bluuebunny/crossref_metadata_2025_split huggingface dataset:
MRI of the basement membrane using charged nanoparticles as contrast agents
Authors: Bennett Kevin M. , Zhou Hua , Sumner James P. , Dodd Stephen J. , Bouraoud Nadia , Doi Kent , Star Robert A. , Koretsky Alan P. 
Published: August 2008

AbstractThe integrity of the basement membrane is essential for tissue cellular growth and is often altered in disease. In this work a method for noninvasively detecting the structural integrity of the basement membrane, based on the delivery of cationic iron‐oxide nanoparticles, was developed. Cationic particles accumulate due to the highly negative charge of proteoglycans in the basement membrane. The kidney was used to test this technique because of its highly fenestrated endothelia and well‐established disease models to manipulate the basement membrane charge barrier. After systemic injection of cationic or native ferritin (CF or NF) in rats, ex vivo and in vivo MRI showed selective accumulation of CF, but not NF, causing a 60% reduction in signal intensity in cortex at the location of individual glomeruli. Immunofluorescence and electron microscopy demonstrated that this CF accumulation was localized to the glomerular basement membrane (GBM). In a model of GBM breakdown during focal and segmental glomerulosclerosis, MRI showed reduced single glomerular accumulation of CF, but a diffuse accumulation of CF in the kidney tubules caused by leakage of CF through the glomerulus. Cationic contrast agents can be used to target the basement membrane and detect the breakdown of the basement membrane in disease. Magn Reson Med 60:564–574, 2008. © 2008 Wiley‐Liss, Inc.
Fat‐water separated delayed hyperenhanced myocardial infarct imaging
Authors: Goldfarb James W. 
Published: August 2008

AbstractFat deposition associated with myocardial infarction (MI) has been reported as a commonly occurring phenomenon. Magnetic resonance imaging (MRI) has the ability to efficiently detect MI using T1‐sensitive contrast‐enhanced sequences and fat via its resonant frequency shift. In this work, the feasibility of fat‐water separation applied to the conventional delayed hyperenhanced (DHE) MI imaging technique is demonstrated. A three‐point Dixon acquisition and reconstruction was combined with an inversion recovery gradient‐echo pulse sequence. This allowed fat‐water separation along with T1 sensitive imaging after injection of a gadolinium contrast agent. The technique is demonstrated in phantom experiments and three subjects with chronic MI. Areas of infarction were well defined as conventional hyperenhancement in water images. In two cases, fatty deposition was detected in fat images and confirmed by precontrast opposed‐phase imaging. Magn Reson Med 60:503–509, 2008. © 2008 Wiley‐Liss, Inc.
Positive contrast visualization of nitinol devices using susceptibility gradient mapping
Authors: Vonken Evert‐jan P.A. , Schär Michael , Stuber Matthias 
Published: August 2008

AbstractMRI visualization of devices is traditionally based on signal loss due toT2* effects originating from local susceptibility differences. To visualize nitinol devices with positive contrast, a recently introduced postprocessing method is adapted to map the induced susceptibility gradients. This method operates on regular gradient‐echo MR images and maps the shift ink‐space in a (small) neighborhood of every voxel by Fourier analysis followed by a center‐of‐mass calculation. The quantitative map of the local shifts generates the positive contrast image of the devices, while areas without susceptibility gradients render a background with noise only. The positive signal response of this method depends only on the choice of the voxel neighborhood size. The properties of the method are explained and the visualizations of a nitinol wire and two stents are shown for illustration. Magn Reson Med 60:588–594, 2008. © 2008 Wiley‐Liss, Inc.
In vivo 1H NMR measurement of glycine in rat brain at 9.4 T at short echo time
Authors: Gambarota Giulio , Xin Lijing , Perazzolo Chiara , Kohler Ingrid , Mlynárik Vladimír , Gruetter Rolf 
Published: August 2008

