bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of density of anisotropic microstamped silica thin films on guided bone tissue regeneration—In vitrostudy
Authors: Pelaez‐Vargas Alejandro , Gallego‐Perez Daniel , Carvalho Angela , Fernandes Maria H. , Hansford Derek J. , Monteiro Fernando J.
Published: January 2013

The growing demand for better implant aesthetics has led to increased research on the development of all‐ceramic dental implants. The use of microtextured coatings with enhanced properties has been presented as a viable way to improve tissue integrability of all‐ceramic implants. The aim of this study was to evaluate the effects of different densities of anisotropic microtextured silica thin films, which served as a model coating, on the behavior of human osteoblast‐like cells. The differential responses of human osteoblast‐like cells to anisotropic silica microtextures with varying densities, produced via a combination of sol–gel and soft lithography processing, were evaluated in terms of alignment, elongation (using fluorescence microscopy), overall cellular activity, and the expression/activity levels of alkaline phosphatase (ALP). Statistical analysis was conducted using one‐way ANOVA/Tukey HSDpost hoctest. The thin films were thoroughly characterized via scanning electron microscopy/energy dispersive spectroscopy, Fourier transform infrared, and contact angle measurements. Thin film characterization revealed increased nanoscale roughness and reduced wettability on the micropatterned surfaces. Cell culture experiments indicated that the microtextures induced cell alignment, elongation, and guided colonization on the surface. Cells cultured on denser micropatterns exhibited increased metabolic activity (t= 14–21 days). The early expression/activity levels of ALP released into the medium were found to be significantly higher only on the least dense micropattern. These results suggest the possibility that microstructured silica thin films could be used to guide and enhance peri‐implant cell/tissue responses, potentially improving tissue integration for metallic and all‐ceramic dental implants. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.
Crevice corrosion of biomedical alloys: A novel method of assessing the effects of bone cement and its chemistry
Authors: Bryant Michael , Hu Xinming , Farrar Richard , Brummitt Ken , Freeman Robert , Neville Anne
Published: January 2013

In this study, five commercially available poly(methyl methacrylate) PMMA bone cements were tested to investigate the effects of antibiotics on the severity of crevice corrosion. Bone cements with varying chemistry were also tested. A test method was developed in part reference to ASTM F746‐04. Cylindrical specimens were fitted with a bone cement tapered collar, creating consistent crevice conditions. Crevice corrosion was then studied using potentiodynamic polarization techniques in 0.9% NaCl solution (pH7.4) at 37°C. Surface analyses using a light microscope and scanning electron microscopy were also conducted to investigate the surface morphology after accelerated electrochemical testing. Initial testing of commercially available bone cements indicated that different PMMA bone cements can affect the initiation and propagation mechanism of crevice corrosion. Further studies, utilising electrochemical and mass spectroscopy techniques, have identified that the addition of radiopaque agent and antibiotics affect the initiation mechanisms of 316L stainless steel, whilst significantly increasing the extent of propagation in CoCrMo alloys. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.
Effect of fabrication and processing technology on the biodegradability of magnesium nanocomposites
Authors: Ma Chao , Chen Lianyi , Xu Jiaquan , Fehrenbacher Axel , Li Yan , Pfefferkorn Frank E. , Duffie Neil A. , Zheng Jing , Li Xiaochun
Published: January 2013

Magnesium and its alloys have gained significant attention recently as potential alternatives for biodegradable materials due to their unique biodegradability, biocompatibility, and mechanical properties. However, magnesium alloys tend to have high corrosion rates in biological liquids, thus presenting a potential problem if a magnesium implant/device needs to maintain mechanical integrity for a sufficient period under practical physiological conditions. In this study, hydroxyapatite nanoparticles were used to form magnesium based metal matrix nanocomposites (MMNC) through two processes: friction stir processing (FSP) and a two‐state nanoprocessing (TSnP) combining liquid state ultrasonic processing and solid state FSP. In addition, laser surface melting (LSM) was carried out for further surface treatment. In vitro immersion tests indicated that the corrosion rate of MMNC decreased by 52% compared with pure Mg through FSP. Potentiodynamic polarization tests showed that the corrosion current of MMNC decreased by 71% and 30%, respectively, by TSnP and LSM when compared with pure Mg or untreated counterparts. This study suggests that fabrication of MMNC and further processing through FSP and LSM can robustly enhance the corrosion resistance of magnesium, which will boost its potential for biological applications. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.
Evaluation of the flexural strength of dual‐cure composite resin cements
Authors: Duymus Zeynep Yesil , Yanikoğlu Nuran Dinckal , Alkurt Murat
Published: January 2013

