bluuebunny/crossref_metadata_2025_split huggingface dataset:
Moment and direction of the spoiler gradient for effective artifact suppression in RF‐spoiled gradient echo imaging
Authors: Leupold Jochen , Hennig Jürgen , Scheffler Klaus 
Published: June 2008

AbstractRadiofrequency (RF) ‐spoiled gradient echo sequences were developed with the aim to produce images with T1weighted contrast within short acquisition time. Over the past two decades, this type of sequence has proven to be a robust technique and represents a reliable workhorse in clinical MRI. This study presents an analysis of ghost artifacts, which appear occasionally in RF‐spoiled gradient echo images. It is demonstrated that the artifacts result from intrinsically emerging signal oscillations, which can be damped down by the application of spoiler gradients. Magn Reson Med 60:119–127, 2008. © 2008 Wiley‐Liss, Inc.
Circumferential strain in the wall of the common carotid artery: Comparing displacement‐encoded and cine MRI in volunteers
Authors: Lin Alexander P. , Bennett Eric , Wisk Lauren E. , Gharib Morteza , Fraser Scott E. , Wen Han 
Published: June 2008

AbstractThe walls of conduit arteries undergo cyclic stretching from the periodic fluctuation of arterial pressure. Atherosclerotic lesions have been shown to localize to regions of excessive stretching of the arterial wall. We employed a displacement encoding with stimulated echoes (DENSE) sequence to image the motion of the common carotid artery wall and map the two‐dimensional (2D) circumferential strain. The sequence utilizes a fully‐balanced steady‐state free‐precession (SSFP) readout with 0.60 mm in‐plane resolution. Preliminary results in volunteers at 1.5T (N = 4) and 3.0T (N = 17) are compared to measurements of the lumen circumference from cine images. The agreement between the two independent measurements at both field strengths (P ≤ 0.001) supports the use of DENSE as a means to map the pulsatile strain in the carotid artery wall. Magn Reson Med 60:8–13, 2008. © 2008 Wiley‐Liss, Inc.
Contrast‐enhanced magnetic resonance angiography in peripheral arterial disease: Improving image quality by automated image registration
Authors: Menke Jan 
Published: June 2008

AbstractIn peripheral arterial disease, contrast‐enhanced MR angiography (MRA) is a noninvasive imaging alternative for catheter‐based digital subtraction angiography (DSA). In DSA, final images are generated by subtracting a native mask image from subsequent contrast‐enhanced images. Image quality is routinely improved by digitally shifting the mask image prior to subtraction if the patient has moved during angiography. This study investigated whether such image registration may also help to improve the image quality of MRA. In all, 545 MRA examinations of pelvic and leg arteries in patients with symptoms of peripheral arterial disease were studied retrospectively. Standard nonregistered MRA was compared to automatically linear, affine, and warp registered MRA by visual analysis and by three image quality parameters, including vessel detection probability (VDP) of angiographic maximum intensity projections. Most MRA of pelvic and upper leg arteries showed good nonregistered image quality. However, the 15% of lower legs with a body shift of 1 mm or more had relatively low nonregistered image quality, which improved significantly with image registration (VDP gain more than 18%, P < 0.05). The visual analysis gave similar results. In conclusion, image registration can improve image quality of MRA in peripheral arterial disease, especially in the lower legs. Magn Reson Med 60:224–229, 2008. © 2008 Wiley‐Liss, Inc.
Visualizing water clearance in the lung with MRI
Authors: Vidarsson Logi , Helm Emma , O'Brodovich Hugh , Macgowan Christopher K. 
Published: June 2008

AbstractCurrent indirect measurements of alveolar fluid clearance (AFC) suggest that the rate of fluid clearance correlates with morbidity and mortality in patients with pulmonary edema. In a traditional AFC‐measurement, fluid laced with a tracer macromolecule is instilled into the lung and thereafter repeated samples of the instilled fluid are extracted from the lung's fluid‐filled airspaces. The change in concentration of the tracer molecule indicates the AFC‐rate. In this work, a new MRI technique was developed to image lung water clearance by adding Gadolinium‐DTPA to the instilled fluid. As fluid is absorbed by the animal, the concentration of gadolinium will increase, reducing the T1 relaxation time. By repeatedly measuring the T1 relaxation time, the AFC can be tracked over time with high spatial resolution. The new technique was tested both in phantoms and 10 Yorkshire piglets. Magn Reson Med 60:230–235, 2008. © 2008 Wiley‐Liss, Inc.
Assessing transneuronal dysfunction utilizing manganese‐enhanced MRI (MEMRI)
Authors: Serrano Faridis , Deshazer Mitchell , Smith Karen D.B. , Ananta Jeyarama S. , Wilson Lon J. , Pautler Robia G. 
Published: June 2008