AbstractGlycine is an amino acid present in mammalian brain, where it acts as an inhibitory and excitatory neurotransmitter. The two detectable protons of glycine give rise to a singlet at 3.55 ppm that overlaps with the more intense myo‐inositol resonances, and its measurement has traditionally required specific editing efforts. The aim of the current study was to reduce the signal intensity of myo‐inositol relative to that of glycine by exploiting the fast signal J‐evolution of the myo‐inositol spin system when using a single spin‐echo localization method we recently introduced. Glycine was detected at TE = 20 ms with an average Cramér‐Rao lower bound (CRLB) of 8.6% ± 1.5% in rat brain (N = 5), at 9.4 T. The concentration of glycine was determined using LCModel analysis at 1.1 ± 0.1 mM, in good agreement with biochemical measurements previously reported. We conclude that at high magnetic fields, glycine can be measured at a relatively short echo time (TE) without additional editing efforts. Magn Reson Med 60:727–731, 2008. © 2008 Wiley‐Liss, Inc.
Prospective self‐gating for simultaneous compensation of cardiac and respiratory motion
Authors: Buehrer Martin , Curcic Jelena , Boesiger Peter , Kozerke Sebastian 
Published: August 2008

AbstractSegmented cardiac acquisitions generally require the use of an electrocardiogram (ECG) in combination with a breathhold or a respiratory navigator placed on the diaphragm. These techniques necessitate patient cooperation and increase the complexity of cardiac imaging. The ECG signal may be distorted inside the magnet by interferences from radiofrequency and gradient action. Breathhold acquisition limits the total scan time, while navigators on the diaphragm might not fully reflect respiratory‐induced motion of the heart. To overcome some of these problems, several self‐gating (SG) or “wireless” techniques have recently been presented. All of these approaches, however, are based on either cardiac triggering or respiratory gating, or the data are processed retrospectively, reducing the efficiency of data acquisition. In this work a prospective SG approach for free‐breathing imaging is presented that requires neither ECG gating nor respiratory navigation. The motion data used for cardiac triggering and respiratory gating are extracted from the repeatedly acquired k‐space center. Based on computer simulations and in vivo data of the heart, it is shown that cardiac as well as respiratory motion can be accurately extracted in real time. Using the method proposed, the scan efficiency could be significantly increased while preserving image quality relative to retrospective SG approaches. Magn Reson Med 60:683–690, 2008. © 2008 Wiley‐Liss, Inc.
Reproducibility study of whole‐brain 1H spectroscopic imaging with automated quantification
Authors: Gu Meng , Kim Dong‐Hyun , Mayer Dirk , Sullivan Edith V. , Pfefferbaum Adolf , Spielman Daniel M. 
Published: August 2008

AbstractA reproducibility study of proton MR spectroscopic imaging (1H‐MRSI) of the human brain was conducted to evaluate the reliability of an automated 3D in vivo spectroscopic imaging acquisition and associated quantification algorithm. A PRESS‐based pulse sequence was implemented using dualband spectral‐spatial RF pulses designed to fully excite the singlet resonances of choline (Cho), creatine (Cre), and N‐acetyl aspartate (NAA) while simultaneously suppressing water and lipids; 1% of the water signal was left to be used as a reference signal for robust data processing, and additional lipid suppression was obtained using adiabatic inversion recovery. Spiral k‐space trajectories were used for fast spectral and spatial encoding yielding high‐quality spectra from 1 cc voxels throughout the brain with a 13‐min acquisition time. Data were acquired with an 8‐channel phased‐array coil and optimal signal‐to‐noise ratio (SNR) for the combined signals was achieved using a weighting based on the residual water signal. Automated quantification of the spectrum of each voxel was performed using LCModel. The complete study consisted of eight healthy adult subjects to assess intersubject variations and two subjects scanned six times each to assess intrasubject variations. The results demonstrate that reproducible whole‐brain 1H‐MRSI data can be robustly obtained with the proposed methods. Magn Reson Med 60:542–547, 2008. © 2008 Wiley‐Liss, Inc.
Multiple‐profile homogeneous image combination: Application to phase‐cycled SSFP and multicoil imaging
Authors: Çukur Tolga , Lustig Michael , Nishimura Dwight G. 
Published: August 2008

