bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonenhanced methods for lower‐extremity MRA: A phantom study examining the effects of stenosis and pathologic flow waveforms at 1.5T
Authors: Offerman Erik J. , Hodnett Philip A. , Edelman Robert R. , Koktzoglou Ioannis 
Published: January 2011

AbstractPurposeTo evaluate the signal properties of 2D time of flight (TOF), quiescent‐interval single‐shot (QISS), ECG‐gated 3D fast spin‐echo (FBI), and ungated 3D fast spin‐echo ghost (Ghost) magnetic resonance angiography (MRA) over a range of flow velocities in a pulsatile flow phantom with a 50% diameter stenosis at 1.5T.Materials and MethodsBlood‐mimicking fluid was pumped at eight peak flow velocities through a stenotic region in triphasic and monophasic waveforms. Vascular signal proximal, within, and distal to the stenosis was measured from the source images of the four MRA methods. Coronal maximum intensity projection images were used to compare image quality.ResultsTOF and QISS signal trends were similar, but QISS exhibited the most consistent signal across velocities. At high velocities (≥42.4 cm/s), TOF showed poststenotic signal loss that was not observed with QISS. FBI and Ghost signals peaked at low velocities (3.9–9.7 cm/s) without flow compensation and at high velocities (≥64.6 cm/s) with flow compensation.ConclusionFBI and Ghost demonstrated dependence on blood flow velocity and flow compensation. TOF was sensitive to flow artifacts at high velocities. QISS proved most robust for accurately depicting the normal lumen and stenosis under a wide range of flow conditions. Monophasic and triphasic flow did not appreciably affect the signal performance of any method. J. Magn. Reson. Imaging 2011;33:401–408. © 2011 Wiley‐Liss, Inc.
Evaluation of possible drug–drug interaction between gadoxetic acid and erythromycin as an inhibitor of organic anion transporting peptides (OATP)
Authors: Huppertz Alexander , Breuer Josy , Fels Lueder M. , Schultze‐Mosgau Marcus , Sutter Gabriele , Klein Stefan , Frericks Bernd , Hamm Bernd , Wagner Moritz 
Published: January 2011

AbstractPurposeTo evaluate if erythromycin compromises liver‐specific enhancement of gadoxetic acid; both compounds competing in organic anion transporting peptides (OATP) ‐mediated hepatocytic uptake.Materials and MethodsThe study was approved by institutional review board. Twelve healthy subjects (nine men, three woman; mean age, 38.7 years) were examined twice by MR imaging with prior administration of NaCl solution (placebo) or 1000 mg of erythromycin following a randomized sequence. Gadoxetic acid (0.025 mmol/kg body weight) was administered 15 min after the end of infusions. Pre‐ and 20 min postcontrast two‐dimensional gradient‐recalled‐echo sequences were acquired. Relative enhancements of liver parenchyma and ratio of means were calculated from signal intensity measurements. Plasma levels of gadoxetic acid and erythromycin were determined and given in geometric means and coefficients of variation (CV).ResultsConcentration of erythromycin directly after end of infusion was 13.9 mg/L (CV 14.9%). Gadolinium plasma concentrations 5 min after gadoxetic acid administration were 138.7 μmol/L (CV 20.4%) after erythromycin infusion and 129.6 μmol/L (CV 22.8%) after placebo. Mean relative enhancements of liver parenchyma were 88.1 (SD 24.9%) after erythromycin infusion and 92.6 (SD 17.9%) after placebo. Ratio of relative enhancements was 0.951 (95% confidence interval, 0.833; 1.061; statistically not significant).ConclusionCoadministration of erythromycin has no effect on gadoxetic acid enhanced liver MR imaging. J. Magn. Reson. Imaging 2011;33:409–416. © 2011 Wiley‐Liss, Inc.
MR spectroscopy of normative premature newborns
Authors: Xu Duan , Bonifacio Sonia L. , Charlton Natalie N. , P. Vaughan Charles , Lu Ying , Ferriero Donna M. , Vigneron Daniel B. , Barkovich A. James 
Published: January 2011

