bluuebunny/crossref_metadata_2025_split huggingface dataset:
NMR spectra, GIAO and charge density calculations of five‐membered aromatic heterocycles
Authors: Katritzky Alan R. , Akhmedov Novruz G. , Doskocz Jacek , Mohapatra Prabhu P. , Hall C. Dennis , Güven Alâattin 
Published: May 2007

AbstractThe B3LYP/6‐31 + G(d) molecular geometry optimized structures of 17 five‐membered heterocycles were employed together with the gauge including atomic orbitals (GIAO) density functional theory (DFT) method at the B3LYP/6‐31 + G(d,p), B3LYP/6‐311 + + G(d,p) and B3LYP/6‐311 + G(2d,p) levels of theory for the calculation of proton and carbon chemicals shifts and coupling constants. The method of geometry optimization for pyrrole (1), N‐methylpyrrole (2) and thiophene (7) using the larger 6‐311 + + G(d,p) basis sets at the B3LYP/6‐31 + G(d,p), B3LYP/6‐311 + + G(d,p), B3LYP/6‐31 + G(2d,p) and B3LYP/cc‐pVTZ levels of theory gave little difference between calculated and experimental values of coupling constants. In general, the 1H and 13C chemical shifts for all compounds are in good agreement with theoretical calculations using the smaller 6‐31 basis set. The values of nJHH(n = 3, 4, 5) and rmnJCH(n = 1, 2, 3, 4) were predicted well using the larger 6‐31 + G(d,p) and 6‐311 + + G(d,p) basis sets and at the B3LYP/6‐31 + G(d,p), B3LYP/6‐311 + + G(d,p), B3LYP/6‐31 + G(2d,2p) levels of theory. The computed atomic charges [Mülliken; Natural Bond Orbital Analysis (NBO); Merz‐Kollman (MK); CHELP and CHELPG] for the B3LYP/6‐311 + + G(d,p) geometry optimized structures of 1–17 were used to explore correlations with the experimental proton and carbon chemical shifts. Copyright © 2007 John Wiley & Sons, Ltd.
1H and 13C NMR assignments for two new angular furanocoumarin glycosides from Peucedanum praeruptorum
Authors: Chang Haitao , Okada Yoshihito , Okuyama Toru , Tu Pengfei 
Published: May 2007

AbstractTwo novel angular‐type furanocoumarin glycosides, peucedanoside A (1) and peucedanoside B (2), along with a known compound apterin (3), were isolated from the roots of Peucedanum praeruptorum Dunn. Their chemical structures were determined by MS, NMR spectroscopy and chemical analysis. Complete assignments of the 1H and 13C NMR spectroscopic data were achieved by 1D and 2D NMR experiments including DEPT, HSQC, HMBC and ROESY. Copyright © 2007 John Wiley & Sons, Ltd.
Passive catheter tracking during interventional MRI using hyperpolarized 13C
Authors: Magnusson Peter , Johansson Edvin , Månsson Sven , Petersson J. Stefan , Chai Chun‐Ming , Hansson Georg , Axelsson Oskar , Golman Klaes 
Published: May 2007

AbstractInterventional procedures in MRI can be performed preclinically using active or passive catheter‐tracking methods. A novel passive nonproton technique is suggested that uses a catheter filled with a hyperpolarized 13C contrast agent. A prototype three‐lumen catheter was built with two closed lumens containing a flowing hyperpolarized 13C contrast agent. Entire‐length 13C catheter projection visualization could be performed in vivo with a catheter SNR of ∼80, one dual projection frame per ∼700 ms, and an in‐plane resolution of 2 × 2 mm2 while traveling through the aorta of a pig. The traveling path of the 13C catheter was visualized after back‐projection catheter reconstruction and after image fusion with an anatomical offline proton road map. Catheter length visualization was aided by an oblique planar visualization mode. The high catheter signal demonstrated, together with the entire catheter length visualization and high surrounding soft‐tissue contrast, warrants further development into a real‐time technique. Magn Reson Med 57:1140–1147, 2007. © 2007 Wiley‐Liss, Inc.
High‐field actively detuneable transverse electromagnetic (TEM) coil with low‐bias voltage for high‐power RF transmission
Authors: Avdievich Nikolai I. , Bradshaw Ken , Kuznetsov Andrey M. , Hetherington Hoby P. 
Published: May 2007

AbstractThe design and construction of a 4T (170 MHz) transverse electromagnetic (TEM) actively detuneable quadrature head coil is described. Conventional schemes for active detuning require high negative bias voltages (>300 V) to prevent leakage of RF pulses with amplitudes of 1–2 kW. To extend the power handling capacity and avoid the use of high DC bias voltages, we developed an alternate method of detuning the volume coil. In this method the PIN diodes in the detuning circuits are shorted when the RF volume coil is tuned, and negatively biased with –12 V when the coil is detuned. To preserve the high QU/QL ratio of the TEM coil, we modified the method of Nabetani and Watkins (Proceedings of the 13th Annual Meeting of ISMRM, Kyoto, Japan, 2004, abstract 1574) by utilizing a high‐impedance (∼200 Ω), lumped‐element, quarter‐wavelength transformer. A QU of 500 was achieved for the detuneable TEM, such that incorporation of the detuning network had minimal effect (<1 dB) on the performance of the coil in vivo. Magn Reson Med 57:1190–1195, 2007. © 2007 Wiley‐Liss, Inc.
Longitudinal gradient coil optimization in the presence of transient eddy currents
Authors: Trakic A. , Liu F. , Lopez H. Sanchez , Wang H. , Crozier S. 
Published: May 2007

AbstractThe switching of magnetic field gradient coils in magnetic resonance imaging (MRI) inevitably induces transient eddy currents in conducting system components, such as the cryostat vessel. These secondary currents degrade the spatial and temporal performance of the gradient coils, and compensation methods are commonly employed to correct for these distortions. This theoretical study shows that by incorporating the eddy currents into the coil optimization process, it is possible to modify a gradient coil design so that the fields created by the coil and the eddy currents combine together to generate a spatially homogeneous gradient that follows the input pulse. Shielded and unshielded longitudinal gradient coils are used to exemplify this novel approach. To assist in the evaluation of transient eddy currents induced within a realistic cryostat vessel, a low‐frequency finite‐difference time‐domain (FDTD) method using the total‐field scattered‐field (TFSF) scheme was performed. The simulations demonstrate the effectiveness of the proposed method for optimizing longitudinal gradient fields while taking into account the spatial and temporal behavior of the eddy currents. Magn Reson Med 57:1119–1130, 2007. © 2007 Wiley‐Liss, Inc.
Functional MRI impulse response for BOLD and CBV contrast in rat somatosensory cortex
Authors: Silva Afonso C. , Koretsky Alan P. , Duyn Jeff H. 
Published: May 2007

AbstractThe contrast mechanism in functional MRI (fMRI) results from several vascular processes with different time scales, thus establishing a finite temporal resolution to fMRI experiments. In this work we measured the blood oxygen level‐dependent (BOLD) and iron‐oxide‐derived cerebral blood volume (CBV) impulse response (IR) in a rat model of somatosensory brain activation at 11.7T. A binary m‐sequence probe method was used to obtain high‐sensitivity single‐pixel estimates of the IR, from which two parameters—the full width at half maximum (FWHM) and the time to peak (TTP)—were determined as indices of the temporal resolution of the hemodynamic response (HDR). The results (N = 11) show that the CBV IR (N = 5, subset) is significantly narrower (FWHM = 1.37 ± 0.11 s), and peaks earlier (TTP = 1.65 ± 0.15 s) than the BOLD IR (N = 11, FWHM = 1.92 ± 0.22 s and TTP = 2.18 ± 0.14 s, respectively). These findings indicate that neurovascular control mechanisms have a temporal resolution better than 1.5 s FWHM, and point to a substantial contribution to BOLD of the dispersive transit of oxygenated hemoglobin across the rat vasculature, bringing important implications for the ultimately attainable temporal resolution of fMRI. Magn Reson Med 57:1110–1118, 2007. © 2007 Wiley‐Liss, Inc.
Temporally constrained reconstruction of dynamic cardiac perfusion MRI
Authors: Adluru Ganesh , Awate Suyash P. , Tasdizen Tolga , Whitaker Ross T. , DiBella Edward V.R. 
Published: May 2007

AbstractDynamic contrast‐enhanced (DCE) MRI is a powerful technique to probe an area of interest in the body. Here a temporally constrained reconstruction (TCR) technique that requires less k‐space data over time to obtain good‐quality reconstructed images is proposed. This approach can be used to improve the spatial or temporal resolution, or increase the coverage of the object of interest. The method jointly reconstructs the space‐time data iteratively with a temporal constraint in order to resolve aliasing. The method was implemented and its feasibility tested on DCE myocardial perfusion data with little or no motion. The results obtained from sparse k‐space data using the TCR method were compared with results obtained with a sliding‐window (SW) method and from full data using the standard inverse Fourier transform (IFT) reconstruction. Acceleration factors of 5 (R = 5) were achieved without a significant loss in image quality. Mean improvements of 28 ± 4% in the signal‐to‐noise ratio (SNR) and 14 ± 4% in the contrast‐to‐noise ratio (CNR) were observed in the images reconstructed using the TCR method on sparse data (R = 5) compared to the standard IFT reconstructions from full data for the perfusion datasets. The method has the potential to improve dynamic myocardial perfusion imaging and also to reconstruct other sparse dynamic MR acquisitions. Magn Reson Med 57:1027–1036, 2007. © 2007 Wiley‐Liss, Inc.
Human brain‐structure resolved T2 relaxation times of proton metabolites at 3 tesla
Authors: Zaaraoui Wafaa , Fleysher Lazar , Fleysher Roman , Liu Songtao , Soher Brian J. , Gonen Oded 
Published: May 2007

AbstractThe transverse relaxation times, T2, of N‐acetylaspartate (NAA), total choline (Cho), and creatine (Cr) obtained at 3T in several human brain regions of eight healthy volunteers are reported. They were obtained simultaneously in 320 voxels with three‐dimensional (3D) proton MR spectroscopy (1H‐MRS) at 1 cm3 spatial resolution. A two‐point protocol, optimized for the least error per given time by adjusting both the echo delay (TEi) and number of averages, Ni, at each point, was used. Eight healthy subjects (four males and four females, age = 26 ± 2 years) underwent the hour‐long procedure of four 15‐min, 3D acquisitions (TE1 = 35 ms, N1 = 1; and TE2 = 285 ms, N2 = 3). The results reveal that across all subjects the NAA and Cr T2s in gray matter (GM) structures (226 ± 17 and 137 ± 12 ms, respectively) were 13–17% shorter than the corresponding T2s in white matter (WM; 264 ± 10 and 155 ± 7 ms, respectively). The T2s of Cho did not differ between GM and WM (207 ± 17 and 202 ± 8, respectively). For the purpose of metabolic quantification, these values justify to within ±10% the previous use of one T2 per metabolite for 1) the entire brain and 2) all subjects. These T2 values (which to our knowledge were obtained for the first time at this field, spatial resolution, coverage, and precision) are essential for reliable absolute metabolic quantification. Magn Reson Med 57:983–989, 2007. © 2007 Wiley‐Liss, Inc.
Uncertain policy for an uncertain world: The case of social security
Authors: Sabelhaus John , Topoleski Julie 
Published: May 2007