AbstractIn this study we utilized manganese‐enhanced MRI (MEMRI) to evaluate the in vivo transneuronal efficiency of manganese ion (Mn2+) movement as a means to assess overall changes in neuronal function. We designated this extension the manganese transfer index (MTI) value. To evaluate the MTI value as an index of transneuronal physiology we examined both pharmacological agents and different mouse models of neuronal dysfunction. We found that treatment with isoflurane, which attenuates synaptic vesicle release, or memantine, which attenuates postsynaptic uptake of Ca2+ as well as Mn2+, resulted in a decrease in the MTI value. Furthermore, we evaluated if changes in the MTI value can be detected in three knockout mice with altered brain function accompanied either with or without neurodegeneration. Our data demonstrate that the MTI values either decreased or increased in response to different functional as well as anatomical changes. These results demonstrate the potential utility of the MTI value as an in vivo index for the detection of changes in neuronal function in animal models of human disease. Magn Reson Med 60:169–175, 2008. © 2008 Wiley‐Liss, Inc.
Flavonoid glucuronides with anti‐leukaemic activity from Polygonum amphibium L.
Authors: Smolarz H. D. , Budzianowski J. , Bogucka‐Kocka A. , Kocki J. , Mendyk E. 
Published: June 2008

AbstractIntroduction – The chemical and pharmaceutical studies carried out on species from Polygonum L. genus showed biological activity both of the extracts and the components isolated from them. These results were the impulse to examine Polygonum amphibium L.Objective – The aim of this study was the isolation of active components from methanol extract and the determination of their cytotoxic effect on human leukaemic cell lines.Methodology – Three flavonoid components from butanol soluble fractions of methanol extract by CC and PC preparative chromatography were isolated. Their structures were established on the basis of 1H, 13C and correlation (DEPT, H‐H, COSY, HMQC, HMBC) NMR, UV and FAB‐MS spectroscopic techniques. The evaluation of the anti‐leukaemic activities of 1 and 2 against Jurkat and HL60 cell lines was carried out in vitro using annexin V fluorescence assay.Results – Two new flavonoid glucuronides, quercetin‐3‐O‐β‐glucuronide (1) and quercetin‐3‐O‐α‐rhamnosyl‐(1 → 2)‐β‐glucuronide (2), and kaempferol‐3‐O‐α‐rhamnosyl‐(1 → 2)‐β‐glucuronide (3), were isolated from Polygonum amphibium L. It was demonstrated that the glucuronides of quercetin are able to induce apoptosis in the tested human leukaemic cells. These compounds penetrate through cytoplasm to the cellular nucleus of the cultured cells, and give intensive apoptotic responses in the stimulated leukaemic cells. The number of apoptotic cells increased with the concentration (1 nm to 10 µm) of 1 or 2 and periods of exposure (1–3 days).Conclusion – Compounds 1 and 2 may be considered good candidates for leukaemia chemotherapeutic agents. Copyright © 2008 John Wiley & Sons, Ltd.
Thermomechanical analysis and modeling of the extrusion coating process
Authors: Sollogoub C. , Felder E. , Demay Y. , Agassant J.F. , Deparis P. , Mikler N. 
Published: June 2008

AbstractDuring the extrusion coating process, a polymer film is extruded through a flat die, stretched in air, and then coated on a substrate (steel sheet in our case) in a laminator consisting of a chill roll and a flexible pressure roll. The nip, i.e. the area formed by the contact between the pressure and the chill rolls, constitutes the heart of the extrusion coating process. Indeed, in this region, some of the most critical properties, such as adhesion, barrier properties, optical properties, are achieved or lost. In this article, we first present an experimental investigation of the coating step, which enables to characterize the leading thermomechanical phenomena. It is shown that there is no polymer macroscopic flow in the nip, but a local flow within the asperities of the steel substrate surface. This microscopic flow, at the interface between the film and the substrate, is slowed by strong cooling conditions in the nip. Several models are then proposed, giving access to the temperature profile through polymer thickness and substrate, the pressure distribution in the nip as well as the behavior of the polymer melt in the nip at the interface with the substrate. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Valorization of poly(butylene terephthalate) wastes by blending with virgin polypropylene: Effect of the composition and the compatibilization
Authors: Barhoumi Najoua , Jaziri Mohamed , Massardier Valérie , Cassagnau Philippe 
Published: June 2008

