignment directions. The coefficients of these materials fall in the range of 0.49 to 0.54. The initial sliding interaction is plowing action if the turnplate temperature is below 250°C. Meanwhile, with the increase of the temperature, as ironed transfer film developed on the specimen, the interaction became adhesive and steady‐state friction is established. The wear resistance of the composite is found to relate to the stability of the film.
Diabetes in the young: past, present and future
Authors: Swift PGF
Published: March 2004

Optimal management of diabetes in children and adolescents continues to present difficult challenges. Constant and unpredictable changes in growth, development and physiological maturity are compounded by problems of brittle families, social and cultural habits and behavioural upheavals. The dilemma of balancing metabolic control against quality of life is accentuated in childhood.

Adverse societal influences sabotage attempts at achieving good glycaemic control and cardiovascular protection. UK children often have unstructured meal patterns, eat poor quality food (high in saturated fats) and consume excessive sweet foods.

To counterbalance increasing expectations of improved metabolic control there is an ever increasing incidence of type 1 diabetes, the emerging numbers of type 2 and rising numbers of secondary causes of diabetes in the larger children's diabetic clinics.

National surveys of children's services have shown considerable improvements but major deficiencies remain. Outcomes in the UK in terms of metabolic control do not compare favourably with some international centres and the challenges for the future include improvements in the organisation of care, staffing levels and structures, and improved collaboration between children's and adult services in expanded centres of excellence for the management of childhood diabetes. Copyright © 2004 John Wiley & Sons, Ltd.
Nutritional advice for people with diabetes: past, present, what next?
Authors: Thomas B
Published: March 2004

The dietary management of diabetes has undergone enormous change in the last 20 years following the realisation that inflexible regimens dominated by carbohydrate and sucrose restriction were inappropriate. Modem dietary guidelines aim to optimise not just the management of glycaemia but other parameters which influence microvascular and cardiovascular risk such as dyslipidaemia, adiposity and hypertension. Patients are no longer expected to follow standardised diets, but are encouraged to make adjustments to existing eating habits in a way which achieves permanent and beneficial change. Future management is likely to be dominated by the rising prevalence of type 2 diabetes in both adults and children and the need to find effective ways of preventing and correcting obesity. Copyright © 2004 John Wiley & Sons, Ltd.
Vascular disease and diabetes: the change in emphasis in the last 20 years
Authors: Fisher M
Published: March 2004

The approach to vascular disease in people with diabetes has been transformed in the last 20 years. Epidemiological studies have confirmed the excessive morbidity and mortality from cardiovascular disease in type 2, and more recently in type 1, diabetes. Many pharmacological studies have shown that this excess risk can be reduced by reduction of blood pressure or cholesterol, but blood glucose lowering studies have been few in number and disappointing in vascular outcomes. Modern cardiological interventions are also beneficial in this high‐risk group of patients. Looking forward to the next 20 years, two key areas for further study can be identified: a greater understanding of the pathophysiology, prevention and treatment of vascular disease in type 1 diabetes, and more information on the pathophysiology and treatment of stroke disease in all forms of diabetes. Copyright © 2004 John Wiley & Sons, Ltd.
Diabetes care in Brazil: now and in the future
Authors: Pedrosa HC
Published: March 2004

Brazil, like many other developing countries, faces the dual problem of an increasing burden of chronic disease together with many communicable diseases. The organisation of diabetes care and the provision of drugs have improved considerably over the last 20 years, and the Brazilian Diabetes Society has had a major role in these improvements. However, many people remain unaware that they have diabetes and some diagnosed patients receive no treatment. Copyright © 2004 John Wiley & Sons, Ltd.
Diabetes care in The Netherlands: now and in the future
Authors: Bakker K , Bilo Henk JG
Published: March 2004