AbstractSignal inhomogeneities in MRI often appear as multiplicative weightings due to various factors such as field‐inhomogeneity dependencies for steady‐state free precession (SSFP) imaging or receiver sensitivities for coil arrays. These signal inhomogeneities can be reduced by combining multiple data sets with different weights. A sum‐of‐squares combination is typically used due to its simplicity and near‐optimal signal‐to‐noise ratio (SNR). However, this combination may lead to residual signal inhomogeneity. Alternatively, an optimal linear combination of the data can be performed if the weightings for individual data sets are estimated accurately. We propose a nonlinear combination to improve image‐based estimates of the individual weightings. The signal homogeneity can be significantly increased without compromising SNR. The improved performance of the method is demonstrated for SSFP banding artifact reduction and multicoil (phased‐array and parallel) image reconstructions. Magn Reson Med 60:732–738, 2008. © 2008 Wiley‐Liss, Inc.
Domain decomposition of stochastic PDEs: Theoretical formulations
Authors: Sarkar Abhijit , Benabbou Nabil , Ghanem Roger 
Published: August 2008

AbstractWe present a novel theoretical framework for the domain decomposition of uncertain systems defined by stochastic partial differential equations. The methodology involves a domain decomposition method in the geometric space and a functional decomposition in the probabilistic space. The probabilistic decomposition is based on a version of stochastic finite elements based on orthogonal decompositions and projections of stochastic processes. The spatial decomposition is achieved through a Schur‐complement‐based domain decomposition. The methodology aims to exploit the full potential of high‐performance computing platforms by reducing discretization errors with high‐resolution numerical model in conjunction to giving due regards to uncertainty in the system. The mathematical formulation is numerically validated with an example of waves in random media. Copyright © 2008 John Wiley & Sons, Ltd.
Medizinische Chemie und molekulare Hemmmechanismen der Tyrosinkinase‐Inhibitoren. Schwerpunkt pharmazeutischer Forschung
Authors: Holm Melanie , Lehmann Frank , Laufer Stefan 
Published: August 2008

AbstractDie meisten Prozesse einer Zelle werden durch Proteinphosphorylierungen reguliert, wohingegen anormale Phosphorylierung ein Grund für oder eine Konsequenz von Krankheiten ist. Ein stetig steigendes Interesse an der Entwicklung von oral applizierbaren, aktiven Proteinkinase‐Hemmstoffen hat mittlerweile zur Zulassung der ersten Wirkstoffe geführt. Proteinkinasen sind inzwischen die zweitwichtigste Gruppe der Wirkstoff‐Targets nach den G‐Protein‐gekoppelten Rezeptoren. Nach Schätzungen zielen heutzutage 30 bis 35 % aller präklinischen Wirkstofffindungsprogramme auf Proteinkinasen ab.
Compressive strength of gamma‐irradiated polymer concrete
Authors: Martínez‐Barrera Gonzalo , Villarruel Uriel Texcalpa , Vigueras‐Santiago Enrique , Hernández‐López Susana , Brostow Witold 
Published: August 2008

AbstractPolymer concrete (PC) was developed by using different concentrations of silica sand as aggregate and a commercial unsaturated preaccelerated (orthophtalic) polyester resin. The PC specimens were submitted to gamma radiation at several dosages: 5, 10, 50, 100, and 150 kGy. Mechanical performance was evaluated including the compressive strength, the compressive strain at yield point, and the compression modulus of elasticity. As expected, mechanical properties depend on both the resin concentration and the applied radiation dose. Improvement achieved in mechanical properties is related to the morphological characteristics observed by scanning electron microscopy. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers
Influence of erodent particle types on solid particle erosion of polyphenylene sulphide composite under low particle speed
Authors: Sari Nejat Y. 
Published: August 2008

AbstractThe influence of erodent particle types on solid particle erosion of randomly oriented short glass fiber and mineral particle reinforced polyphenylene sulphide (PPS) was investigated. The solid particle erosion studies were carried out using low speed solid particle erosion test rig with 150 to 212‐μm brown fused aluminum oxide (Al2O3), 150 to 200‐μm silica sand and 150 to 250‐μm glass bead. Glass bead eroding particles appear spherical in shape whereas aluminum oxide and silica sand eroding particles have sharp and angular edges. The erosion tests were conducted at six different contact angles of 15, 30, 45, 60, 75, and 90°, respectively. The results showed a strong dependence of the eroding particle types on the erosive wear behavior of PPS composite. The peak erosion rate occurred at 45° contact angle for silica sand eroding particles while the peak erosion rate occurred at 30° contact angle for aluminum oxide and glass bead particles. The morphologies of eroded surfaces were characterized by the scanning electron microscopy. In case of aluminum oxide and silica sand, the erosive wear mechanism occurs firstly by the erosion of matrix, followed by the fracture of un‐supported fibers and their detachment; however, the erosive wear mechanism occurs different for glass bead particles. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Simultaneous determination of 76As, 122Sb and 153Sm in Chinese medicinal herbs by epithermal neutron activation analysis
Authors: Chen Chien‐Yi 
Published: August 2008

