bluuebunny/crossref_metadata_2025 huggingface dataset:
Biomedical nanocomposites of poly(lactic acid) and calcium phosphate hybridized with modified carbon nanotubes for hard tissue implants
Authors: Lee Hae‐Hyoung , Sang Shin Ueon , Lee Jae‐Ho , Kim Hae‐Won
Published: May 2011

Degradable polymer‐based materials are attractive in orthopedics and dentistry as an alternative to metallic implants for use as bone fixatives. Herein, a degradable polymer poly(lactic acid) (PLA) was combined with novel hybrid nanopowder of carbon nanotubes (CNTs)‐calcium phosphate (CP) for this application. In particular, CNTs‐CP hybrid nanopowders (0.1 and 0.25% CNTs) were prepared from the solution of ionically modified CNTs (mCNTs), which was specifically synthesized to be well‐dispersed and thus to effectively adsorb onto the CP nanoparticles. The mCNTs‐CP hybrid nanopowders were then mixed with PLA (up to 50%) to produce mCNTs‐CP‐PLA nanocomposites. The mechanical tensile strength of the nanocomposites was significantly improved by the addition of mCNTs‐CP hybrid nanopowders. Moreover, nanocomposites containing low concentration of mCNTs (0.1%) showed significantly stimulated biological responses including cell proliferation and osteoblastic differentiation in terms of gene and protein expressions. Based on this study, the addition of novel mCNT‐CP hybrid nanopowders to PLA biopolymer may be considered a new material choice for developing hard tissue implants. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.
Giant magnetic moment of the core‐shell Co13@Mn20 clusters: First‐principles calculations
Authors: Jing Qun , Cao Hai‐Bin , Ge Gui‐Xian , Wang Yuan Xu , Yan Hong‐Xia , Zhang Zi‐Ying , Liu Yun‐Hu
Published: May 2011

The core‐shell clusters Co13@TM20 with TM = Mn, Fe, Co, and Ni are investigated within first‐principles simulations in the framework of density‐functional theory. Huge magnetic moments have been found in the Co13@TM20 clusters especially for the Co13@Mn20 cluster with a giant magnetic moment of 113 μB. The large magnetic moments are mainly due to the special core‐shell structure and the weak interaction between the TM and other atoms. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011
A new paradigm in molecular recognition? specific antibody binding to membrane‐inserted HIV‐1 epitopes
Authors: Nieva José L. , Apellaniz Beatriz , Huarte Nerea , Lorizate Maier
Published: May 2011

The conserved membrane proximal external region (MPER), adjacent to the transmembrane domain (TMD) of human immunodeficiency virus type‐1 (HIV‐1) gp41 glycoprotein subunit, is accessible to the broadly neutralizing 4E10 and 2F5 monoclonal antibodies (mAbs) and, therefore, constitutes a potential target for vaccine design. This gp41 domain is postulated to be functional during the Env glycoprotein‐mediated fusion reaction by destabilizing the highly rigid viral envelope. To perform this task, the aromatic‐rich MPER is believed to insert into the interfacial region of the viral membrane external monolayer, thereby inducing the restructuring of the lipid bilayer required for fusion–pore opening. This model predicts that: (i) 2F5 and 4E10 mAbs are capable of binding epitopes inserted into the membrane interface; (ii) in‐membrane binding will result in effective blocking of MPER membrane activity; and (iii) both processes, in‐membrane recognition and blocking of membrane activity, can be modulated by altering both the lipid composition and the MPER amino acid sequence. We review here recently reported experimental data consistent with those predictions, and further speculate on their relevance for prospective anti‐HIV vaccine development. Copyright © 2011 John Wiley & Sons, Ltd.
Mechanically enforced bond dissociation reports synergistic influence of Mn2+ and Mg2+ on the interaction between integrin α7β1 and invasin
Authors: Ligezowska Agnieszka , Boye Kristian , Eble Johannes A. , Hoffmann Bernd , Klösgen Beate , Merkel Rudolf
Published: May 2011

Integrins require the divalent ions magnesium and manganese for ligand recognition. Here we mechanically enforced bond dissociation to explore the influence of these ions on the mechanical strength of the specific bond between α7β1 integrin and its pathologically relevant ligand invasin. Upon addition of these cations to the measurement buffer, we observe a pronounced increase in the force necessary to separate integrin and invasin coated beads. Both ions were found to work synergistically. With free invasin in the measurement buffer we furthermore observe that competitive blocking of binding sites overrides the increase in binding strength of individual beads. We show that this is due to a very strong dependence of bond affinity on divalent ions. Our study illustrates the importance of divalent ions for the regulation of force transmission by integrin ligand bonds on the molecular level. Copyright © 2011 John Wiley & Sons, Ltd.
Characterization of hyaluronic acid interaction with calcium oxalate crystals: implication of crystals faces, pH and citrate
Authors: Lamontagne Charles‐Antoine , Plante Gérard E. , Grandbois Michel
Published: May 2011

Interaction between hyaluronic acid (HA) present at the surface of tubular epithelial cells and calcium oxalate monohydrate (COM) crystals is thought to play an important role in kidney stone formation. AFM‐based force spectroscopy, where HA is covalently attached to AFM‐probes, was used to quantify the interaction between HA and the surfaces of COM crystals. The work of adhesion of the HA‐probe as well as the rupture force of single HA molecules were quantified in order to understand the molecular regulation of HA binding to COM crystals. Our results reveal that HA adsorbs to the crystal surface in physiological conditions. We also observed increased adhesion when the pH is lowered to a value that increases the risk of kidney stone formation. HA adhesion to the COM crystal surface can be suppressed by citrate, a physiological inhibitor of stone retention currently used in the treatment and prevention of kidney stone formation. Interestingly, we also observed preferential binding of HA onto the [100] face versus the [010] face, suggesting a major contribution of the [100] faces in the crystal retention process at the surface of tubular epithelial cells and the promotion of stone formation. Our results clearly establish a direct role for the glycosaminoglycan HA present at the surface of kidney tubular epithelium in the process of COM crystal retention. Copyright © 2011 John Wiley & Sons, Ltd.
MRI Findings of recurrent hepatocellular carcinoma after liver transplantation: Preliminary results
Authors: Lee Chang Hee , Brubaker Lauren M. , Gerber David A. , Ku Young Mi , Kim Young Hoon , Shin Sang Soo , Semelka Richard C.
Published: May 2011

Purpose

To describe the patterns of recurrence and serial magnetic resonance imaging (MRI) features of hepatocellular carcinoma (HCC) after liver transplantation.

Materials and Methods

All cases of recurrent HCC after transplantation between September 2002 and August 2009 that underwent MRI including precontrast T1, T2‐weighted images, and postgadolinium dynamic images were reviewed. On MRI we evaluated the characteristics and patterns of recurrent HCC after transplantation.

Results

A total 7 of 76 transplanted patients (four men, three women, age range, 45–63, mean 52.7 years) were included in this study. Four patients (57.1%) were identified to have a pattern of persistent local disease (PLD) near the transplanted liver, hepatorenal space, or suture site within 2.75 years (range, 2–4 years). Two patients showed recurrent HCC in the allograft alone within 5 years. One patient showed an intraperitoneal seeding (IPS) pattern which demonstrated diffuse peritoneal infiltration and thickening within 9 months. The diffuse metastatic disease (DMD) pattern was observed as a late manifestation of PLD and IPS. The most prominent volume of recurrent tumor burden was found in an extrahepatic (5 of 7 patients) compared to an intrahepatic (2 of 7 patients) location. The signal intensities and enhancement patterns did not exhibit change with disease progression.

Conclusion

We describe four patterns of recurrence of HCC following transplant. The most prominent tumor burden was located in an extrahepatic compared to an intrahepatic location. J. Magn. Reson. Imaging 2011;33:1399–1405. © 2011 Wiley‐Liss, Inc.
Morphological manifestations of nonpuerperal mastitis on magnetic resonance imaging
Authors: Liu Haiquan , Peng Weijun
Published: May 2011

Purpose:

To investigate the morphological features of nonpuerperal mastitis on magnetic resonance imaging (MRI).

Materials and Methods:

MRI results of 27 patients diagnosed with nonpuerperal mastitis were retrospectively analyzed according to the Breast Imaging Reporting and Data System (BI‐RADS).

Results:

According to the enhanced MRI results, 22 cases presented as nonmass‐like enhancements and five cases presented as masses. For the 22 nonmass‐like enhancement lesions, one case showed as a homogeneous enhancement and 21 cases showed as heterogeneous enhancements. In the 21 heterogeneous enhancement cases, 13 contained lesions of rim‐like enhancement. With regard to the number of lesions with rim‐like enhancement, 11 presented as multiple and two as single. In the five mass lesions, three presented as rim enhancements. Indications of rim or rim‐like enhancement accounted for 59% (16/27) of all cases. For the 16 cases that presented with signs of rim or rim‐like enhancement, the central hypointensity area surrounded by enhanced rim or rim‐like entity showed as hyperintensity in 14 cases and hypointensity or heterointensity in two cases on T2‐weighted imaging.

Conclusion:

On contrast‐enhanced MRI, most nonpuerperal mastitis presented as nonmass‐like lesion with heterogeneous signal intensity. The observation of signs of rim or rim‐like enhancement on contrast‐enhanced MRI with central hypointensity areas showing as hyperintensity on T2‐weighted imaging is suggestive of the possibility of nonpuerperal mastitis. J. Magn. Reson. Imaging 2011;33:1369–1374. © 2011 Wiley‐Liss, Inc.
Fast Lipid And Water Levels by Extraction with Spatial Smoothing (FLAWLESS): Three‐dimensional volume fat/water separation at 7 Tesla
Authors: Narayan Sreenath , Huang Fangping , Johnson David , Gargesha Madhusudhana , Flask Chris A. , Zhang Guo‐Qiang , Wilson David L.
Published: May 2011

Purpose:

To quickly and robustly separate fat/water components of 7T MR images in the presence of field inhomogeneity for the study of metabolic disorders in small animals.

Materials and Methods:

Starting with a Markov random field (MRF) based formulation for the 3‐point Dixon separation problem, we incorporated new implementation strategies, including stability tracking, multiresolution image pyramid, and improved initial value generation. We term the new method FLAWLESS (Fast Lipid And Water Levels by Extraction with Spatial Smoothing).

Results:

Compared with non‐MRF techniques, FLAWLESS decreased the fat–water swapping mistakes in all of the three‐dimensional (3D) animal volumes that we tested. FLAWLESS converged in approximately 1/60th of the computation time of other MRF approaches. The initial value generation of FLAWLESS further improved robustness to field inhomogeneity in 3D volume data.

Conclusion:

We have developed a novel 3‐point Dixon technique found to be useful for high field small animal imaging. It is being used to assess lipid depots and metabolic disorders as a function of genes, diet, age, and therapy. J. Magn. Reson. Imaging 2011;33:1464–1473. © 2011 Wiley‐Liss, Inc.
Breast diffusion‐weighted MRI: Comparison of tetrahedral versus orthogonal diffusion sensitization for detection and localization of mass lesions
Authors: Ueguchi Takashi , Yamada Sachiko , Mihara Naoki , Koyama Yoshihiro , Sumikawa Hiromitsu , Tomiyama Noriyuki
Published: May 2011

Purpose:

To evaluate the potential of tetrahedral diffusion‐weighted imaging (DWI) compared to orthogonal DWI for detection and localization of early enhanced breast mass lesions at 1.5T.

Materials and Methods:

Sixty‐seven consecutive patients (mean age 51.7 years, range 14–84 years) with 68 solitary early enhanced breast lesions suspicious for cancer on dynamic contrast‐enhanced magnetic resonance imaging (MRI) were enrolled in this retrospective study. Two radiologists independently observed maximum intensity projection images of orthogonal and tetrahedral DWI and the diagnostic accuracy and background tissue visibility between two DWI techniques were compared. Contrast‐enhanced MRI was used as the reference standard. Background tissue visibility was assessed based on whether the “breast quadrant” and “skin line” were determined. A phantom validation study for apparent diffusion coefficient (ADC) values was also conducted.

Results:

Sensitivity (93%) and specificity (96%) on tetrahedral DWI were equivalent to those on orthogonal DWI (sensitivity, 88%; specificity, 95%). Background tissue was more easily determined with tetrahedral DWI (breast quadrant, 90%; skin lines, 95%) than with orthogonal DWI (breast quadrant, 61%; skin lines, 16%). ADC values of tetrahedral DWI were highly correlated with those of orthogonal DWI.

Conclusion:

Tetrahedral DWI provided equivalent detectability of mass lesions with improved visibility of surrounding anatomical structure. J. Magn. Reson. Imaging 2011;33:1375–1381. © 2011 Wiley‐Liss, Inc.
Noncontrast MR angiography for comprehensive assessment of abdominopelvic arteries using quadruple inversion‐recovery preconditioning and 3D balanced steady‐state free precession imaging
Authors: Atanasova Iliyana P. , Kim Daniel , Lim Ruth P. , Storey Pippa , Kim Sooah , Guo Hua , Lee Vivian S.
Published: May 2011

Purpose:

To develop a noncontrast magnetic resonance angiography (MRA) method for comprehensive evaluation of abdominopelvic arteries in a single 3D acquisition.

Materials and Methods:

A noncontrast MRA (NC MRA) pulse sequence was developed using four inversion‐recovery (IR) pulses and 3D balanced steady‐state free precession (b‐SSFP) readout to provide arterial imaging from renal to external iliac arteries. Respiratory triggered, high spatial resolution (1.3 × 1.3 × 1.7 mm3) noncontrast angiograms were obtained in seven volunteers and ten patients referred for gadolinium‐enhanced MRA (CE MRA). Images were assessed for diagnostic quality by two radiologists. Quantitative measurements of arterial signal contrast were also performed.

Results:

NC MRA imaging was successfully completed in all subjects in 7.0 ± 2.3 minutes. In controls, image quality of NC MRA averaged 2.79 ± 0.39 on a scale of 0–3, where 3 is maximum. Image quality of NC MRA (2.65 ± 0.41) was comparable to that of CE MRA (2.9 ± 0.32) in all patients. Contrast ratio measurements in patients demonstrated that NC MRA provides arterial contrast comparable to source CE MRA images with adequate venous and excellent background tissue suppression.

Conclusion:

The proposed noncontrast MRA pulse sequence provides high‐quality visualization of abdominopelvic arteries within clinically feasible scan times. J. Magn. Reson. Imaging 2011;33:1430–1439. © 2011 Wiley‐Liss, Inc.
Dual‐temporal resolution dynamic contrast‐enhanced MRI protocol for blood–brain barrier permeability measurement in enhancing multiple sclerosis lesions
Authors: Jelescu I.O. , Leppert I.R. , Narayanan S. , Araújo D. , Arnold D.L. , Pike G.B.
Published: May 2011

Purpose:

To design a more accurate and reproducible technique for the measurement of blood–brain barrier (BBB) permeability in gadolinium‐enhancing multiple sclerosis (MS) lesions.

Materials and Methods:

Four MS patients were scanned using a new dynamic contrast‐enhanced (DCE)‐magnetic resonance imaging (MRI) protocol based on an uninterrupted two‐part acquisition consisting of an initial part at high temporal and low spatial resolutions and a second part at low temporal and high spatial resolutions. The method preserves both the high spatial resolution needed for the often small size of lesions and the high temporal resolution required during the first minute after injection to sufficiently sample the first‐pass bolus. Simulations compared the performance of this new protocol with the conventional one at low temporal and high spatial resolutions throughout.

Results:

The BBB permeability estimates changed by up to 33% between the two protocols. The new protocol led to simulated error on Ktrans of 7%–10%, versus 7%–30% with the conventional protocol, and was more robust with respect to offsets between acquisition and injection start times, differences in shape of the first‐pass peak, and permeability values.

Conclusion:

The dual‐temporal resolution protocol produces improved BBB permeability estimates and provides a more complete view of active inflammatory MS lesion pathology. J. Magn. Reson. Imaging 2011;33:1291–1300. © 2011 Wiley‐Liss, Inc.
Measurement of aortic arch pulse wave velocity in cardiovascular MR: Comparison of transit time estimators and description of a new approach
Authors: Dogui Anas , Redheuil Alban , Lefort Muriel , DeCesare Alain , Kachenoura Nadjia , Herment Alain , Mousseaux Elie
Published: May 2011

Purpose:

To investigate the efficiency of a new method (TT‐Upslope) for transit time (Δt) estimation from cardiovascular MR (CMR) velocity curves.

Materials and Methods:

Fifty healthy volunteers (40 ± 15 years) underwent applanation tonometry to estimate carotid–femoral pulse wave velocity (cf‐PWV) and carotid pressure measurements, and CMR to estimate aortic arch‐PWV and ascending aorta distensibility (AAD). The Δt was calculated with TT‐Upslope by minimizing the area delimited by two sigmoid curves fitted to the systolic upslope of the ascending (AAC) and descending (DAC) aorta velocity curves, and compared with previously described methods: TT‐Point using the half maximum of AAC and DAC, TT‐Foot using AAC and DAC feet, and TT‐Wave by minimizing the area between AAC and DAC curves using cross correlation.

Results:

All the Δt methods provided a high reproducibility of arch‐PWV. However, TT‐Upslope and TT‐Wave resulted in better correlations with aging (r = 0.83/r = 0.83 versus r = 0.47/r = 0.72), cf‐PWV (r = 0.69/r = 0.70 versus r = 0.34/r = 0.59), and AAD (r = 0.81/r = 0.71 versus r = 0.61/r = 0.60). Furthermore, TT‐Upslope resulted in stronger relationship between arch‐PWV and AAD according to a theoretical model and provided better characterization of older subjects compared with TT‐Wave.

Conclusion:

Arch‐PWV estimated with CMR using the TT‐Upslope method was found to be reproducible and accurate, providing strong correlations with age and aortic stiffness indices. J. Magn. Reson. Imaging 2011;33:1321–1329. © 2011 Wiley‐Liss, Inc.
Cardiovascular MR dobutamine stress in adult tetralogy of fallot: Disparity between CMR volumetry and flow for cardiovascular function
Authors: Valverde Israel , Parish Victoria , Tzifa Aphrodite , Head Catherine , Sarikouch Samir , Greil Gerald , Schaeffter Tobias , Razavi Reza , Beerbaum Philipp
Published: May 2011

Purpose:

To evaluate the MR agreement of cardiac function parameters between volumetric (cine SSFP) and phase contrast flow (PC‐flow) assessment in patients with repaired tetralogy of Fallot (r‐TOF) and chronic pulmonary regurgitation (PR) at rest and under dobutamine stress (DS‐MR).

Materials and Methods:

We studied 18 patients with r‐TOF and severe chronic PR (34 ± 12.7 years, PR fraction[flow] 44 ± 15%) by cardiac MR at rest, 10 and 20 μg/kg/min of dobutamine. We compared analogous functional parameters by volumetry and PC‐flow: (i) Systemic output [left ventricle stroke volume (LVSV) versus aortic forward flow (AOFF)], (ii) Pulmonary output [right ventricle stroke volume (RVSV) versus pulmonary forward flow (PAFF)], (iii) PR volume [(RVSV‐LVSV) versus pulmonary backward flow (PABF)], (iv) PR fraction [(RVSV‐LVSV/RVSV) versus (PABF/PAFF)].

Results:

We found excellent Bland‐Altman agreement (mean difference ± limits of agreement, mL/beat/m2) at rest for both the systemic (−0.8 ± 5.7) and pulmonary strokes volumes (−0.1 ± 7.6), which slightly deteriorates during DS‐MR. The PR volume showed acceptable agreement at rest (−3.6 ± 15.1), but also further deteriorated during stress (5.4 ± 24). In contrast, the PR fraction showed poor agreement equally at rest (−5.6 ± 22.8) and DS‐MR (3.2 ± 19.2).

Conclusion:

In r‐TOF with chronic PR, analogous functional parameters should not be used interchangeably between volumetric and PC‐flow assessment during DS‐MR evaluation. J. Magn. Reson. Imaging 2011;33:1341–1350. © 2011 Wiley‐Liss, Inc.
Quantitative assessment of the cervical spinal cord damage in neuromyelitis optica using diffusion tensor imaging at 3 Tesla
Authors: Qian Wenshu , Chan Queenie , Mak Henry , Zhang Zhongping , Anthony Marina‐Portia , Yau Kelvin Kai‐Wing , Khong Pek‐Lan , Chan Koon Ho , Kim Mina
Published: May 2011

Purpose:

To investigate whether quantitative MRI measures of cervical spinal cord white matter (WM) using diffusion tensor imaging (DTI) in neuromyelitis optica (NMO) differed from controls and correlated with clinical disability.

Materials and Methods:

Ten referred patients and 12 healthy volunteers were imaged on a 3 Tesla scanner and patients were clinically assessed on the Expanded Disability Status Scale (EDSS). Two raters quantified DTI‐derived indices from all participants, including fractional anisotropy (FA), mean diffusivity (MD), parallel diffusivity (lambda[parallel]) and perpendicular diffusivity (lambda[perpendicular]) at C1–C6 for lateral and dorsal columns. After the inter‐rater reliability test, univariate correlations between DTI measures and disability were assessed using the Spearman's rho correlation coefficient. Multiple regression analysis was performed to investigate which DTI measures independently correlated with the clinical score.

Results:

Statistical test results indicated high reliability of all DTI measurements between two raters. NMO patients showed reduced FA, increased MD and lambda[perpendicular] compared with controls while lambda[parallel] did not show any significant difference. The former three DTI metrics also showed significant correlations with disability scores, and especially FA was found to be sensitive to mild NMO (EDSS ≤ 3)

Conclusion:

FA is a potentially useful quantitative biomarker of otherwise normal appearing WM damage in NMO. Such damage is associated with clinical disability. J. Magn. Reson. Imaging 2011;33:1312–1320. © 2011 Wiley‐Liss, Inc.
Early onset of retrograde flow in the main pulmonary artery is a characteristic of pulmonary arterial hypertension
Authors: Helderman Frank , Mauritz Gert‐Jan , Andringa Kirsten E. , Vonk‐Noordegraaf Anton , Marcus J. Tim
Published: May 2011

Purpose:

To evaluate if early onset of retrograde flow in the main pulmonary artery is a characteristic of pulmonary arterial hypertension (PAH).

Materials and Methods:

Fifty‐five patients with suspected pulmonary hypertension (PH) underwent right‐sided heart catheterization and retrospectively ECG‐gated MR phase‐contrast velocity quantification in the main pulmonary artery. Pulmonary hypertension was defined by a mean pulmonary artery pressure being larger than 25 mmHg. The onset time of the retrograde flow relative to the cardiac cycle duration (Relative Onset Time = ROT) was compared with mean pulmonary artery pressure.

Results:

By the catheterization, 38 patients were identified as having PAH. The ROT for these PAH patients was significantly different from those found in the 17 non‐PH subjects (0.14 ± 0.06 versus 0.37 ± 0.06, P < 0.001). The mean pulmonary artery pressure was related to the ROT (r2 = 0.62, P < 0.001) and could be estimated from the ROT with a standard deviation of 11.7 mmHg. With a cutoff value of 0.25, the ROT distinguished PAH patients from non‐PH subjects.

Conclusion:

Early onset of retrograde flow in the main pulmonary artery is a characteristic of pulmonary arterial hypertension and is visible by standard MR phase‐contrast velocity quantification. J. Magn. Reson. Imaging 2011;33:1362–1368. © 2011 Wiley‐Liss, Inc.
Hepatic fat quantification using chemical shift MR imaging and MR spectroscopy in the presence of hepatic iron deposition: Validation in phantoms and in patients with chronic liver disease
Authors: Lee Seung Soo , Lee Youngjoo , Kim Namkug , Kim Seong Who , Byun Jae Ho , Park Seong Ho , Lee Moon‐Gyu , Ha Hyun Kwon
Published: May 2011

Purpose:

To compare the accuracy of four chemical shift magnetic resonance imaging (MRI) (CS‐MRI) analysis methods and MR spectroscopy (MRS) with and without T2‐correction in fat quantification in the presence of excess iron.

Materials and Methods:

CS‐MRI with six opposed‐ and in‐phase acquisitions and MRS with five‐echo acquisitions (TEs of 20, 30, 40, 50, 60 msec) were performed at 1.5 T on phantoms containing various fat fractions (FFs), on phantoms containing various iron concentrations, and in 18 patients with chronic liver disease. For CS‐MRI, FFs were estimated with the dual‐echo method, with two T2*‐correction methods (triple‐ and multiecho), and with multiinterference methods that corrected for both T2* and spectral interference effects. For MRS, FF was estimated without T2‐correction (single‐echo MRS) and with T2‐correction (multiecho MRS).

Results:

In the phantoms, T2*‐ or T2‐correction methods for CS‐MRI and MRS provided unbiased estimations of FFs (mean bias, −1.1% to 0.5%) regardless of iron concentration, whereas the dual‐echo method (−5.5% to −8.4%) and single‐echo MRS (12.1% to 37.3%) resulted in large biases in FFs. In patients, the FFs estimated with triple‐echo (R = 0.98), multiecho (R = 0.99), and multiinterference (R = 0.99) methods had stronger correlations with multiecho MRS FFs than with the dual‐echo method (R = 0.86; P ≤ 0.011). The FFs estimated with multiinterference method showed the closest agreement with multiecho MRS FFs (the 95% limit‐of‐agreement, −0.2 ± 1.1).

Conclusion:

T2*‐ or T2‐correction methods are effective in correcting the confounding effects of iron, enabling an accurate fat quantification throughout a wide range of iron concentrations. Spectral modeling of fat may further improve the accuracy of CS‐MRI in fat quantification. J. Magn. Reson. Imaging 2011;33:1390–1398. © 2011 Wiley‐Liss, Inc.
Future changes in intense precipitation over Canada assessed from multi‐model NARCCAP ensemble simulations
Authors: Mailhot Alain , Beauregard Ian , Talbot Guillaume , Caya Daniel , Biner Sébastien
Published: May 2011

Annual maxima (AM) series of precipitation from 15 simulations of the North American Regional Climate Change Assessment Program (NARCCAP) have been analysed for gridpoints covering Canada and the northern part of United States. The NARCCAP Regional Climate Models' simulations have been classified into the following three groups based on the driving data used at the RCMs boundaries: (1) NCEP (6 simulations); (2) GCM‐historical (5 simulations); and (3) GCM‐future (4 simulations). Historical simulations are representative of the 1968‐2000 period while future simulations cover the 2041‐2070 period. A reference common grid has been defined to ease the comparison. Multi‐model average intensities of AM precipitation of 6‐, 12‐, 24‐, 72‐, and 120‐h for 2‐, 5‐, 10‐, and 20‐year return periods have been estimated for each simulation group. Comparison of results from NCEP and GCM‐historical groups shows good overall agreement in terms of spatial distribution of AM intensities. Comparison of GCM‐future and GCM‐historical groups clearly shows widespread increases with median relative changes across all gridpoints ranging from 12 to 18% depending on durations and return periods. Fourteen Canadian climatic regions have been used to define regional projections and average regional changes in intense precipitation have been estimated for each duration and return period. Uncertainties on these regional values, resulting from inter‐model variability, were also estimated. Results suggest that inland regions (e.g. Ontario and more specifically Southern Ontario, the Prairies, Southern Quebec) will experience the largest relative increases in AM intensities while coastal regions (e.g. Atlantic Provinces and the West Coast) will experience the smallest ones. These projections are most valuable inputs for the assessment of future impact of climate change on water infrastructures and the development of more efficient adaptation strategies. Copyright © 2011 Royal Meteorological Society
A statistical model for the urban heat island and its application to a climate change scenario
Authors: Hoffmann Peter , Krueger Oliver , Schlünzen K. Heinke
Published: May 2011

A linear statistical model relating the nocturnal urban heat island (UHI) intensity of Hamburg with meteorological conditions is constructed from observations taken by the German Meteorological Service (DWD). To find the appropriate predictors the relationship between different meteorological variables and the UHI of Hamburg is analyzed. Results and physical plausibility suggest that cloud cover, wind speed and relative humidity are the relevant variables and can be used to construct a statistical model. The parameters for the statistical model are determined with the generalized least square method. With the help of the statistical model up to 42% of the UHI variance can be explained. The statistical model is then used to statistically downscale results from climate runs of the regional climate models (RCM) REMO and CLM. Both RCMs were driven with the A1B SRES emission scenario runs of the global climate model ECHAM5/MPI‐OM. The resulting values for the future UHI are analyzed with respect to monthly averages and the frequency distribution. Results show that changes in the UHI are different for the different months. Significant change (decrease of UHI) in the results of both RCMs and for both realizations of the A1B scenario can be found for April in at the middle and the end of the century and in December at the end of the century. For the summer months which are most relevant to the development of adaption strategies the results differ between the RCMs. REMO results show no significant changes for the summer, while analyses of CLM suggest significant increase in July and August. The frequency distribution of the summer UHI shows no significant changes for REMO and only in one realization of CLM a significant increase in moderate and strong UHI days can be found for the end of the century. Copyright © 2011 Royal Meteorological Society
Classification of precipitation series using fuzzy cluster method
Authors: Dikbas Fatih , Firat Mahmut , Koc A. Cem , Gungor Mahmud
Published: May 2011

The identification of hydrologically homogeneous regions is one of the most important steps of regional frequency analysis. The hydrologically homogeneous regions should be determined using cluster analysis instead of the geographically close regions or stations. In this study, fuzzy cluster method (Fuzzy C‐Means: FCM) is applied to classify the precipitation series and identify the hydrologically homogeneous groups. The choice of appropriate cluster method and the variables that will be used according to the data of the basin is also very important. In the context of this study, total precipitation data of stations operated by National Meteorology Works (DMI) in Turkish basins for cluster analysis are used. The optimal number of groups is determined as six, based on different performance evaluation indexes. Regional homogeneity tests based on L‐moments method are applied to check homogeneity of these six regions identified by cluster analysis. Regional homogeneity test results show that regions defined by FCM method are sufficiently homogeneous for regional frequency analysis. According to the results, FCM method is recommended for classifying the precipitation series and for identifying the hydrologically homogenous regions. Copyright © 2011 Royal Meteorological Society
Relationship of summer soil moisture with early winter monsoon and air temperature over eastern China
Authors: Liu Ge , Chen Jun‐Ming , Ji Li‐Ren , Sun Shu‐Qing
Published: May 2011

The time‐lagged effect of summer soil moisture (SM) on ensuing winter climate in eastern China is examined. The East Asian winter monsoon (EAWM) in early winter (November) and associated air temperature over eastern China are shown to significantly correlate with the previous summer (June–August) SM in eastern China with a center located at the lower reaches of the Yellow River (LRYR). The positive anomalies of summer SM, persisting for a few months, may act as a buffer to defer the ground cooling of eastern China in early winter mainly through modulating thermal capacity. And the warmer ground of eastern China could lead to a warmer air temperature above the ground through direct land–air interactions and through indirectly adjusting the EAWM which is sensitive to the land–sea thermal contrast. These results provide an empirical predictor for the EAWM and for the variability of air temperature over eastern China in early winter. Copyright © 2011 Royal Meteorological Society
Characterising the long‐range transport mechanisms of different aerosol types over Athens, Greece during 2000–2005
Authors: Kaskaoutis D. G. , Nastos P. T. , Kosmopoulos P. G. , Kambezidis H. D.
Published: May 2011

This study analyses the weather conditions, the main pathways and transport mechanisms favouring the presence of specific aerosol types over Athens, Greece. On the basis of the aerosol optical depth at 550 nm (AOD550) and fine mode (FM) values from a Terra‐MODIS dataset in the period 2000–2005, three main aerosol types are identified (urban/industrial, UI; clean maritime, CM; and desert dust, DD), each one corresponding to different optical characteristics and source regions. The UI aerosols are associated with polluted air masses from Europe, the CM aerosols with clean Atlantic air masses and the DD aerosols with air masses from North African arid regions carrying significant amount of dust in certain cases. The comparison of the three aerosol types with the air masses from their favourable sector constitutes a first ‘quick‐validation’ of the identification scheme. Thus, the incidence of transport from Europe explain 81% of the variability in the observed UI type, while the 73% of the Atlantic air masses correspond to the CM type; the 50% of the African air masses can be considered as DD aerosols over Athens. The mean synoptic meteorological patterns, favouring the presence of each aerosol type, are also investigated. Further analysing the air‐mass trajectories at three altitudes, the transport mechanisms of the aerosol types are identified. The results clearly show that the UI aerosols are mainly transported within the boundary layer, while the CM conditions are associated with Atlantic air masses at higher altitudes. Moreover, the DD aerosols are transported either in the upper atmosphere or in the whole atmospheric column. This is among the first studies conducted over Athens aiming at investigating the weather conditions, pathways and transport mechanisms that favour the presence of aerosols of different characteristics. Copyright © 2011 Royal Meteorological Society
Characterization of typical coastal circulations with high‐resolution measurements in the Gulf of Valencia
Authors: Fock Björn Hendrik , Schlünzen K. Heinke
Published: May 2011

Measurements from 27 stations taken in the coastal area of the Gulf of Valencia are utilized to characterize the typical coastal circulation systems observed in this area. The wind measurements are available in a resolution of 15 s at daytime and 5 min at nighttime and cover the period of May 2006–April 2007. The analysis of median daily cycles shows that the meteorological situation in the Gulf of Valencia is dominated by a distinguished sea breeze. The observed development of local circulation systems varies within a distance of just a few kilometres, not only over land but also over water. These variations can be explained by the local influences of a pronounced coastal orography, land use and shape of the coastline. The measurements are classified in days with and days without pronounced sea breeze effects. This classification allows a refined discussion on spatial and temporal characteristics of the observed circulation systems. The classification shows an occurrence of sea breezes at 2 out of 3 days. Copyright © 2011 Royal Meteorological Society
Divergent views of venture capitalists and entrepreneurs on strategic change in new ventures
Authors: Gimmon Eli , Yitshaki Ronit , Benjamin Eyal , Khavul Susanna
Published: May 2011

The inherent conflicts between venture capital investors and entrepreneurs are reflected in perception of trust and causes for strategic reorientation.
The effects of ‘blockholders’ on the value of companies listed in the Tehran stock exchange
Authors: Shourvarzi Mohammad Reza , Hamidi Mojgan
Published: May 2011

An increase in the number of blockholders can help improve the market value of listed companies.
Polymeric ionic liquid‐coated capillary for capillary electrophoresis
Authors: Li Jing , Han Haifeng , Wang Qing , Liu Xia , Jiang Shengxiang
Published: May 2011

A new application of the polymeric ionic liquid (PIL) in capillary electrophoresis is reported. Poly(1‐vinyl‐3‐butylimidazolium bromide) was physically adsorbed on silica capillary as the simple and effective coating for capillary electrophoresis (CE) analysis, in which the PIL is not present in the background electrolyte. The electroosmotic flow (EOF) of the PIL‐coated capillary as compared with that of the bare fused‐silica capillary shows a different dependence on electrolyte pH values. The EOF is reversed over a wide pH range from 3.0 to 9.0 and shows good repeatability. It is also found that the coated capillary has a good tolerance to some organic solvents, 0.1 M NaOH and 0.1 M HCl. The PIL‐coated capillary has been employed in different areas. Both the basic proteins and anionic analytes can be well separated by PIL‐coated capillaries in a fast and easy way. The PIL‐coated capillary is also able to separate organic acid additives in a grape juice. The results showed that this type of coating provides an alternative to the CE separation of anions and basic proteins.
EXCLOSURE EFFECTS ON RECOVERY OF SELECTED SOIL PROPERTIES IN A MIXED BROADLEAF FOREST RECREATION SITE
Authors: Özcan M. , GÖkbulak F. , Hizal A.
Published: May 2011

Human‐caused trampling that results from excessive recreational use has caused damage to soil and vegetation in forest ecosystems in the Belgrad Forest of Istanbul. The objectives of this study were to examine effects of exclosure on selected soil properties and to determine the recovery time required for soil characteristics in a broadleaf forest recreation site.

Litter biomass and topsoil (0–15 cm) were sampled in the forest, exclosure and recreational sites, and soil samples were analysed for saturation capacity, permeability, bulk density, total porosity, organic matter, root biomass, electrical conductivity and soil pH.

Results showed that saturation capacity, permeability, total porosity and organic matter increased whereas bulk density decreased significantly in the topsoil under the exclosure, and all these soil properties in the topsoil of the exclosure were greater than those of recreational site. When effects of main factors were compared, averaging over sampling year and soil sampling depth, soils from the exclosure had significantly greater saturation capacity, permeability, total porosity, organic matter and litter biomass and lower bulk density values than the soils from recreational site.

Six years of exclosure was effective in improving most of the soil properties in the topsoil. When topsoil and subsoil are considered together, it is obvious that a longer time period is needed for soil recovery in the forest recreational sites. Copyright © 2011 John Wiley & Sons, Ltd.
Nitrogen‐Rich Plasma‐Polymerized Coatings on PET and PTFE Surfaces Improve Endothelial Cell Attachment and Resistance to Shear Flow
Authors: Gigout Anne , Ruiz Juan‐Carlos , Wertheimer Michael R. , Jolicoeur Mario , Lerouge Sophie
Published: May 2011

Low seeding efficiency and poor cell retention under flow‐induced shear stress limit the effectiveness of in vitro endothelialization strategies for small‐diameter vascular grafts. Primary‐amine‐rich plasma‐polymerized coatings (PPE:N) deposited using low‐ and atmospheric‐pressure plasma discharges on PET and PTFE are evaluated for their ability to improve endothelial cells' kinetics and strength of attachment. PPE:N coatings increase cell adhesion and adhesion rate, spreading, focal adhesion, and resistance to flow‐induced shear compared with bare and gelatin‐coated PET and PTFE. In particular, about 90% of the cells remain on coated surfaces after 1 h exposure to shear. These coatings, therefore, appear as a promising versatile approach to improve cell seeding strategies for vascular grafts.