The prevalence of diabetes mellitus (DM)‐in The Netherlands is rapidly increasing. In 2000, the total number of people with DM is estimated at 462‐000 out of a total of 16 million inhabitants. The rapid growth is especially found in the group with type 2 DM (85%). The financial burden of direct and indirect costs is high. Access to care is at present easily available and almost fully reimbursable. Most hospital organisations have diabetes teams available for type I DM patients. The care for type 2 DM is mainly concentrated in primary care. The role of diabetes specialist nurses and podiatrists has grown in importance in the last decade. Guidelines on care and prevention are amply available but not fully implemented. A nationwide reduction (34%) on lower extremity amputations during the last 10 years has been reported recently. Looking at the future, shared care initiatives are underway. There are concerns about the rapid growth in prevalence, the increase of obesity and the possible shortage of general practitioners. Copyright © 2004 John Wiley & Sons, Ltd.
Analysis of gate freeze‐off time in injection molding
Authors: Pantani R. , De Santis F. , Brucato V. , Titomanlio G.
Published: March 2004

Gate solidification time is an important topic in injection molding technology, as it determines cycle time, which itself is an important issue in the balance of the production process. In this work, a study of the effect of both gate and cavity geometries on gate solidification time was conducted, using a commercial polymer, injection molded with constant holding pressure into a rectangular cavity. Three cavity lengths were used, and for each, two cavity thicknesses were adopted. Special dies containing different gates were assembled in the mold. Gate thickness was found to be the most important factor determining gate sealing time. However the cavity geometry is also quite important. A clear indication on gate solidification could be drawn by analyzing time evolution of pressure distribution inside the mold. The solidification phenomenon leading to gate sealing was analyzed by a simple model, which also takes into account the effect of cavity geometry, by comparing the heat flow through the gate walls and the energy required to solidify the packing flow rate. Model results satisfactorily describe the main features of the experimental data.
Measurement of interfacial tension in PS/LDPE melts saturated with supercritical CO2
Authors: Xue Anle , Tzoganakis Costas , Chen Pu
Published: March 2004

The effect of supercritical carbon dioxide (scCO2) on the interfacial tension between a polymer melt pair—polystyrene (PS) and low density polyethylene (LDPE)—was studied using the pendant drop method at temperatures varying from 200 to 240°C and CO2 pressures up to 18 MPa. The LDPE melt was prepared in a high pressure optical cell and the PS pendant drop was injected into the LDPE melt with a special high pressure syringe. For measurements with scCO2, the optical cell was first pressurized with scCO2 and measurements were taken after the saturation of scCO2 into both polymer melts. Excellent agreement was found with literature data for the same system without using scCO2. For the polymer pair saturated with scCO2, it was found that the interfacial tension decreases significantly with increasing CO2 pressure and appears to level off at higher CO2 pressures.
Surface characteristics of hydrosilylated polypropylenes: Effect of co‐catalyst and reaction temperature
Authors: Long J. , Tzoganakis C. , Chen P.
Published: March 2004

Polypropylene (PP) was modified through a peroxide‐induced degradation and a catalytic hydrosilylation reaction in the melt phase. The effects of temperature and co‐catalysts on the reaction and the surface characteristics of the hydrosilylated polypropylene (SiPP) were studied. Axisymmetric Drop Shape Analysis‐Profile (ADSA‐P) was used to characterize the surface wettability. The morphology, roughness and heterogeneity of the surface were investigated by the lateral force mode of atomic force microscopy (LFM). Proton nuclear magnetic resonance (1H NMR) spectroscopy was employed to quantify the conversion of terminal double bonds. X‐ray photoelectron spectroscopy (XPS) was used to quantify the surface chemical composition. LFM images showed that the surfaces of the PP and DPP samples were rough but heterogeneous and that the surfaces of the SiPP samples appeared rough but homogeneous. The surface wettability was well correlated to the surface microstructure and surface chemical composition. The surfaces investigated were modeled based on the microstructure observed, and a new scheme was developed to calculate surface free energy and adhesion work. Results showed that there is an optimum reaction temperature in terms of the conversion of double bonds, and that increasing the amount of co‐catalyst promotes the conversion.
Variations in surface gloss on rubber‐modified thermoplastics: Relation to morphological and rheological behavior
Authors: Edwards S. A. , Roy Choudhury N.
Published: March 2004