AbstractBlends of recycled poly(butylene terephthalate) (PBT) parts obtained from scrapped cars, and virgin polypropylene (PP), were prepared in a twin‐screw extruder at different compositions. Selected compositions were also prepared with the presence of ethylene‐co‐glycidyl methacrylate copolymer (E‐GMA) and ethylene/methyl acrylate/glycidyl methacrylate terpolymer (E‐MA‐GMA) compatibilizers. The effect of the composition and the type of compatibilizer, as well as the mixing conditions, on the morphology phase, thermal, viscoelastic behavior, and mechanical properties of the blends has been investigated. Blends PP/PBT of various composition exhibit a coarse morphology and a poor adherence between both phases, resulting in the decrease of ductility, whereas at weak deformation, PBT reinforced the tensile properties of PP. Addition of E‐GMA and E‐MA‐GMA to the PP/PBT blend exhibited a significant change in morphology and improved ductility because of interfacial reactions between PBT end chains and epoxy groups of GMA that generate EG‐g‐PBT copolymer. Moreover, thermal and viscoelastic study indicated that the miscibility of PP and PBT has been improved further and the reactions were identified. The E‐MA‐GMA results in the best improvement of ductility. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Photooxidative behavior of polystyrene–montmorillonite nanocomposites
Authors: Oliveira C.F.P. , Carastan D.J. , Demarquette N.R. , Fechine G.J.M. 
Published: June 2008

AbstractThe weathering behavior of polystyrene and polystyrene–montmorillonite composites containing 2.5, 5.0, and 7.5 wt% of montmorillonite (MMT) was investigated. Samples were exposed to UV radiation for periods of up to ∼12 weeks and their molecular weight, chemical changes, and mechanical properties were monitored as a function of time. The addition of MMT was shown to improve the photostability of all composites investigated, probably because of a screen effect against UV radiation and barrier effect against diffusion of oxygen promoted by the silicate layers of MMT. Scanning electron microscopy of fracture surfaces of degraded samples showed that there is a degraded layer near the surface that provided a recovery of tensile strength of the samples. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Effects of initiator type in rigid polyurethane foams
Authors: Kim Sung Hee , Lim Ho , Kim Byung Kyu 
Published: June 2008

AbstractRigid polyurethane foams (RPUFs) have been synthesized from high‐functional polymeric 4,4′‐diphenylmethane diisocyanate (PMDI) and polypropylene glycols (PPG), which were prepared from sorbitol and its combinations with toluene diamine (TDA, T), ethylene diamine (EDA, E), and sucrose/glycerin (G) using environmentally friendly blowing agent, i.e., HFC 365mfc and/or distilled water. Effects of initiator type and blowing agent content have been analyzed in terms of cell morphology, thermal conductivity, and mechanical and dynamic mechanical properties. It was found that TDA‐based initiators gave smallest cell, highest value of rubbery plateau modulus, and greatest thermal insulation, whereas EDA gave the greatest dimensional stability. It was also found that the foam properties were largely governed by the blowing agent, whereas initiator gave fine controls of the properties. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Detecting crystallization structure evolution of polypropylene injection‐molded bar induced by nucleating agent
Authors: Bai Hongwei , Wang Yong , Song Bo , Li Yanli , Liu Li 
Published: June 2008