AbstractPurposeTo establish normative metabolite ratios throughout the newborn brain using three‐dimensional (3D) MR spectroscopic imaging (MRSI).Materials and MethodsMRI and MRSI have been valuable tools for assessing normal and abnormal neuronal maturation for newborns. In this study, we performed whole brain 3D MRSI in addition to comprehensive anatomic and other functional imaging methods to examine maturation. Fifty‐five newborn subjects (28.4 ± 2.6 weeks postconception age at birth, 34.1 ± 3.1 weeks postconception age at scan, 32 males and 23 females) had high quality MRSI studies (104 exams) and normal neurodevelopmental outcome (neuromotor score = 0, mental development index score > 85) at age 12 months.ResultsThe NAA to Cho ratio increased significantly with age for all regions. Lac to NAA ratio decreased significantly with age in the regions of thalamus, basal ganglia, cortical spinal tract, and parietal white matter, and showed a decreasing trend in the other regions.ConclusionBrain metabolites can be obtained through in vivo 3D MRSI and used to monitor newborn brain maturation. J. Magn. Reson. Imaging 2011;33:306–311. © 2011 Wiley‐Liss, Inc.
Pacemaker lead tip heating in abandoned and pacemaker‐attached leads at 1.5 tesla MRI
Authors: Langman Deborah A. , Goldberg Ira B. , Finn J. Paul , Ennis Daniel B. 
Published: January 2011

AbstractPurposeTo assess the risk of RF‐induced heating in pacemaker‐attached and abandoned leads using in vitro temperature measurements at 1.5 Tesla as a function of lead length.Materials and MethodsFive custom lead lengths, 20–60 cm, were exposed to a uniform magnitude and phase radiofrequency electric field to examine the effect of lead length on pacemaker lead tip heating for pacemaker‐attached and abandoned pacemaker leads.ResultsAbandoned and pacemaker‐attached leads show resonant heating behavior and maximum heating occurs at different lead lengths due to the differences in termination conditions. For clinical lead lengths (40–60 cm) abandoned leads exhibited greater lead tip heating compared with pacemaker‐attached leads.ConclusionCurrent recommendations for MRI pacemaker safety should highlight the possible increased risk for patients with abandoned leads as compared to pacemaker‐attached leads. J. Magn. Reson. Imaging 2011;33:426–431. © 2011 Wiley‐Liss, Inc.
Aliasing artifacts with the BLADE technique: Causes and effective suppression
Authors: Kojima Shinya , Morita Satoru , Ueno Eiko , Hirata Masami , Shinohara Hiroyuki , Komori Akiyoshi 
Published: January 2011

AbstractPurpose:To elucidate the causes of aliasing artifacts with the BLADE technique and clarify the effective suppression methods.Materials and Methods:We separately observed the aliasing artifacts of BLADE from features inside and then outside the defined field‐of‐view (FOV) using phantom studies. The effectiveness of suppressing them with phase oversampling (POS) and presaturation pulses (SAT) was evaluated. Finally, our observations were confirmed for a healthy volunteer.Results:Characteristic aliasing artifacts were observed from both inside and outside the FOV. Those from inside the FOV were sufficiently suppressed by using a POS of 25%, considering the acquisition time prolongation. Those from outside the FOV were nearly suppressed using SAT outside the FOV without selecting needless receiver coils. Aliasing artifacts on the coronal images of the head and neck with a healthy volunteer were completely suppressed by a combination of using a POS of 25% and using SAT on all four sides outside the FOV.Conclusion:The characteristic aliasing artifacts of BLADE are caused from both inside and outside the defined FOV. They can be effectively suppressed by a combination of using a POS of 25% and using SAT on all four sides outside the FOV. J. Magn. Reson. Imaging 2011;33:432–440. © 2011 Wiley‐Liss, Inc.
Prospective motion correction for magnetic resonance spectroscopy using single camera retro‐grate reflector optical tracking
Authors: Andrews‐Shigaki Brian C. , Armstrong Brian S.R. , Zaitsev Maxim , Ernst Thomas 
Published: January 2011

AbstractPurpose:To introduce and evaluate a method of prospective motion correction for localized proton magnetic resonance spectroscopy (1H‐MRS) using a single‐camera optical tracking system.Materials and Methods:Five healthy participants were scanned at 3T using a point‐resolved spectroscopic sequence (PRESS) with a motion‐tracking module and phase navigator. Head motion in six degrees was tracked with a Retro‐Grate Reflector (RGR) tracking system and target via a mirror mounted inside the bore. Participants performed a series of three predetermined motion patterns during scanning.Results:Left–right rotation (Rz) (average 12°) resulted in an increase in the total choline to total creatine ratio (Cho/Cr) of +14.6 ± 1.5% (P= 0.0009) for scans without correction, but no change for scans with correction (+1.1 ± 1.5%;P= 0.76). Spectra with uncorrected Z‐translations showed large lipid peaks (skull) with changes in Cho/Cr of −13.2 ± 1.6% (P= 0.02, no motion correction) and −2.2 ± 2.4% (P= 0.51) with correction enabled. There were no significant changes in the ratios of N‐acetylaspartate, glutamate+glutamine, or myo‐inositol to creatine compared to baseline scans for all experiments.Conclusion:Prospective motion correction for 1H‐MRS, using single‐camera RGR tracking, can reduce spectral artifacts and quantitation errors in Cho/Cr ratios due to head motion and promises improved spectral quality and reproducibility. J. Magn. Reson. Imaging 2011. © 2011 Wiley‐Liss, Inc.
Rubbers Based on Conjugated Soybean Oil: Synthesis and Characterization
Authors: Valverde Marlen , Yoon Sungho , Bhuyan Satyam , Larock Richard C. , Kessler Michael R. , Sundararajan Sriram 
Published: January 2011

AbstractA range of bio‐based rubbery thermosets have been synthesized by the cationic copolymerization of conjugated soybean oil, styrene, and 1,5‐hexadiene or isoprene as flexible crosslinkers. The thermal, and mechanical properties, as well as the wear behavior, of these new bio‐rubbers are reported. The amount of styrene and the type of diene incorporated have the greatest influence on the properties of the final materials. The largest variations are found in glass transition temperature, storage modulus, tan δ values, crosslink density, and abrasive wear depth, while thermal degradation and extraction analyses showed minimal variations with changes in composition. magnified image
Amphiphilic Peptide–Polymer Conjugates with Side‐Conjugation
Authors: Dube Nikhil , Presley Andrew D. , Shu Jessica Y. , Xu Ting 
Published: January 2011

AbstractPolymers conjugated to the exterior of a protein mediate its interactions with surroundings, enhance its processability and can be used to direct its macroscopic assemblies. Most studies to date have focused on peptide–polymer conjugates based on hydrophilic polymers. Engineering amphiphilicity into protein motifs by covalently linking hydrophobic polymers has the potential to interface peptides and proteins with synthetic polymers, organic solvents, and lipids to fabricate functional hybrid materials. Here, we synthesized amphiphilic peptide–polymer conjugates in which a hydrophobic polymer is conjugated to the exterior of a heme‐binding four‐helix bundle and systematically investigated the effects of the hydrophobicity of the conjugated polymer on the peptide structure and the integrity of the heme‐binding pocket. In aqueous solution with surfactants present, the side‐conjugated hydrophobic polymers unfold peptides and may induce an α‐helix to β‐sheet conformational transition. These effects decrease as the polymer becomes less hydrophobic and directly correlate with the polymer hydrophobicity. Upon adding organic solvent to solubilize the hydrophobic polymers, however, the deleterious effects of hydrophobic polymers on the peptide structures can be eliminated. Present studies demonstrate that protein structure is sensitive to the local environment. It is feasible to dissolve amphiphilic peptide–polymer conjugates in organic solvents to enhance their solution processability while maintaining the protein structures. magnified image
A Nanotechnology Pathway to Arresting Phase Separation in Soft Nanocomposites
Authors: Pomposo José A. , de Luzuriaga Alaitz Ruiz , García Iñaki , Etxeberria Agustín , Colmenero Juan 
Published: January 2011

AbstractDirect observation of the miscibility improving effect of ultra‐small polymeric nanoparticles (radius ≈4 nm) in model systems of soft nanocomposites is reported. We have found thermodynamically arrested phase separation in classical poly(styrene) (PS)/poly(vinyl methyl ether) blends when PS linear chains were totally replaced by ultra‐small, single chain PS nanoparticles, as determined by thermo‐optical microscopy measurements. Partial arrested phase splitting on heating was observed when only some of the PS chains were replaced by unimolecular PS nanoparticles, leading to a significant increase of the lower critical solution temperature (LCST) of the system (up to 40 °C at 15 vol.‐% nanoparticle content). Atomic force microscopy and rheological experiments supported these findings. Thermodynamic arrest of the phase separation process induced by replacement of linear polymer chains by unimolecular polymer nanoparticles could have significant implications for industrial applications requiring soft nanocomposite materials with excellent nanoparticle dispersion in a broad temperature range. magnified image
BIBuilder: Exhaustive Searching for De Novo Ligands
Authors: Teodoro Miguel , Muegge Ingo 
Published: January 2011