The parameters that promote the formation of surface defects on multi‐phase polymer systems during injection molding are not yet clearly understood. The objective of this work is to establish the influence of composition, particularly the role of rubber, on the rheological properties of such multi‐phase systems and relate that to variations in gloss that appear on the surface of ASA and PC/ASA blends. Analysis of morphology by micro‐thermal analysis (μTA™) in combination with oscillatory rheology, time‐temperature‐superposition (TTS), creep recovery and PVT testing revealed distinct trends of surface gloss with each material's viscoelastic behavior and surface finish. It has been shown that influential properties such as rubber content, particle size and distribution, molecular weight, viscosity ratios and the degree of acrylonitrile mismatching play key roles in each material's rheology, developed morphology and subsequent trends in surface gloss after injection molding.
On the modeling of quiescent crystallization of polymer melts
Authors: Rao I. J. , Rajagopal K. R.
Published: March 2004

In this paper we present a way of modeling crystallization in polymers within the confines of a new general framework that has been developed to describe materials undergoing dissipative processes. Crystallization in polymers is in general an irreversible process, and a characteristic of all such processes is the production of entropy. In addition to postulating constitutive forms for the internal energy and entropy, we prescribe a constitutive relation for the entropy production. This in turn aids in deriving the crystallization rate equation from the second law, under the constraint that all real processes tend to maximize the rate of entropy production. After developing the general framework we derive specific models and compare the predictions of the model against experimental data available for quiescent crystallization in the literature. The predictions of the theory compare very well with the available experimental data for Nylon‐6 obtained by Patel and Spruiell (1).
Color of pigmented plastics—Measurements and predictions
Authors: Ariño Ingrid , Kleist Ulf , Rigdahl Mikael
Published: March 2004

The effect of the concentration of a colorant (masterbatch) and the surface texture on the color of an opaque injection‐molded plaque is experimentally described by means of the spectral reflectance and the CIELAB coordinates. It was noted that the surface texture had a marked influence on the experimental results and on the perceived color. The relation between the color of these pigmented plastic plaques and intrinsic physical material properties, such as light absorption and scattering coefficients, is described by means of the Kubelka‐Munk equation for pigment/paste mixtures. The concentration dependence of this Kubelka‐Munk equation for different masterbatch‐polymer mixtures can be modeled in terms of the color of the individual constituents using a fitting parameter. Further experiments were carried out which indicated that the fitting parameter had a physical meaning. The effect of the surface texture on the optical appearance of the plaques can also be accounted for by this parameter.
Shear rate and wall slip velocity functions of polyvinyl chloride melts based on slit die viscometry data
Authors: Yeow Y. Leong , Leong Yee‐Kwong
Published: March 2004

Shear stress versus shear rate and wall shear stress versus slip velocity relations of polymer melts are key material property functions needed in the design of polymer processing equipment. These properties are normally measured using capillary or slit viscometers. The presence of slip greatly complicates the processing of the resulting viscometry data. This paper describes the conversion of the viscometry data of a number of polyvinyl chloride melts through slit dies with different gaps into these two material property functions. The conversion procedure, based on Tikhonov regularization, has the advantage that it is independent of rheological constitutive equation and does not require extrapolation of the experimental data. It also has the ability to cope with the unavoidable noise in the experimental data. Consequently, the property functions thus obtained are likely to be closer to true material properties than those from some of the existing methods. For each of the polyvinyl chloride melts investigated, these properties' functions will be compared with published results and their differences discussed.
A study on sliding wear of ultrahigh molecular weight polyethylene/polypropylene blends
Authors: Liu Gongde , Xiang Ming , Li Huilin
Published: March 2004

The wear and friction behavior of ultrahigh molecular weight polyethylene (UHMWPE)/ polypropylene (PP) blends was studied. The addition of PP improves processability and the anti‐wear properties of UHMWPE. The friction coefficient and wear rate of pure UHMWPE are much higher than those of UHMWPE/PP blends under the same conditions, and the wear rate of UHMWPE is more sensitive to load and wear time than that of the UHMWPE/PP blend. Long scratch grooves and cracks occurred in the worn surface of UHMWPE, while no such serious damage was observed in the worn surface of the UHMWPE/PP blend. Atomic Force Micrograph using the contact mode indicated that the friction force between pure UHMWPE and Si3N4 tip is much higher than that for the UHMWPE/PP blend, which is consistent with the results from macro‐friction testing.
Characterization, morphology, thermal and mechanical properties of conductive polyaniline‐functionalized EPDM elastomers obtained by casting
Authors: Domenech S. C. , Bortoluzzi J. H. , Soldi V. , Franco C. V. , Gronski W. , Radusch H.‐J.
Published: March 2004