AbstractOptimal conditions for the simultaneous determination of As, Sb and Sm in Chinese medicinal herbs using epithermal neutron activation analysis were investigated. The minimum detectable concentrations of 76As, 122Sb and 153Sm in lichen and medicinal herbs depended on the weight of the irradiated sample, and irradiation and decay durations. Optimal conditions were obtained by wrapping the irradiated target with 3.2 mm borated polyethylene neutron filters, which were adopted to screen the original reactor fission neutrons and to reduce the background activities of 38Cl, 24Na and 42K. Twelve medicinal herbs, commonly consumed by Taiwanese children as a diuretic treatment, were analysed since trace elements, such as As and Sb, in these herbs may be toxic when consumed in sufficiently large quantities over a long period. Various amounts of medicinal herbs, standardised powder, lichen and tomato leaves were weighed, packed into polyethylene bags, irradiated and counted under different conditions. The results indicated that about 350 mg of lichen irradiated for 24 h and counted for 20 min following a 30–60 h decay period was optimal for irradiation in a 1011 n/cm s epithermal neutron flux. The implications of the content of the studied elements in Chinese medicinal herbs are discussed. Copyright © 2008 John Wiley & Sons, Ltd.
Polyester containing isocyanate groups—Modified epoxy resin: Rheological, dynamic‐mechanical, and impact properties
Authors: Soares Bluma G. , Gonçalez Viviane , Galimberti Rurik , Barcia Fabio L. , Sirqueira Alex S. 
Published: August 2008

AbstractLow molar mass hydroxyl‐terminated polyester was functionalized with isocyanate groups (NCO) and used to improve the impact resistance of epoxy resin (ER) cured with triethylene tetramine (TETA). The effect of polyester‐based modifiers (with or without NCO groups) on the curing rate of epoxy/TETA system was investigated by rheological techniques. It was found that the functionalized polyester decreased the gel time, indicating an accelerating effect of the curing process. In addition, significant improvement in impact resistance of the epoxy network was achieved, with low detrimental effect on the glass transition temperature and stiffness. The modified epoxy systems did not present phase‐separated morphology discernible by scanning electron microscopy, even after the curing process. The glass transition temperature of the epoxy networks was also investigated by dynamic‐mechanical analysis. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Electrodes modified with polyaminophenols: Immobilization of purines and pyrimidines
Authors: Franco Diego L. , Afonso André S. , Ferreira Lucas F. , Gonçalves Rafael A. , Boodts Julien F.C. , Brito‐Madurro Ana G. , Madurro João M. 
Published: August 2008

AbstractThis work describes the preparation of polymers potentiodynamically formed on surface of graphite electrode by anodic oxidation of 2, 3, or 4‐aminophenol monomers, as well as incorporation and detection of purine and pyrimidine bases on these modified electrodes. The electrochemical behavior of the formed films was studied by cyclic voltammetry and electrochemical impedance spectroscopy. These analyses indicate that poly‐4‐aminophenol presents the highest charge transfer rate. The surface morphology was studied by SEM and AFM. These analyses showed that the polymers present globular morphology. The immobilization and detection of purines and pyrimidines on graphite electrodes modified with poly‐aminophenols was studied by differential pulse voltammetry. It was possible to show, for the first time, that the oxidation of purine and pyrimidine bases and their mixtures takes place on modified electrodes covered with polymeric films. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
New polyaniline/polycardanol conductive blends characterized by FTIR, NIR, and XPS
Authors: Souza Fernando Gomes , Pinto José C. , Rodrigues Marcus V. , Anzai Thiago K. , Richa Priscila , Melo Príamo A. , Nele Márcio , Oliveira Geiza E. , Soares Bluma Guenther 
Published: August 2008