AbstractThe crystallization structures of Polypropylene (PP) injection‐molded bars nucleated by nucleating agent were detected from the skin layer to the core zone, layer by layer. α‐phase nucleating agent 1,3:2,4‐bis (3,4‐dimethylbenzylidene) sorbitol (DMDBS, Millad 3988), β‐phase nucleating agent aryl amides compounds (TMB‐5), and their compounds were introduced into PP matrix, respectively. The relative content of β‐phase PP in the different zones of an injection‐molded bar was characterized and calculated by Wide angle X‐ray diffraction (WAXD) and Differential scanning calorimetry (DSC). The results show that, whether in pure PP or in nucleated PP, both β‐phase PP and α‐phase PP grow in the skin layer of the injection‐molded bar. However, in the intermediate layers and the core zone, the crystallization structures of PP are dependent on the used nucleating agent. β‐phase is the main crystallization structure of TMB‐5 (0.1 and 0.2 wt%) nucleated PP, and α‐phase in DMDBS (0.1 and 0.2 wt%) nucleated PP. Compounding nucleating agents with 0.1 wt% DMDBS and 0.1 wt% TMB‐5 induces PP crystallization almost in β‐phase; however, PP nucleated by 0.2 wt% DMDBS and 0.2 wt% TMB‐5 crystallizes exclusively in α‐phase. The crystallization mechanism of PP nucleated by compounding nucleating agents was further studied in this work. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Numerical and experimental investigation of shrinkage behavior of precision injection molded articles. II. Results and discussion
Authors: Yang Sang Sik , Kwon Tai Hun 
Published: June 2008

AbstractIn the accompanying paper, Part I, presented are the physical modeling and numerical formulation of new lateral motion modelings. In Part II, new models developed in Part I are validated by the successful comparison of calculated residual stress profile with the literature data. The predicted results of the birefringence, residual stress distribution, and shrinkage from new lateral motion modeling are in better agreement with corresponding experimental data than those from the conventional ones. The new model prediction falls between those of two extreme cases corresponding to conventional models. As a result of extensive parametric study of processing conditions, the developed analysis system is found to be capable of successfully predicting the tendency of shrinkage behavior varying with most of processing conditions. In this regard, the new model enables better analysis based design and optimization of precision injection‐molded products. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Unusual thermal degradation of maleic anhydride grafted polyethylene
Authors: Huang Jiann‐Wen , Lu Wei‐Chieh , Yeh Mou‐Yu , Lin Chih‐Hsiang , Tsai I‐Shou 
Published: June 2008

AbstractThermal degradation of maleic anhydride grafted polyethylene (manPE) in nitrogen and in air was studied by thermogravimetry and differential scanning calorimetry. The decomposition temperature of manPE in nitrogen shifted to a higher value with increasing heating rate, but a complex thermal phenomenon was observed when manPE decomposed in air. Chain scission and crosslinking are proposed as two counteractive factors to determine the decomposition temperature in air. Radical species (R•) and hydroxyl groups (ROH) form when manPE degraded in air. The radical species accelerate the oxidative degradation, but ROH could react with the maleic anhydride groups to form a stable crosslinking structure. Both slow heating and prolong heating at 220°C allow the stabilizing reaction to proceed to a higher degree between ROH and the maleic anhydride groups and lead to enhanced thermal stability of manPE. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Numerical and experimental investigation of shrinkage behavior of precision injection molded articles. I. Development of lateral motion modeling
Authors: Yang Sang Sik , Kwon Tai Hun 
Published: June 2008

AbstractThe present study aims at improving the state of art physical modeling in the numerical simulation for a precision injection molding to take into account the shrinkage behavior observed by experimental measurements. In Part I, new lateral motion models have been developed to predict the birefringence, residual stress profiles, and effects of various processing conditions on the shrinkage altogether. In conventional models, the lateral motion is either allowed too early or totally prohibited in the cooling stage. With the new modeling, more general description of lateral motion has been achieved either by allowing the lateral motion if an averaged lateral residual stress reaches a certain value or by letting the lateral motion develop continuously when a shearing strength is equal to an estimated shear stress. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Luminance of injection‐molded V‐groove light guide plates
Authors: Lin T.H. , Isayev A.I. , Mehranpour M. 
Published: June 2008

AbstractInjection‐molded V‐groove light‐guide plates (LGPs) were made of two optical grade polycarbonates of different viscosities at various molding conditions. Their luminance as a function of viewing angle was measured. The depth of melt filling of the grooves in LGPs was measured at different locations selected based on the melt front propagation during the cavity filling. The depth of melt filling of grooves was mostly completed during the cavity‐filling stage. It was only slightly affected by the packing pressure and packing time and strongly affected by other molding conditions and layout of the V‐grooves. Luminance of LGPs showed a strong correlation with the depth of melt filling of the V‐grooves. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
New aramid‐based nanocomposites: Synthesis and characterization
Authors: Zulfiqar Sonia , Lieberwirth Ingo , Ahmad Zahoor , Sarwar Muhammad Ilyas 
Published: June 2008