Conductive elastomeric blends based on ethylene–propylene–5‐ethylidene–2‐norbornene terpolymer (EPDM) and polyaniline doped with 4‐dodecylbenzenesulfonic acid [PAni(DBSA)] were cast from organic solvents. Functionalization of the elastomer was promoted by grafting with maleic anhydride. Vulcanization conditions were optimized with an oscillating disk rheometer. The conductivity, morphology, thermal stability, compatibility, and mechanical behavior of the obtained mixtures were analyzed by in situ direct current conductivity measurements, atomic force microscopy, transmission electron microscopy, wide‐angle X‐ray scattering, thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical thermal analysis, stress–strain and hysteresis tests. The vulcanization process was affected by temperature, the PAni content, and maleic anhydride. A reinforcement effect was promoted by the vulcanizing agent. The formation of links between the high‐molar‐mass phases and oligomers of PAni(DBSA) in the elastomeric matrix enhanced the thermal stability and ultimate properties of the blends. By the appropriate control of the polymer blends' composition, it was possible to produce elastomeric materials with conductivities in the range of 10−5–10−4 S · cm−1 and excellent mechanical properties. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1767–1782, 2004
Thermal and mechanical properties of syndiotactic polystyrene/organoclay nanocomposites with different microstructures
Authors: Park Cheon Il , Choi Won Mook , Kim Mun Ho , Park O Ok
Published: March 2004

The fabrication of syndiotactic polystyrene (sPS)/organoclay nanocomposite was conducted via a stepwise mixing process with poly(styrene‐co‐vinyloxazolin) (OPS), that is, melt intercalation of OPS into organoclay followed by blending with sPS. The microstructure of nanocomposite mainly depended on the arrangement type of the organic modifier in clay gallery. When organoclays that have a lateral bilayer arrangement were used, an exfoliated structure was obtained, whereas an intercalated structure was obtained when organoclay with a paraffinic monolayer arrangement were used. The thermal and mechanical properties of sPS nanocomposites were investigated in relation to their microstructures. From the thermograms of nonisothermal crystallization and melting, nanocomposites exhibited an enhanced overall crystallization rate but had less reduced crystallinity than a matrix polymer. Clay layers dispersed in a matrix polymer may serve as a nucleating agent and hinder the crystal growth of polymer chains. As a comparison of the two nanocomposites with different microstructures, because of the high degree of dispersion of its clay layer the exfoliated nanocomposite exhibited a faster crystallization rate and a lower degree of crystallinity than the intercalated one. Nanocomposites exhibited higher mechanical properties, such as strength and stiffness, than the matrix polymer as observed in the dynamic mechanical analysis and tensile tests. Exfoliated nanocomposites showed more enhanced mechanical properties than intercalated ones because of the uniformly dispersed clay layers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1685–1693, 2004
Fracture morphology and mechanical properties of ethylene/vinyl acetate rubber vulcanizates reinforced by in situ prepared sodium methacrylate
Authors: Du Aihua , Peng Zonglin , Zhang Yong , Zhang Yinxi
Published: March 2004