AbstractThe de novo design program BIBuilder has been developed for structure‐based as well as ligand‐based design. Incremental growth allows for the de novo design of novel molecules with putative bioactivity. In addition, linking between existing fragments enables scaffold hopping tasks. A RECAP‐based retrosynthetic fragment connection protocol yields ligands that are synthesizable. An exhaustive fragment search protocol assures that known ligands are always found if all necessary fragments exist in the database of building blocks. To make an exhaustive search possible, a strategy of connecting tens of thousands of unique fragments with only three growth or linking steps is adopted resulting in the generation of up to 1016 possible compounds with up to 1021 conformations. Ligands are scored by shape and pharmacophore matches that can be individually weighted. Final hits are evaluated through customizable scoring functions. Estrogen receptor, COX‐2, renin, and NNRTI examples illustrate the performance of BIBuilder in different tasks such as structure‐based or ligand‐based growing and linking. Not only are known ligands reproduced in all test cases but a number of interesting alternative scaffolds and ligands have been found.
Role of Metallic NiCr Dots on the Adhesion, Electrical, Optical and Mechanical Properties of Diamond‐like Carbon Thin Films
Authors: Dwivedi Neeraj , Kumar Sushil , Rauthan Chandra Mohan Singh , Panwar Omvir Singh 
Published: January 2011

AbstractThe effect of thermally evaporated metallic NiCr dots on the adhesion, electrical, optical and the mechanical properties of RF‐PECVD grown diamond‐like carbon (DLC) thin films was investigated. The DLC films deposited over NiCr dots containing substrates exhibited a strong adhesion to the substrate. The observed drastic increase in magnitude of the current and the decrease of optical band gap due to presence of NiCr dots revealed a considerable improvement in their electrical and optical properties, respectively. Further, load versus displacement curves were employed to estimate the hardness (H), elastic modulus (E), plastic resistance parameter (H/E) and elastic recovery (ER). The values of H and E in NiCr dots containing DLC films were found to be comparatively less than that of DLC films. Overall, NiCr metal dots improved adhesion, optical and electrical properties of DLC films with a little deterioration in their mechanical properties (e.g. H, E, ER and H/E).
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Plasma‐Assisted Synthesis of Chlorinated Polyvinyl Chloride (CPVC) Using a Gas–Solid Contacting Process
Authors: Lu Wei , Cao Tengfei , Wang Qi , Cheng Yi 
Published: January 2011

AbstractPlasma‐assisted synthesis of CPVC, using a gas–solid contactor, is presented as a novel process of PVC chlorination. The basic principle is to use cold plasma to generate free radical chlorine and activate the surfaces of PVC particles at the same time. Accordingly, the chlorination process can be decoupled into two steps: plasma‐enhanced chlorination on the particle surface and chlorine transfer from the surface to the core of the particle. Experiments were carried out in a DBD plasma fixed‐bed reactor. The results demonstrated the high efficiency of this process, i.e., a total of 3 h operation with plasma can achieve up to 67% of the chlorine content in PVC particles. The characterization results by SEM/EDS, TGA, and Raman spectra showed that CPVC made by this process had the desired microstructure and the thermal stability similar to that of the commercial CPVC products.
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SuperHydrophobic and SuperHydrophilic Polycarbonate by Tailoring Chemistry and Nano‐texture with Plasma Processing
Authors: Palumbo Fabio , Di Mundo Rosa , Cappelluti Davide , d'Agostino Riccardo 
Published: January 2011

AbstractVersatility of plasma processing is demonstrated for the preparation of nanotextured polycarbonate surfaces with superior wettability properties. Tens of nanometers wide pillar structures are produced on the polymer by means of oxygen plasma etching, inducing on the surface a pronounced hydrophilic behavior. As well known from literature, however, treated surfaces undergo a fast hydrophobic recovery, but a post‐deposition process can ensure the formation of transparent and stable superhydrophylic or superhydrophobic surfaces.
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Physico‐Chemical Characterization of Methyl Isobutyrate‐based Plasma Polymer Films
Authors: Denis Laurent , Renaux Fabian , Cossement Damien , Bittencourt Carla , Tuccitto Nunzio , Licciardello Antonino , Hecq Michel , Snyders Rony 
Published: January 2011

AbstractMethyl isobutyrate is plasma‐polymerized varying the precursor flow rate (Φp), the working pressure (p) and the radiofrequency power injected in the discharge (PRF). Through the use of an experimental design, PRF reveals to be the key parameter regarding the incorporation of oxygen‐based functionalities in the plasma polymer films (PPFs). Combining the use of X‐ray photoelectron spectroscopy (XPS), time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) and principal component analysis (PCA), our results demonstrate that an increase of PRF (i) lowers the incorporation of the precursor ester groups within the PPFs and (ii) amplifies the PPF crosslinking density (χ). A correlation between the PPF physico‐chemistry and the plasma composition is established using residual gas analysis mass spectrometry. It is shown that an increase of PRF increases both the extent of the precursor fragmentation and the production of non‐reactive oxygen‐based species in the plasma that do not contribute to the PPF growth. Incidentally, in the PRF range studied, the total amount of oxygen‐based functionalities incorporated in the PPFs (at.%O) varies from 23.9 to 10.1 at.%.
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A Novel Technique Toward Bipolar Films Containing Alternating Nano–Layers of Allylamine and Acrylic Acid Plasma Polymers for Biomedical Application
Authors: Yang Zhilu , Lei Xingjiang , Wang Jin , Luo Rifang , He Tingting , Sun Hong , Huang Nan 
Published: January 2011