The aim of this study was to evaluate of flexural strength of some adhesive resin cements. Three dual‐cure composite resin cements (Nexus 3; Variolink II, Panavia F) were prepared. The manufacturer's mixing directions for the cements were followed. Adhesive resin cement was mixed, placed in the rectangular portion of the mold. Fifteen specimens were prepared for each cements. The cements were light‐activated with light lamp for 40 s on both and top and bottom surfaces. The each cement specimens were divided into three groups according to time of storage and stored in distilled water for 24 h, 15, and 30 days. Total 45 specimens were stored at 37°C (98.6 0F) in distilled water for 24 h, 15, and 30 days prior to tests. The flexural strength was tested wıth a universal testing machine at a crosshead speed of 0.5 mm/min (0.02 in.) The maximum load was recorded as MPa. The results were analyzed by Analysis of Variance and Duncan test. The Panavia F resin cements content Bisphenol A was showed the highest flexural strength (80.80 MPa) (11.71 ksi) for 24 h. The lowest flexural strength was observed in Nexus 3 (51.00 MPa) (7.39 ksi). It was found significant interaction of material and time (p < 0.05). The types of cement and time of storage was statistically significant on the flexural strengths (p < 0.001). © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.
CT-measured bone attenuation in patients with chronic obstructive pulmonary disease: Relation to clinical features and outcomes
Authors: Romme Elisabeth APM , Murchison John T , Edwards Lisa D , JR van Beek Edwin , Murchison David M , Rutten Erica PA , Smeenk Frank WJM , Williams Michelle C , Wouters Emiel FM , MacNee William ,   on behalf of the Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints (ECLIPSE) study investigators
Published: January 2013

Osteoporosis is highly prevalent in chronic obstructive pulmonary disease (COPD) patients and has been related to several clinical features. However, most studies have been in relatively small COPD cohorts. Therefore, the objectives of this study were to compare bone attenuation measured on low-dose chest computed tomography (CT) between COPD subjects and smoker and nonsmoker controls, and to relate bone attenuation to clinical parameters, inflammatory biomarkers, and outcomes in a large, well-characterized COPD cohort. We studied 1634 COPD subjects, 259 smoker controls, and 186 nonsmoker controls who participated in a large longitudinal study (ECLIPSE). We measured bone attenuation, extent of emphysema, and coronary artery calcification (Agatston score) on baseline CT scans, and clinical parameters, inflammatory biomarkers, and outcomes. Bone attenuation was lower in COPD subjects compared with smoker and nonsmoker controls (164.9 ± 49.5 Hounsfield units [HU] versus 183.8 ± 46.1 HU versus 212.1 ± 54.4 HU, p < 0.001). Bone attenuation was not significantly different between COPD subjects and smoker controls after adjustment for age, sex, and pack-years of smoking. In the COPD subjects, bone attenuation correlated positively with forced expiratory volume in 1 second (FEV1, r = 0.062, p = 0.014), FEV1/forced vital capacity (FVC) ratio (r = 0.102, p < 0.001), body mass index (r = 0.243, p < 0.001), fat-free mass index (FFMI, r = 0.265, p < 0.001), and C-reactive protein (r = 0.104, p < 0.001), and correlated negatively with extent of emphysema (r = −0.090, p < 0.001), Agatston score (r = −0.177, p < 0.001), and interleukin-8 (r = −0.054, p = 0.035). In a multiple regression model, older age, lower FFMI and higher Agatston score were associated with lower bone attenuation. Lower bone attenuation was associated with higher exacerbation (r = −0.057, p = 0.022) and hospitalization (r = −0.078, p = 0.002) rates but was not associated with all-cause mortality. In conclusion, CT-measured bone attenuation was lower in COPD subjects compared with nonsmoker controls but not compared with smoker controls, after adjustment for age, sex, and pack-years of smoking. In the COPD subjects, bone attenuation was associated with age, body composition, and coronary artery calcification but was not associated with all-cause mortality.
Delineating breast cancer cell interactions with engineered bone microenvironments
Authors: Taubenberger Anna V , Quent Verena M , Thibaudeau Laure , Clements Judith A , Hutmacher Dietmar W
Published: January 2013