Ethylene/vinyl acetate rubber (EVM) was reinforced by sodium methacrylate (NaMAA) that was in situ prepared through the neutralization of sodium hydroxide and methacrylic acid in EVM during mixing. The mechanical properties of EVM vulcanizates with different NaMAA loadings and at different crosslink densities were studied and compared with those of high abrasion furnace carbon black (HAF) filled EVM vulcanizates. The fracture surfaces of gum and filled EVM vulcanizates were observed with scanning electron microscopy. The results showed that NaMAA‐reinforced EVM vulcanizates had better mechanical properties than HAF/EVM vulcanizates. When the NaMAA loading was 50 phr, the tensile strength of the NaMAA/EVM vulcanizate was 30 MPa, the tear strength was 102 kN/m, and the elongation at break was over 400%. Fourier transform infrared analysis confirmed that NaMAA formed in the compounding process and underwent polymerization during vulcanization. Scanning probe microscopy analysis revealed that nanoscale particles dispersed in the NaMAA/EVM vulcanizates. The mechanical properties were correlated with the fracture morphology of all the vulcanizates. The tensile rupture of NaMAA‐filled EVM vulcanizates occurred through tearing from a crack in the bulk of the samples. Tear deviation occurred with the addition of NaMAA and resulted in a rough surface, leading to an improvement in the tear strength of NaMAA‐filled EVM vulcanizates. The micrographs of the tear surfaces of the vulcanizates indicated that the different fracture modes depended on the NaMAA loading and the crosslink density. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1715–1724, 2004
Fracture toughness of nylon‐6 blends with maleated rubbers
Authors: Okada O. , Keskkula H. , Paul D. R.
Published: March 2004

The fracture toughness of blends of nylon‐6 with maleated ethylene–propylene rubber and maleated styrene/hydrogenated butadiene/styrene triblock copolymer was investigated with a single‐edge‐notched three‐point‐bending instrumented Dynatup test. The blends for which the rubber particle size was less than 0.7 μm fractured in a ductile manner over the whole range of ligament lengths, whereas the blends with particles larger than 0.7 μm showed a ductile‐to‐brittle transition with the ligament length. In this regime, ductile fracture was observed for specimens with short ligaments, whereas brittle fracture was seen for those with long ligaments. The ductile fracture behavior was analyzed with the essential‐work‐of‐fracture model, whereas linear elastic fracture mechanics techniques were used to analyze the brittle fracture behavior. The fact that the ductile fracture energy was larger for the blends with the styrene/hydrogenated butadiene/styrene triblock copolymer than for those with ethylene–propylene rubber was due to the larger dissipative energy density of the blends based on the styrene/hydrogenated butadiene/styrene triblock copolymer. Both the critical strain energy release rate (GIC) and the plane‐strain critical stress intensity factor (KIC) increased as the rubber particle size decreased for both blend systems. The GIC and KIC parameters had similar values, regardless of the rubber type, when the rubber particle size was fixed. The transition ligament length was near the size criterion for plane‐strain conditions for both blend systems. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1739–1758, 2004
Improving the effectiveness of adjuvant psychological treatment for women with breast cancer: The feasibility of providing online support
Authors: Owen Jason E. , Klapow Joshua C. , Roth David L. , Nabell Lisle , Tucker Diane C.
Published: March 2004

Many well‐designed studies have shown psychosocial treatments for cancer to be efficacious for improving patients' quality of life, but the actual impact of these treatments may be limited by low rates of participation. Web‐based treatment formats could improve effectiveness by increasing availability and accessibility. Two phases of a feasibility study are reported in this article. In the first phase, we sought to assess internet access and perceived interest in online support among 136 women with breast cancer (June–October, 1999). Levels of interest in participating in an online psychosocial treatment were associated with age, outcome expectancy, and barriers to using the internet but not stage or time since diagnosis. In the second phase, we document accrual rates among several methods of recruitment during a randomized trial (February–December, 2001) and report changes over time in internet access. Recruitment rates were substantially higher when a study representative was available in clinic to provide information about the treatment than for all other methods of recruitment. Access to the internet increased between 1999 (63%) and 2001 (70%) and varied across age groups. These results suggest that internet‐based psychosocial treatments, with notable limitations, are feasible for increasing the impact of psychosocial care. Copyright © 2003 John Wiley & Sons, Ltd.
Screening for depression in head and neck cancer
Authors: Katz Mark R. , Kopek Neil , Waldron John , Devins Gerald M. , Tomlinson George
Published: March 2004

Objectives: The objectives of this study are to identify the prevalence of depression and the accuracy of depression screening instruments in ambulatory head and neck cancer patients who have received radiation. This population is at risk for depression because of the life‐threatening nature of the illness, and treatment‐induced oral morbidity.

Methods: Sixty subjects were evaluated for Major and Minor Depression according to Research Diagnostic Criteria using the Schedule for Affective Disorders and Schizophrenia (SADS). Screening instruments examined were the Beck Depression Inventory (BDI), the Hospital Anxiety and Depression Scale (HADS) and the Centre for Epidemiological Studies‐Depression (CES‐D) scale. Accuracy was assessed by calculating the sensitivities, specificities, positive predictive values (PPV) and areas under curve (AUC) from Receiver Operating Characteristic (ROC) curves.

Results: The prevalence of Major and Minor Depression was 20%. All of the screening instruments tested were found to be highly accurate. Statistically significant differences between the instruments were not observed but the HADS demonstrated the highest absolute levels of sensitivity, specificity and PPV. No cases of Major Depression were missed by any of the instruments tested.

Conclusions: These results suggest that a significant minority of head and neck cancer patients are depressed in the post radiation period, and that accurate screening for clinically significant depression is possible using any of the three instruments evaluated here. Copyright © 2003 John Wiley & Sons, Ltd.
Correlates of posttraumatic growth in husbands of breast cancer survivors
Authors: Weiss Tzipi
Published: March 2004

Following breast cancer, many survivors and spouses report posttraumatic growth (PTG)—positive life changes. This correlational study identified social context and event‐related correlates of PTG among husbands of breast cancer survivors (N=72). Bivariate analyses indicated that husbands' PTG was positively associated with general social support, greater marital support and depth of commitment, greater PTG in wife, shorter time since diagnosis and breast cancer meeting DSM‐IV criteria for traumatic stressor. Multiple regression analysis revealed that the significant predictors of husbands' PTG were depth of marital commitment, wife's PTG, and breast cancer meeting DSM‐IV traumatic stressor criteria. Psychosocial research and interventions need to acknowledge that couples face the cancer together and share not only the pain but also the potential for gain from the trauma. Copyright © 2003 John Wiley & Sons, Ltd.
The impact of an informational self‐management intervention on the association between control and illness uncertainty before and psychological distress after radiotherapy
Authors: Stiegelis Heidi E. , Hagedoorn Mariët , Sanderman Robbert , Bennenbroek Femke T.C. , Buunk Bram P. , Bergh Alfons C.M. van den , Botke Gerrit , Ranchor Adelita V.
Published: March 2004

Many studies have reported that cancer patients who show difficulties maintaining perceptions of control report more psychological distress than patients who are higher in control. Besides perceptions of control, feelings of illness uncertainty have also been regarded as a predictor of psychological distress. Given these strong relationships between perceptions of low control and high illness uncertainty and psychological distress, the present study examined whether an informational self‐management intervention (booklet) could moderate this relationship. The booklet contained general and specific information about cancer and cancer treatment, information about possible coping strategies, and social comparison information, which consisted of short stories of other patients. Prior to radiotherapy, 209 patients with cancer completed baseline measures, including control and illness uncertainty. After completing radiotherapy, patients were randomly allocated to receive either a booklet (experimental group; N=103) or no booklet (control group; N=106). Three months after the intervention, aspects of psychological distress were assessed, including tension, anger, depression, fatigue and vigour. The results supported our hypotheses and suggested that a self‐management intervention is relevant in reducing the relationship between control and illness uncertainty before radiotherapy and psychological distress after radiotherapy. This seems important, especially for high‐risk patients who perceive little control and much illness uncertainty. Copyright © 2003 John Wiley & Sons, Ltd.
The vertex degree distribution of random intersection graphs
Authors: Stark Dudley
Published: March 2004

Random intersection graphs are a model of random graphs in which each vertex is assigned a subset of a set of objects independently and two vertices are adjacent if their assigned subsets are not disjoint. The number of vertices is denoted by n and the number of objects is supposed to be ⌊nα⌋ for some α > 0. We determine the distribution of the degree of a typical vertex and show that it changes sharply between α > 1, α = 1, and α > 1. © 2004 Wiley Periodicals, Inc. Random Struct. Alg., 2004