AbstractElectrically conducting composites based on polyaniline‐H2SO4/polycardanol were prepared with a mechanical mixing method. The influence of the composition on the electrical performance of the composites was evaluated. Materials were characterized by Fourier Transform Infrared Analysis and Near Infrared Analysis. X‐Ray Photoelectron Spectroscopy analyses were used to explain the different electrical behavior of these composites. The bioconductive materials showed low percolation thresholds and low electrical resistances, allowing for use as pressure sensing materials. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Thermogravimetric and spectrometric characterizations of poly(styrene‐co‐divinylbenzene) containing phosphinic and phosphonic acid groups
Authors: de Santa Maria Luiz Claudio , Souza Marcelo A.V. , Santos Fábio R. , Rubenich Lorna M.S. , Ferreira Maria D.J.F. , Sá Rita M.P. 
Published: August 2008

AbstractDerivatized poly(styrene‐co‐divinylbenzene) resins have been prepared from the commercial crosslinked polystyrene by the aromatic electrophilic substitution reaction using PCl3/AlCl3 or PCl5/AlCl3, followed by base‐promoted hydrolysis. The unmodified copolymer and their phosphored derivatives have been characterized by thermogravimetric (TG) analysis to evaluate their thermal stability in nitrogen atmosphere. The influence of phosphorylation and phosphonation of crosslinked copolymer on its thermal behavior was evaluated. The TG and DTG curves of modified copolymers have clearly shown two thermal degradation stages. The modified copolymers have presented higher thermal stability than unmodified one, showing that the introduction of phosphinic or phosphonic acid groups modifies their kinetic pathways. The decomposition temperatures and thermal stability were dependent on the phosphorous amount incorporated on the commercial resin. The modified copolymers were also evaluated by spectrometric method (FTIR, using KBr pellet). The phosphorous content of the modified copolymers was determined by colorimetric method based on sodium molybdate reagent (determination at 830 nm). POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Interphase phenomena in nanoparticulate filled polyurethane/poly(vinyl acetate) polymer systems
Authors: Vrsaljko Domagoj , Leskovac Mirela , Blagojević Sanja Lučić , Kovačević Vera 
Published: August 2008

AbstractPolyurethane (PU) and poly(vinyl acetate) (PVAc) are partially miscible polymers. The aim of this study was to investigate the influence of untreated and surface pretreated calcium carbonate (CaCO3) on the interphase properties of PU/PVAc polymer blends with possible compatibilization effects when the conditions of effective adhesion are achieved. With the aim to modify interface between filler and matrices, CaCO3 was pretreated by grafting PVAc on the filler surface using 60Co γ‐ray irradiation polymerization of vinyl acetate. A series of the PU/PVAc blends without and with the addition of CaCO3 were prepared using a Brabender plasticorder at 140°C. Surface characterization of the PU and PVAc polymers as well as the untreated and surface pretreated CaCO3 fillers was carried out by determination of the surface free energy. The adhesion between CaCO3 and phases in the polymer blends was predicted on the basis of the calculated adhesion parameters (interfacial free energy, spreading coefficient and work of adhesion) obtained from the surface free energy of components. Thermal and mechanical properties were investigated by tensile strength measurements and differential scanning calorimetry (DSC). The adhesion parameters were correlated with the mechanical and thermal properties as well as phase morphology observations. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Surface studies of corona treated polydimethylsiloxane‐block‐polystyrene hybrid copolymer films
Authors: Bayley G.M. , Mallon P.E. 
Published: August 2008

AbstractLinear hybrid block copolymers of polydimethylsiloxane (PDMS) and polystyrene (PS) were synthesized using living sequential anionic polymerization. Sample films of these block copolymers were thermally annealed for 48 hr at 120°C to promote phase segregation and allow for the preferential surface segregation of PDMS. The films were then exposed to corona discharge for 30 min. Optical microscopy and scanning electron microscopy (SEM) were used to identify surface cracks due to the formation of a silica‐like glassy layer after corona exposure. Slow positron beam studies were used to evaluate the degradation phenomenon and provide the first evidence of silica‐like degradation layers forming on the surface of PDMS containing hybrid polymer films, after corona exposure. It also allowed determination of the thickness of the glassy layer. Contact angle measurements also showed the first evidence that the same hydrophobic loss and recovery phenomenon for the corona treated hybrid polymer films occurs, as with pure PDMS samples. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers