bluuebunny/crossref_metadata_2025_split huggingface dataset:
Single‐step nonlinear diffusion tensor estimation in the presence of microscopic and macroscopic motion
Authors: Aksoy Murat , Liu Chunlei , Moseley Michael E. , Bammer Roland 
Published: April 2008

AbstractPatient motion can cause serious artifacts in diffusion tensor imaging (DTI), diminishing the reliability of the estimated diffusion tensor information. Studies in this field have so far been limited mainly to the correction of miniscule physiological motion. In order to correct for gross patient motion it is not sufficient to correct for misregistration between successive shots; the change in the diffusion‐encoding direction must also be accounted for. This becomes particularly important for multishot sequences, whereby—in the presence of motion—each shot is encoded with a different diffusion weighting. In this study a general mathematical framework to correct for gross patient motion present in a multishot and multicoil DTI scan is presented. A signal model is presented that includes the effect of rotational and translational motion in the patient frame of reference. This model was used to create a nonlinear least‐squares formulation, from which the diffusion tensors were obtained using a nonlinear conjugate gradient algorithm. Applications to both phantom simulations and in vivo studies showed that in the case of gross motion the proposed algorithm performs superiorly compared to conventional methods used for tensor estimation. Magn Reson Med 59:1138–1150, 2008. © 2008 Wiley‐Liss, Inc.
3D RINEPT {1H}‐31P CSI: A feasible approach for the study of membrane turnover in the human brain
Authors: Wokrina Tim , Ulrich Marco , Weber‐Fahr Wolfgang , Ende Gabriele 
Published: April 2008

AbstractA fast, full 3D elliptical k‐space encoding phosphorous‐31 (31P) chemical shift imaging sequence, incorporating heteronuclear polarization transfer editing (RINEPT), was established. RINEPT literally requires simultaneous pulses at the frequencies of both the sensitive and the insensitive nuclei, but only a few MR imaging systems feature a second independent transmit channel. In this study, possible signal degradation of a sequential sequence design on systems featuring a single transmit channel was investigated with spin density matrix calculations and phantom measurements. In addition, metabolite signal intensities were determined in vivo as a function of echo and repetition times. The results enable optimization of the signal‐to‐noise ratio of one or more metabolites of interest. The results convincingly show that the optimized RINEPT sequence is useful in clinical routine 31PMRS protocols and provides spectra of excellent quality for the study of cell membrane phospholipid turnover in the human brain even at a low field strength of 1.5T. The 3D sequence design allows covering the whole brain in a single measurement, while scan times are compliant with clinical routine protocols. Magn Reson Med 59:999–1004, 2008. © 2008 Wiley‐Liss, Inc.
Uniform asymptotic Green's functions for efficient modeling of cracks in elastic layers with relative shear deformation controlled by linear springs
Authors: Peirce Anthony P. , Gu Hongren , Siebrits Eduard 
Published: April 2008

AbstractWe present a uniform asymptotic solution (UAS) for a displacement discontinuity (DD) that lies within the middle layer of a three‐layer elastic medium in which relative shear deformation between parallel interfaces is controlled by linear springs. The DD is assumed to be normal to the two interfaces between the elastic media. Using the Fourier transform method we construct a leading term in the asymptotic expansion for the spectral coefficient functions for a DD in a three‐layer‐spring medium. Although a closed‐form solution will require a solution in terms of an infinite series, we demonstrate how this UAS can be used to construct highly efficient and accurate solutions even in the case in which the DD actually touches the interface. We compare the results using the Green's function UAS solution for a crack crossing a soft interface with results obtained using a multi‐layer boundary element method. We also present results from an implementation of the UAS Green's function approach in a pseudo‐3D hydraulic fracturing simulator to analyze the effect of interface shear deformation on the fracture propagation process. These results are compared with field measurements. Copyright © 2008 John Wiley & Sons, Ltd.
A hypoplastic model for mechanical response of unsaturated soils
Authors: Mašín David , Khalili Nasser 
Published: April 2008

AbstractA new constitutive model is developed for the mechanical behaviour of unsaturated soils based on the theory of hypoplasticity and the effective stress principle. The governing constitutive relations are presented and their application is demonstrated using several experimental data from the literature. Attention is given to the stiffening effect of suction on the mechanical response of unsaturated soils and the phenomenon of wetting‐induced collapse. All model parameters have direct physical interpretation, procedures for their quantification from test data are highlighted. Quantitative predictions of the model are presented for wetting, drying and constant suction tests. Copyright © 2008 John Wiley & Sons, Ltd.
Explanation for micromorphologies around broken fibers in fiber‐reinforced composites
Authors: Li Hongzhou , Jia Yuxi , Luan Shifang , Xiang Qian , Han Charles C. , Mamtimin Geni , Han Yanchun , An Lijia 
Published: April 2008

AbstractExperimental observations on micromorphologies around broken fibers in glass‐fiber‐reinforced epoxy matrix composites reveal different kinds of highly oriented patches at the circumambience of broken fibers, whereas the bulk of the matrix has been observed to be largely isotropic. These patches are interpreted to correlated areas where the stress gradients of the matrix are formed after fiber breaking, but the underlying cause for the orientation is still unknown. The authors have modified an embedded cell model to explain the experimental phenomena. The finite element simulation indicates that the surfaces around broken fibers display a change from an extension micromorphology to a mixed tension and shear micromorphology with the increase of applied strain. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers
Hygrothermal degradation of the composite laminates from woven carbon/SC‐15 epoxy resin and woven glass/SC‐15 epoxy resin
Authors: Jana R.N. , Bhunia H. 
Published: April 2008

AbstractThe degradation mechanism for hygrothermal aging of woven carbon‐epoxy and woven glass‐epoxy composite laminates was investigated in the micro‐scale. Interlaminar shear and cross laminar flexural tests were performed on notched and unnotched specimens to know the mechanical performance of the composite laminates. The Interlaminar Shear Stress (ISS) for both the composites was also evaluated and correlated with the number of hygrothermal cycles. Four‐point bending and tensile or compression shear loading configurations were also used. The stress at the onset of delamination (Delamination Damage Tolerance, DDT) was identified from the load‐deflection curve of the flexural specimens and correlated with the number of hygrothermal cycles. It was found that both the ISS and DDT decrease with the exposure time. Dimensional stability was almost unchanged throughout the aging process, although there was a very little moisture absorption (∼1.3%) in glass‐epoxy and carbon‐epoxy composite laminates. SEM photomicrographs of the delaminated surface show that failure occurs suddenly in a macroscopically brittle mode by crack initiation and propagation method. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers.
Epoxy resin/plasticized carbon black composites. Part II. Correlation among network structure and mechanical properties
Authors: Abdel‐Aal N. , El‐Tantawy Farid , Al‐Hajry A. , Bououdina M. 
Published: April 2008

AbstractThe network structure, mechanical properties, and thermal gravimetric of epoxy resin filled with plasticized carbon black (CB) have been studied. The effect of CB concentration on composite morphology as well as cross linking density (n), volume fraction of resin (Vr), degree of crystallinity (Xc), mean gap among conductive particles (g), aspect ratio (F), and mechanical property such as modulus of elasticity (Ym), hardness (HA), and elongation at break (EB) have been examined and correlated to establish structure–property relationships. According to the thermal gravimetric analysis, the thermal decomposition of the composite took place at a slightly higher temperature than that of green epoxy. It proved that the inclusion of plasticized CB improves the quality of the network structure and enhances the mechanical properties of the composites. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers.
The safety of rosuvastatin in comparison with other statins in over 25 000 statin users in the Saskatchewan Health Databases
Authors: García‐Rodríguez Luis Alberto , González‐Pérez Antonio , Stang Mary Rose , Wallander Mari‐Ann , Johansson Saga 
Published: April 2008

AbstractPurposeTo compare mortality and the incidence of hospitalization for myopathy, rhabdomyolysis, acute renal failure and acute liver injury in patients receiving rosuvastatin and those taking other statins.MethodsPatients prescribed a statin that they had not used before were selected from the Saskatchewan Health Databases (SHD) and followed up from 1 July 2003 until 31 March 2005.ResultsWe studied 10 384 patients on rosuvastatin and 14 854 taking other statins. Two cases of myopathy were identified (one on rosuvastatin, one on another statin). The relative risk (RR) of myopathy in patients currently taking rosuvastatin compared with other statins was 1.31 (95% confidence interval [CI]: 0.13–13.41). Two cases of rhabdomyolysis were detected among current rosuvastatin users (incidence: 2.9 [95% CI: 0.8–10.7] per 10 000 person‐years). No cases of acute liver injury occurred among rosuvastatin patients. Seventeen cases of acute renal failure were identified (five among rosuvastatin users, 12 taking other statins). The RR of acute renal failure in current rosuvastatin users compared with other statins was 0.49 (95% CI: 0.16–1.50).We identified 285 deaths during the study period (87 among rosuvastatin users, 198 taking other statins). The RR of death in current rosuvastatin users compared with other statins was 0.42 (95% CI: 0.32–0.57).ConclusionsWe found no evidence that patients prescribed rosuvastatin were at greater risk of the study outcomes than patients prescribed other statins. There was no evidence of increased mortality among patients taking rosuvastatin, even after allowing for age, sex and prior statin use. Copyright © 2008 John Wiley & Sons, Ltd.
The safety of rosuvastatin in comparison with other statins in over 100 000 statin users in UK primary care
Authors: García‐Rodríguez Luis Alberto , Massó‐González Elvira Luján , Wallander Mari‐Ann , Johansson Saga 
Published: April 2008

AbstractPurposeTo compare mortality and the incidence of hospitalization for myopathy, rhabdomyolysis, acute renal failure and acute liver injury in patients receiving rosuvastatin and those taking other statins.MethodsPatients prescribed a statin that they had not used before were selected from the UK General Practice Research Database (GPRD) and followed up from 1 April 2003 to 31 December 2005.ResultsWe studied 10 289 patients on rosuvastatin and 117 102 taking other statins. No cases of myopathy, rhabdomyolysis or acute liver injury occurred among rosuvastatin users. In those taking statins other than rosuvastatin, the incidence of myopathy was 0.4 (95% confidence interval (CI): 0.1–0.9), of rhabdomyolysis was 0.4 (95%CI: 0.1–0.9) and of acute liver injury was 0.4 (95%CI: 0.2–1.0), per 10 000 person‐years. Fourteen cases of acute renal failure were identified (two among rosuvastatin users and 12 among other statin users). Among current users, the relative risk (RR) of acute renal failure in rosuvastatin users compared with other statin users was 1.16 (95%CI: 0.15–9.03).We identified 3232 deaths during the study period (173 in the rosuvastatin‐treated group and 3059 in the other statin group). The RR of death associated with current use of rosuvastatin compared with other statins was 0.55 (95%CI: 0.44–0.68).ConclusionsWe found no evidence that patients prescribed rosuvastatin were at greater risk of these outcomes than patients prescribed other statins. There was no evidence of increased mortality among patients taking rosuvastatin, even after allowing for age, sex and prior statin use. Copyright © 2008 John Wiley & Sons, Ltd.
A fluorescence approach of the gamma radiation effects on gramicidin A inserted in liposomes
Authors: Nae Maria , Gazdaru Doina , Acasandrei Adriana , Georgescu Rodica , Macri Beatrice Mihaela , Radu Mihai 
Published: April 2008

AbstractThe fluorescence of tryptophan residues of gramicidin A (gA), bound to phosphatidylcholine liposomes contains valuable information about local changes in the environment of the molecule induced by gamma radiation. With this work, we aim to demonstrate that the gamma radiation effect on the peptide involves the action of free radicals, derived from water radiolysis and the process of lipid peroxidation. Basically, the methodology consists of the analysis of UV and fluorescence emission spectra of the peptide liposome complexes under control conditions and upon gamma irradiation. Free radical production was impaired by the removal of molecular oxygen or the presence of ethanol in the liposome suspension. The intensity of the tryptophan fluorescence was recorded as a function of the gamma radiation dose in the range of 0–250 Gy and the data were fitted with a single decay exponential function containing an additional constant term (named residual fluorescence). The correlation between the decrease in tryptophan fluorescence emission (Dc = 80 ± 10 Gy) and increase in gamma radiation dose indicates the partial damage of the tryptophan side chains of gA. O2 removal or ethanol addition partially reduced the decay of the tryptophan fluorescence emission involving an indirect action of gamma radiation via a water radiolysis mechanism. The residual fluorescence emission (A0) increases in O2‐free buffer (98 ± 13) and in 10% ethanol‐containing buffer (74 ± 34) compared to control conditions (23 ± 5). Varying the dose rate between 1–10 Gy/min at a constant dose of 50 Gy, an inverse dose‐rate effect was observed. Thus, our study provides evidence for the lipid peroxidation effect on the tryptophan fluorescence. In conclusion, this article sustains the hypothesis of the connection between the lipid peroxidation and structural changes of membrane proteins induced by gamma radiation. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd.
A lactoferrin‐derived peptide with cationic residues concentrated in a region of its helical structure induces necrotic cell death in a leukemic cell line (HL‐60)
Authors: Onishi Junko , Roy Molay Kumar , Juneja Lekh Raj , Watanabe Yasuo , Tamai Youichi 
Published: April 2008

AbstractModel studies have shown that peptides derived from the N‐terminal region of bovine lactoferrin (Lf‐B) exhibit antitumor activity against certain cell lines. This activity is due primarily to the peptides' apoptogenic effect. Several reports indicate that cationic residues clustered in two regions of the peptide sequence can be shuffled into one region and thereby increase cytotoxic activity, although the mechanism of this enhanced cytotoxic effect has not been clarified. In this paper, we considered several parameters that determine the mode of cell death after exposure to a native Lf‐B derived peptide (Pep1, residues 17–34), and a modified peptide (mPep1) wherein the cationic residues of Pep1 are clustered in a single region of its helical structure. We found that the cytotoxic activity of mPep1 was about 9.6 fold‐higher than that of Pep1 against HL‐60 cells, as determined by the 3‐(4,5‐dimethylthiazol‐2‐yl)‐5(3‐carboxymethonyphenol)‐2‐(4‐sulfophenyl)‐2 H‐tetrazolium (MTS) assay. In investigating the expression of phosphatidylserine, we observed that the native peptide (Pep1) caused both apoptotic cell death and necrotic cell death, depending on the concentration of the peptide. In contrast, the action of mPep1 was exclusively characteristic of necrotic cell death. This observation was further confirmed by agarose gel electrophoresis, in which clear ladder‐like DNA bands were observed from cells exposed to Pep1, whereas DNA from cells treated with mPep1 produced a smeared pattern. We extended the study by investigating the release of mitochondrial cytochrome c into the cytosol, and the activation of caspase‐3; both peptides caused the release of cytochrome c into the cytosol, and the activation of caspase‐3.These results suggest that Pep1 may kill cancer cells by activating an apoptosis‐inducing pathway, whereas mPep1 causes necrotic cell death by destroying cellular membrane structure notwithstanding sharing some cellular events with apoptotic cell death. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd.
Cryogenic characteristics of sub‐100‐nm‐gate AlGaN/GaN MIS‐HEMTs
Authors: Endoh Akira , Watanabe Issei , Yamashita Yoshimi , Mimura Takashi , Matsui Toshiaki 
Published: April 2008

AbstractWe measured DC and RF characteristics at 300 and 16 K of sub‐100‐nm‐gate AlGaN/GaN metal‐insulator‐semiconductor (MIS) high electron mobility transistors (HEMTs) that had SiN/SiO2/SiN triple‐layer insulators. The drain‐source current and the maximum transconductance increased as expected. We observed an increase of 14 to 28% in the value of cutoff frequency fT at 16 K over that at 300 K. At 16 K, we obtained a maximum fT of 176 GHz at a gate length Lg of 45 nm. We estimated the average electron velocity under the gate by a transit time analysis. The average velocities were 2.2 × 107 cm/s at 300 K and 2.7 × 107 cm/s at 16 K. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electroluminescence characteristics of GaN HEMT at off‐state
Authors: Chen H. , Lai Z. , Kung S. , Penner R. , Li G. P. 
Published: April 2008

AbstractTwo types of light emission characteristics at the off‐state breakdown of GaN HEMTs were observed and investigated. One of them showed a yellow band electroluminescence characteristic at room temperature, which might be attributed to the same origin of yellow luminescence (YL) defects. The electric field dependence of this YL‐like light emission was found to be more sensitive than the other type. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Biexciton recombination in high quality GaN/AlGaN quantum wells
Authors: Stokker‐Cheregi F. , Vinattieri A. , Feltin E. , Simeonov D. , Carlin J.‐F. , Butté R. , Grandjean N. , Gurioli M. 
Published: April 2008