AbstractAnalysis and discussion of Social Security policy are usually based on expected fiscal and societal outcomes. However, future demographic and economic trends are uncertain, and thus ultimate outcomes for aggregate system financial flows and the distribution of taxes and benefits across generations are uncertain. This paper analyzes a state‐dependent approach to policy in which future Social Security benefit formulas are tied to realized economic and demographic outcomes over time. The results, based on a microsimulation model with stochastic capabilities, show the extent to which it is possible to systematically address uncertainty about system finances and distributional outcomes. © 2007 by the Association for Public Policy Analysis and Management
Microstructure and nematic transition in thermotropic liquid crystalline fibers and their single polymer composites
Authors: Cohen Estelle Kalfon , Marom Gad , Weinberg Amotz , Wachtel Ellen , Migliaresi Claudio , Pegoretti Alessandro 
Published: May 2007

AbstractWe describe a new single polymer composite (SPC) prepared from two liquid crystalline vectran fibers. Vectran M is the as‐spun fiber while vectran HS is the high‐strength version. A study of the morphology of the pristine materials shows that the two fibers have different crystal structures. The wide‐angle X‐ray diffraction (WAXD) data confirm the presence of the so‐called pseudo‐hexagonal (PH) unit cell in vectran M, while an orthorhombic structure is revealed in the vectran HS fibers. A transition to the nematic phase is observed by in situ X‐ray diffraction at ∼277°C for the M fibers and at ∼315°C for the HS fibers. During the compaction process, the orientation of the reinforcing fibers is well maintained and the transition to a nematic phase seems to be delayed by processing at high applied pressure. Concomitantly, vectran M loses its orientation and the transition to the nematic phase disappears. Copyright © 2007 John Wiley & Sons, Ltd.
Oncogenic role of JC virus in lung cancer
Authors: Zheng H , Aziz HO Abdel , Nakanishi Y , Masuda S , Saito H , Tsuneyama K , Takano Y 
Published: May 2007

AbstractThe JC virus (JCV) infects a large proportion of the population world wide and can cause progressive mulitifocal leucoencephalopathy in the context of immunodeficiency. Recent reports provide evidence that it may also be oncogenic. Here, JCV was examined by targeting its T‐antigen in lung carcinomas (n = 103) and normal lung tissues (n = 18) by nested‐PCR followed by Southern blot, real‐time PCR, immunohistochemistry, in situ hybridization and in situ PCR. Additionally, expression of Ki‐67, caspase‐3, β‐catenin, p53, and Rb was analysed by immunohistochemistry on tissue microarrays of lung carcinomas. Copy numbers of JCV were compared with clinicopathological features. Normal lung tissue was positive significantly less frequently, and contained a lower copy number of JCV than lung carcinomas (p < 0.05), and copies were lower in lung adenocarcinomas than in squamous, small or large cell carcinomas (p < 0.05). In situ PCR and immunolabelling revealed JCV positivity in the nuclei of lung carcinoma cells. The JCV copy number correlated closely with sex, and expression of Ki‐67 and membrane β‐catenin (p < 0.05), but not with age, tumour size, pleural invasion, lymph node metastasis, expression of caspase‐3, cytoplasmic β‐catenin, p53 or Rb, prognosis, smoking or cancer family history (p > 0.05). Age and UICC staging were independent prognostic factors for lung carcinoma patients. These data suggest that JCV may be involved in lung carcinogenesis, especially in tumour types other than adenocarcinoma. Lung carcinomas with higher JCV copy numbers display high proliferation and down‐regulation of cell adhesion mediated by membrane β‐catenin. Copyright © 2007 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
A prospective study on parental coping 4 months after termination of pregnancy for fetal anomalies
Authors: Korenromp M. J. , Page‐Christiaens G. C. M. L. , van den Bout J. , Mulder E. J. H. , Hunfeld J. A. M. , Potters C. M. A. A. , Erwich J. J. H. M. , van Binsbergen C. J. M. , Brons J. T. J. , Beekhuis J. R. , Omtzigt A. W. J. , Visser G. H. A. 
Published: May 2007

AbstractObjectiveTo identify short‐term factors influencing psychological outcome of termination of pregnancy for fetal anomaly, in order to define those patients most vulnerable to psychopathology.Study DesignA prospective cohort of 217 women and 169 men completed standardized questionnaires 4 months after termination. Psychological adjustment was measured by the Inventory of Complicated Grief (ICG), the Impact of Event Scale (IES), the Edinburgh Postnatal Depression Scale (EPDS), and the Symptom Checklist‐90 (SCL‐90).ResultsWomen and men showed high levels of posttraumatic stress (PTS) symptoms (44 and 22%, respectively) and symptoms of depression (28 and 16%, respectively). Determinants of adverse psychological outcome were the following: high level of doubt in the decision period, inadequate partner support, low self‐efficacy, lower parental age, being religious, and advanced gestational age. Whether the condition was Down syndrome or another disability was irrelevant to the outcome. Termination did not have an important effect on future reproductive intentions. Only 2% of women and less than 1% of men regretted the decision to terminate.ConclusionTermination of pregnancy (TOP) for fetal anomaly affects parents deeply. Four months after termination a considerable part still suffers from posttraumatic stress symptoms and depressive feelings. Patients who are at high risk could benefit from intensified support. Copyright © 2007 John Wiley & Sons, Ltd.
Relaxation behavior of conductive carbon black reinforced EPDM microcellular vulcanizates
Authors: Mahapatra S.P. , Sridhar V. , Chaudhary R.N.P. , Tripathy D.K. 
Published: May 2007

AbstractDynamic mechanical analysis and dielectric relaxation spectra of conductive carbon black reinforced microcellular EPDM vulcanizates were used to study the relaxation behavior as a function of temperature (−90 to +100°C) and frequency (0.01–105Hz). The effect of filler and blowing agent loadings on dynamic mechanical and dielectric relaxation characteristics has been investigated. The effect of filler and blowing agent loadings on glass transition temperature was marginal for all the composites (Tgvalue was in the range of −39 to −35°C), which has been explained on the basis of relaxation dynamics of polymer chains in the vicinity of fillers. Strain‐dependent dynamical parameters were evaluated at dynamic strain amplitudes of 0.07–5%. The nonlinearity in storage modulus has been explained based on the concept of filler–polymer interaction and interaggregate attraction (filler networking) of carbon black. The variation in real and complex part of impedance with frequency has been studied as a function of filler and blowing agent loading. Additionally, the effect of crosslinking on the dielectric relaxation has also been reported. POLYM. ENG. SCI., 47:984–995, 2007. © 2007 Society of Plastics Engineers
Effects of polymerization medium on electrical conductivity and optical properties of organic semiconductor‐based polypyrrole
Authors: Yakuphanoglu Fahrettin , Aydin Mehmet Enver 
Published: May 2007

AbstractThe effects of tetrabutylammonium tetrafluoroborate (TBAFB), tetrabutylammonium hexafluorophosphate (TBAPF6), and paratoluene sulfonoicacid (PTSA) polymerization mediums on the electrical conductivity and optical properties of the polypyrrole (PPy) have been investigated. The electrical conductivity and optical properties of the samples polymerized in presence of TBAFB, TBAPF6, and PTSA organic salts change with medium of prepared polymer. The electrical conductivity of the TBAFB, PTSA, and TBAPF6 samples at 27°C were found to be 3.43 × 10−1, 4.48 × 10−2, and 1.60 × 10−4 (S/cm), respectively. The lowest optical band gap of the polymer was found to be 2.23 eV. The refractive index dispersion of the samples obeys single oscillator model. The obtained results suggest that polymerization medium changes electrical conductivity and optical properties of the PPy. POLYM. ENG. SCI., 47:1016–1020, 2007. © 2007 Society of Plastics Engineers
Study of melt compounding conditions and characterization of polyamide 6/metallocene ethylene‐polypropylene‐diene copolymer/maleated ethylene‐polypropylene‐diene copolymer blends reinforced with layered silicates
Authors: García‐López D. , López‐Quintana S. , Gobernado‐Mitre I. , Merino J.C. , Pastor J.M. 
Published: May 2007

AbstractA low content of nanoclay (modified montmorillonite, MMT) was added to PA6/mEPDM/EPDM‐g‐MA blends via melt compounding in order to obtain three different nanoblends by two methods: (a) one‐step mixing in which the polymeric and the inorganic components were simultaneously introduced in the feed ports 1 and 2 of a corrotating twin‐screw extruder respectively; (b) two‐step mixing in which the PA6/mEPDM/EPDM‐g‐MA elastomeric blend was first obtained and in a second step the MMT was added at two different mixing speeds. The microscopic study and the mechanical characterization of the nanoblends showed a relationship between microstructure, processing conditions, and mechanical properties. A predominant reinforcement effect due to the presence of organoclays was observed. POLYM. ENG. SCI., 47:1033–1039, 2007. © 2007 Society of Plastics Engineers
Nonisothermal crystallization behavior and nucleation of LDPE/Al nano‐ and microcomposites
Authors: Huang Xingyi , Ke Qingquan , Kim Chonung , Zhong Hanfang , Wei Ping , Wang Genlin , Liu Fei , Jiang Pingkai 
Published: May 2007

AbstractThe nonisothermal crystallization and melting behavior of LDPE and LDPE/Al nano‐ and microcomposites prepared from melt compounding were studied using differential scanning calorimetry (DSC). The DSC results show that the Al nanoparticles can either facilitate or hinder the crystallization of LDPE, depending on the dispersion of the nanoparticles in LDPE. The well‐dispersed Al nanoparticles do not have nucleating effects and mainly act as obstacles in the crystallization process, but the agglomerates of Al nanoparticles can act as nucleating agents and slightly accelerate the crystallization process of LDPE. The Al microparticles have nucleating effect and facilitate the crystallization process of LDPE. The combined Avrami–Ozawa equation was used to describe the nonisothermal crystallization process. It was found that the combined Avrami–Ozawa method can successfully describe the nonisothermal crystallization process. The melting behavior indicates that the lamellar thickness distribution of the nanocomposites and microcomposites is not significantly changed in comparison with the neat LDPE. POLYM. ENG. SCI., 47:1052–1061, 2007. © 2007 Society of Plastics Engineers
High performance structured polymer barrier films obtained from compatibilized polypropylene/ethylene vinyl alcohol blends
Authors: Ait‐Kadi A. , Bousmina M. , Yousefi A.A. , Mighri F. 
Published: May 2007

AbstractThe effects of different functionalized polypropylene (PP) and diethyl maleate (DEM) combined with styrene–ethylene–butene–styrene copolymer (SEBS) on various properties of extruded‐stretched films of polypropylene/ethylene vinyl alcohol (PP/EVOH) blends were studied. The stretched films of the original PP/EVOH blends and those of the polymer‐g‐DEM modified blends showed lamellar‐type morphology, whereas their maleic anhydride (MAH) functionalized counterparts showed fibrillar morphology. Such peculiar morphology resulted in a dramatic decrease of oxygen permeability as compared with the unmodified or MAH modified PP/EVOH blends. These spectacular improvements in barrier properties were obtained without much altering thermal and mechanical properties of the blend. POLYM. ENG. SCI., 47:1114–1121, 2007. © 2007 Society of Plastics Engineers
Towards textile‐based fiber‐reinforced thermoplastic nanocomposites: Melt spun polypropylene‐montmorillonite nanocomposite fibers
Authors: Houphouët‐Boigny C. , Plummer C.J.G. , Wakeman M.D. , Månson J.‐A.E. 
Published: May 2007

AbstractThe present work is aimed at assessing the feasibility of integrating thermoplastic polypropylene nanocomposite matrices into conventional fiber‐reinforced composites based on hybrid textiles that incorporate both the matrix and glass‐fiber yarns, in order to reduce impregnation times. The focus is on the preparation and properties of the polypropylene nanocomposite fiber precursors and the implications for composite processing in general. However, preliminary results are also given that demonstrate satisfactory impregnation and consolidation of simple textiles produced byco‐weaving the nanocomposite yarns with glass‐fibers, given suitable processing conditions. POLYM. ENG. SCI., 47:1122–1132, 2007. © 2007 Society of Plastics Engineers