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Hybrid Coatings Containing Silver Nanoparticles Generated In situ in a Thiol‐Ene Photocurable System
Authors: Colucci Giovanna , Celasco Edvige , Mollea Chiara , Bosco Francesca , Conzatti Lucia , Sangermano Marco
Published: May 2011

Novel silver/polymer composites based on thiol‐ene chemistry are prepared by an in situ bottom‐up approach. The in situ synthesis of silver particles inside the polymer matrix is achieved in one pot by photoreduction reaction in presence of a silver precursor and the concurrent crosslinking reaction. XPS analysis confirms the formation of silver particles; TEM morphological investigation shows a very good dispersion and distribution of the nanometric silver particles within the thiol‐ene network. Antimicrobial properties of the photocured hybrids are also evaluated.

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Morphology and Properties of Polymer Composites Based on Biodegradable Polylactide/Poly[(butylene succinate)‐co‐adipate] Blend and Nanoclay
Authors: Ojijo Vincent , Cele Hastings , Sinha Ray Suprakas
Published: May 2011

Polymer composites based on biodegradable polylactide/poly[(butylene succinate)‐co‐adipate] (PLA/PBSA) blend and pristine and organically modified clays have been prepared via melt‐mixing in a batch‐mixer. Four different surfactants have been used to modify the pristine montmorillonite (MMT) clay. The weight ratio of the PLA and PBSA is 70:30, while the weight of the MMT is fixed at 6%. The surface morphologies of the unmodified and organoclay‐modified blends have been studied by field‐emission scanning electron microscopy. Results show that the domain size of the dispersed PBSA‐phase is reduced with the addition of organoclay and the extent of this reduction in the size of PBSA domain is dependent on not only the interlayer spacing of the clay but also enthalpic interaction between the clay surface and the polymer blend. The degree of dispersion of silicate layers in the blend matrix has been characterised by X‐ray diffraction. The improved adhesion between the phases and the fine morphology of the dispersed phase contributes to the improvement in the mechanical and thermal properties of the final polymer blend–organoclay composites over PLA/PBSA blend. On the basis of these results, we propose a general understanding on how the morphology of the blends is related to the final properties.

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Mimicking Lotus Leaf: Development of Micro‐Nanostructured Biomimetic Superhydrophobic Polymeric Surfaces by Ultrafine Powder Coating Technology
Authors: Mozumder Mohammad Sayem , Zhang Hui , Zhu Jesse
Published: May 2011

This study demonstrates the development of polymeric superhydrophobic surfaces by a solvent‐free ultrafine powder coating (UPC) technique for the first time. The developed surfaces exhibit lotus effect with water contact angles (CAs) of over 160° and sliding angle (SA) of less than 5°. It is evident that the higher CA and lower SA of the low‐energy surfaces are attributed to the appropriate surface textures of micro‐ and/or nano‐scales. AFM and SEM images revealed the unique double‐scale hierarchical (micro‐ and nano) structures on the developed superhydrophobic surfaces. As an additional advantage, these superhydrophobic UPC technology eliminates the use of toxic solvents that are responsible for the hazardous emissions of VOCs. Therefore, fabrication of polymeric superhydrophobic surfaces by solvent‐free PC technique has enormous opportunities for a revolutionary expansion in coating industry to save the surfaces from the intervention of moisture.

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Ultra‐wideband monopole antenna with modified triangular patch
Authors: Sadeghzadeh R. A. , Zehforoosh Y. , Mirmotahhary N.
Published: May 2011

This article presents the results of a novel triangular monopole antenna that exhibits multioctave performance.This modification significantly improves the antenna's impedance bandwidth by 158% over an ultra‐wideband frequency. The antenna's simulated return loss and radiation patterns show very good correlation with the fabricated antenna's measured results. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26093
Terahertz wave bandpass filter based on metamaterials
Authors: Jin Ning , Li Jiu‐Sheng
Published: May 2011

We designed and demonstrated experimentally a narrow terahertz wave bandpass filter based on metamaterials. By using terahertz time‐domain spectroscopy system, we examined the transmittance spectra for the proposed terahertz wave filter. The experimental results show that terahertz wave bandpass filter with a narrow transmission bandwidth (1.5%) centered at 2.0 THz, transmittance peak of 0.56419 (i.e., insertion loss of 2.48 dB) and very sharp edges can be achieved. The measurement results closely correspond to the simulated predictions are observed. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26097
A planar triangular monopole antenna with modified ground for UWB application
Authors: Mu Xin , Gong Shu‐Xi , Hong Tao
Published: May 2011

A new design about planar triangular monopole antenna using a modified ground plane for bandwidth enhancement is proposed. By symmetrically etching a pair of modified L‐shaped slots in the ground plane, the impendence bandwidth is increased to 2.5–10.8 GHz under the condition of VSWR<2. Comparing with the original antenna (not slotted), the operating band of the proposed antenna is largely expended, whereas good radiation characteristics hold. The measured and simulated results show that the operating band of the proposed antenna completely covers the frequency range of ultra‐wide band (UWB). © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26100
Dual band frequency selective surface based on circular aperture‐coupled patches
Authors: Zhou Hang , Qu Shao‐Bo , Lin Bao‐Qin , Zhang Jie‐Qiu , Gu Chao , Ma Hua , Xu Zhuo , Bai Peng , Peng Wei‐Dong
Published: May 2011

A dual band frequency selective surface (FSS) based on circular aperture‐coupled patches is presented. The technique is based on using two same structures with different sizes. A special topology is proposed to arrange the two different sizes structures. Each structure is composed of two circular patches and a circular coupling aperture. The dual band FSS has a second‐order band pass responses at each band of operation and owes its advantages to high selectivity and stable performance for both various incident angles and different polarizations. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26102