AbstractWe report on a clear experimental demonstration of the presence of biexciton recombination in high quality GaN/AlGaN quantum wells, thus opening the way to relevant improvements of the performances of GaN based devices. The samples have been grown by metalorganic vapor phase epitaxy optimizing the deposition conditions to strongly reduce the Al fluctuations in the barriers. This leads to a photoluminescence broadening of only 5 meV at a temperature of 10 K for an Al content in the barriers of 5%. The biexciton binding energy if found to be of the order of 9 meV. The recombination kinetics show that the exciton and biexciton components are not thermalized at low temperature allowing to extract the intrinsic lifetimes of the two components. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural and transport properties of InN grown on GaN by MBE
Authors: Wang Kejia (Albert) , Kosel Thomas , Jena Debdeep 
Published: April 2008

AbstractIn this work, the growth of InN on GaN substrates by molecular beam epitaxy and the structural and electrical characterization are presented. The quality of InN is found to be a sensitive function of the III/V flux ratio and the substrate temperature. The structural quality of InN is characterized by X‐ray diffraction, and the transport property is characterized by Hall effect measurements. An optimum growth window to obtain high structural quality InN with high electron mobility is observed. A strong correlation between the structural quality and the measured Hall mobility is shown. Transmission electron microscope study of InN shows high dislocation density (∼2 × 1011 cm–2 at 200 nm from the InN/GaN interface), which is the limiting factor for the transport property in InN. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical study of rare earth point defects in GaN
Authors: Sanna Simone , Hourahine B. , Frauenheim Th. , Gerstmann U. 
Published: April 2008

AbstractThe behavior of rare earth dopants in GaN was investigated by means of theoretical techniques. The Density Functional based Tight‐Binding method (DFTB) has been extended to include orbital dependent potentials (LDA+U and SIC‐like) in attempt to model the 4f states of lanthanide impurities within a realistic crystal model. We present results of an investigation into the structural and and energetic properties of rare earth (Eu, Er and Tm) point defects in GaN. Lanthanide ions (either isolated or complexed with GaN native defects) prefer the Ga‐site. Among the investigated defects the REGaVN pairs are the most promising candidates as luminescent centers, while interstitial lanthanides are found not to be compatible with the observed luminescence. Differences in the behavior of the single lanthanide ions are explained in terms of different 4f ‐shell occupation and ion size. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
How to optimize a CH cleavage with a mononuclear copper–dioxygen adduct?
Authors: De La Lande A. , Gérard H. , Parisel O. 
Published: April 2008

AbstractWe here report the investigations on the role of the charge transfer (CT) from copper toward dioxygen on the activation barrier of the CH bond breaking in a model [Cu(trenCH3)(O2)]+ adduct. By playing on the donating capability of the trenCH3 ligand, by means of a supplementary pseudopotential applied on the apical nitrogen atom, the existence of an optimum CT to achieve the rupture of the CH bond is revealed. When considering the dioxygen/superoxide/peroxide range in its whole, it appears that both dioxygen‐ and peroxide‐type complexes are poor oxidant toward the CH bond. At variance, superoxide dominant complexes are confirmed to be better suited for a reactive purpose. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Competitive coordination between lead and oligoelements with respect to some therapeutic heavy‐metal chelators
Authors: Gourlaouen C. , Parisel O. 
Published: April 2008

AbstractThe competitive complexation of Ca2+, Fe2+, Cu2+, Zn2+, and Pb2+ toward ethylene diamine tetraacetate (EDTA), dimercaprol and D‐penicillamine, three liganding agents commonly used in chelation therapy against heavy metal, especially lead, poisonings is examined by means of B3LYP calculations, natural population analyses, and the topological analysis of the electron localization function. It is shown that Pb2+ can displace any of Ca2+, Fe2+, Cu2+, or Zn2+ chelated by any of dimercaprol or D‐penicillamine, but can only displace Ca2+ if EDTA is concerned. The first two chelators thus appear as better entities than EDTA to be used in chelation therapy, where in vivo selective complexation is essential. Moreover, the comparison of the bonding characteristics of Pb2+ with those of the other cations allows deriving three features to be taken into account in designing new chelators expecting to have an increased selectivity toward this cation. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008