AbstractAn intentional and defined grafting of the material surface with multiple positive/negative charges produced by functional groups is desired for biomedical applications. In this work, multistacked organic bipolar films containing alternating nano‐layers of plasma polymerized acrylic acid (PPAac) and plasma polymerized allylamine (PPAam) are investigated in order to prepare highly polarized surfaces with positive/negative charges. Two kinds of composite films fabricated according to different depositing sequences and with –COOH or –NH2functional groups onto their outermost surfaces are prepared. The results of ATR‐FTIR and XPS demonstrate that a significant number of COO–and –NHpolar entities, generated from the interaction of PPAac and PPAam films, are present in these multistacked organic bipolar films. Furthermore, the remarkably increased polar surface energy of these composite films, compared with pure PPAac and PPAam films, reveals that the presence of the COO–and NHpolar entities induces strong dipole orientation polarizability, and results in the redistribution of charges. The results suggest that the surface with highly polarized –COOH and –NH2groups have high surface charges and chemical reactivity. These surfaces show promising applications for biomolecules binding and cell growth.magnified image
Local oscillations in different models of the coherent bcc–hcp boundary in 4He and metals
Authors: Lykah Victor A. , Syrkin Eugene S. 
Published: January 2011

AbstractSmall local vibrations of the order parameter (the relative displacement of atomic planes) on the coherent phase boundary (PB) in the bcc–hcp 4He crystal are investigated theoretically. Dynamical differential equations for small values of the perturbations of the order parameter are obtained. On the coherent PB bcc–hcp for double‐ and triple‐well models the shape and the spectrum are found for small local vibrations of the order parameter. Characteristic frequencies are found and estimated. It is shown that the bcc–hcp boundary in the 4He crystal is a very soft system. This fact may explain the high degree of damping of 3He excitations in nuclear magnetic resonance (NMR) experiments.
High‐pressure lattice dynamics and thermodynamics in BaO
Authors: Lukačević I. 
Published: January 2011

AbstractUsing density functional theory and density functional perturbation theory we have studied lattice dynamics, dielectric and thermodynamic properties of the rocksalt (NaCl) phase of BaO under hydrostatic pressure, a material which has lately aroused many interests. Studying the lattice dynamics of the rocksalt phase at various pressures, in the range of the phase stability, we have found a lattice dynamical instability which governs the phase transition to NiAs phase. Monitoring the behaviour of the found soft mode, we have calculated the transition pressure of 10 GPa in an excellent agreement with experimental data. Lattice dynamics calculations reveal that the rocksalt structure is unstable with respect to soft transversal acoustic mode at a single point on the Brillouin zone boundary, which points to the fact that the transition is of displacive type. The observed pressure of the phase transition in structural measurements is reproduced more accurately than in previous calculations, which used enthalpy comparison method. Calculating the volume change during the phase transition from rocksalt to NiAs phase, we conclude that the phase transition might be of the second or weakly first order. Dielectric and thermodynamic properties at high pressures are also given. An anomalous thermal expansion coefficient is found up to about 10 K.
Elastic and electronic properties of hexagonal rhenium sub‐nitrides Re3N and Re2N in comparison withhcp‐Re and wurtzite‐like rhenium mononitride ReN
Authors: Bannikov Vyacheslav V. , Shein Igor R. , Ivanovskii Alexander L. 
Published: January 2011

AbstractVery recently, two hexagonal rhenium sub‐nitrides Re3N and Re2N, which belong to a rather rare group of known metal‐rich (M/N > 1) nitrides of heavy 4d, 5d metals, have been successfully synthesized, and their potential technological applications as ultra‐incompressible materials have been proposed. In this work, we present a detailedab initiostudy of recently synthesized rhenium sub‐nitrides in comparison withhcp‐Re and wurtzite‐like rhenium mono‐nitride ReN, with the purpose to evaluate the trends of the elastic, electronic properties, and chemical bonding in the series of these hexagonal systems as a function of the Re/N stoichiometry: Re → Re3N → Re2N → ReN.