AbstractNew type of nanocomposites containing various proportions of montmorillonite in aromatic polyamide was prepared via solution intercalation method. Aramid chains were synthesized by reacting 4,4′‐oxydianiline with isophthaloyl chloride in N,N′‐dimethyl acetamide. Dodecylamine was used as swelling agent to change the hydrophilic nature of montmorillonite into organophilic. Appropriate amounts of organoclay were mixed in the polymer solution using high‐speed mixer for complete dispersion of the clay. Thin films cast from these materials after evaporating the solvent were characterized by XRD, TEM, mechanical, thermal, and water absorption measurements. The structure and morphology of the nanocomposites determined by XRD and TEM revealed the formation of exfoliated and intercalated clay platelets in the aramid matrix. Mechanical data indicated improvement in the tensile strength and modulus of the nanocomposites with clay loading up to 6 wt%. The glass transition temperature increased up to 12 wt% clay content and thermal stability amplified with increasing clay loading. The water absorption reduced gradually as a function of organoclay and approached to zero with 20 wt% organoclay in the aramid. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Electronic structure evidence for all‐trans poly(methylvinylidene cyanide)
Authors: Xiao Jie , Poulsen Matt , Reddy D. Sahadeva , Takacs J.M. , Losovyj Y.B. , Dowben P.A. 
Published: June 2008

AbstractOn the basis of a comparison of theoretical quantum calculations, by both semiempirical and ab initio methods, with photoemission and inverse photoemission results, we suggest that polymethylvinylidenecyanide (PMVC) adopts an all‐trans conformation with few, if any, alternating trans‐gauche carbon–carbon bond arrangements. The comparison of theory with the available photoemission and inverse photoemission excludes the presence of a significant fraction of gauche bonds in the polymer chains, indicative of the all‐trans conformation, with dipoles all aligned. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Temperature‐dependent deformation and damage behaviour of ultrafine‐grained copper under uniaxial compression
Authors: Yu Zhao‐Yuan , Jiang Qing‐Wei , Li Xiao‐Wu 
Published: June 2008

AbstractThe plastic deformation and damage behaviour of ultrafine‐grained (UFG) copper produced by equal channel angular pressing were investigated at temperatures ranging from room temperature to 573 K under uniaxial compression. It was found that the testing temperature has a strong effect on the corresponding mechanical behaviour of UFG copper. For example, the compressive yield stress and steady flow stress of UFG copper decease generally with increasing temperature. In the case of temperatures below recrystallization, an enhanced early‐stage strain softening was observed with increasing temperature. Compressive deformation damage features of UFG copper are also strongly dependent on the temperature. Small‐ and large‐scale cracks were observed to form along the shear bands at room temperature, whereas microvoids or cracks were found to nucleate at grain boundaries at temperatures above recrystallization. At in‐between temperatures, some microvoids with various sizes were detected along the shear direction. Such temperature‐dependent deformation and damage behavior are closely related with the corresponding microstructural changes after compressive deformation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Directed Aerosol Writing of Ordered Silica Nanostructures on Arbitrary Surfaces with Self‐Assembling Inks
Authors: Pang Jiebin , Stuecker John N. , Jiang Yingbing , Bhakta Ajay J. , Branson Eric D. , Li Peng , Cesarano Joseph , Sutton David , Calvert Paul , Brinker C. Jeffrey 
Published: June 2008

AbstractThis paper reports the fabrication of micro‐ and macropatterns of ordered mesostructured silica on arbitrary flat and curved surfaces using a facile robot‐directed aerosol printing process. Starting with a homogenous solution of soluble silica, ethanol, water, and surfactant as a self‐assembling ink, a columnated stream of aerosol droplets is directed to the substrate surface. For deposition at room temperature droplet coalescence on the substrates and attendant solvent evaporation result in continuous, highly ordered mesophases. The pattern profiles are varied by changing any number of printing parameters such as material deposition rate, printing speed, and aerosol‐head temperature. Increasing the aerosol temperature results in a decrease of the mesostructure ordering, since faster solvent evaporation and enhanced silica condensation at higher temperatures kinetically impede the molecular assembly process. This facile technique provides powerful control of the printed materials at both the nanoscale and microscale through chemical self‐assembly and robotic engineering, respectively.