The mechanisms leading to colonization of metastatic breast cancer cells (BCa) in the skeleton are still not fully understood. Here, we demonstrate that mineralized extracellular matrices secreted by primary human osteoblasts (hOBM) modulate cellular processes associated with BCa colonization of bone. A panel of four BCa cell lines of different bone-metastatic potential (T47D, SUM1315, MDA-MB-231, and the bone-seeking subline MDA-MB-231BO) was cultured on hOBM. After 3 days, the metastatic BCa cells had undergone morphological changes on hOBM and were aligned along the hOBM's collagen type I fibrils that were decorated with bone-specific proteins. In contrast, nonmetastatic BCa cells showed a random orientation on hOBM. Atomic force microscopy-based single-cell force spectroscopy revealed that the metastatic cell lines adhered more strongly to hOBM compared with nonmetastatic cells. Function-blocking experiments indicated that β1-integrins mediated cell adhesion to hOBM. In addition, metastatic BCa cells migrated directionally and invaded hOBM, which was accompanied by enhanced MMP-2 and -9 secretion. Furthermore, we observed gene expression changes associated with osteomimickry in BCa cultured on hOBM. As such, osteopontin mRNA levels were significantly increased in SUM1315 and MDA-MB-231BO cells in a β1-integrin–dependent manner after growing for 3 days on hOBM compared with tissue culture plastic. In conclusion, our results show that extracellular matrices derived from human osteoblasts represent a powerful experimental platform to dissect mechanisms underlying critical steps in the development of bone metastases.
A Simple HPV 18 Detection Method Based on Ultra Specific Primer Immobilized on Glass Slides
Authors: Fidelis Amanda C. , Dutra Rosa F. , Souza Paulo Roberto E. , de Melo Celso Pinto , Maia Maria M. D.
Published: January 2013

This study was carried out to develop a simple and inexpensive method for detection of Human papillomavirus (HPV 18) based on irreversible immobilization of ultra specific primer on silanized glass slides. This method is revealed by Blue Green Loading Dye I (LGC) and compared with conventional polymerase chain reaction (PCR) for endocervical samples. The new method was tested in 40 DNA samples with precancer uterine lesions of women treated in Hospital of Recife PE, Brazil. DNA samples were extracted using Wizard Genomic DNA Purification Kit according to manufacturer's instructions. The samples were tested for HPV 18 by conventional PCR (PCRc) and the products visualized on 1.2% agarose gel, with LGC under UV 260 nm. After that the positive and negative samples to HPV 18 were tested by immobilization method and the results visualized with LGC under UV 260 nm. Both PCRc and immobilization method showed high degree of correlation (95%), whereas comparison between PCRc and immobilization method showed good correlation (100%). PCRc is widely known for detection of HPV because of its high sensitivity and efficiency, but due to high cost it is not yet standardized for use in public health laboratories. In our study, the single‐stranded DNA immobilized method on a glass slide was effective in screening for HPVrevealed by Blue Green and may be an alternative method for diagnosis of HPVonce it offers a fast, and easy handling. J. Clin. Lab. Anal. 27:143–147, 2013. © 2013 Wiley Periodicals, Inc.
Increase of extracellular glutamate concentration increases its oxidation and diminishes glucose oxidation in isolated mouse hippocampus: Reversible by TFB‐TBOA
Authors: Torres Felipe Vasconcelos , Hansen Fernanda , Locks‐Coelho Lucas Doridio
Published: January 2013

Glutamate concentration at the synaptic level must be kept low in order to prevent excitotoxicity. Astrocytes play a key role in brain energetics, and also astrocytic glutamate transporters are responsible for the vast majority of glutamate uptake in CNS. Experiments with primary astrocytic cultures suggest that increased influx of glutamate cotransported with sodium at astrocytes favors its flux to the tricarboxylic acid cycle instead of the glutamate–glutamine cycle. Although metabolic coupling can be considered an emergent field of research with important recent discoveries, some basic aspects of glutamate metabolism still have not been characterized in brain tissue. Therefore, the aim of this study was to investigate whether the presence of extracellular glutamate is able to modulate the use of glutamate and glucose as energetic substrates. For this purpose, isolated hippocampi of mice were incubated with radiolabeled substrates, and CO2 radioactivity and extracellular lactate were measured. Our results point to a diminished oxidation of glucose with increasing extracellular glutamate concentration, glutamate presumably being the fuel, and might suggest that oxidation of glutamate could buffer excitotoxic conditions by high glutamate concentrations. In addition, these findings were reversed when glutamate uptake by astrocytes was impaired by the presence of (3S)‐3‐[[3‐[[4‐(trifluoromethyl)benzoyl]amino]phenyl]methoxy]‐L‐aspartic acid (TFB‐TBOA). Taken together, our findings argue against the lactate shuttle theory, because glutamate did not cause any detectable increase in extracellular lactate content (or, presumably, in glycolysis), because the glutamate is being used as fuel instead of going to glutamine and back to neurons. © 2013 Wiley Periodicals, Inc.
Real‐time Raman spectroscopy measurements to study the uniaxial tension of isotactic polypropylene: a global overview of microstructural deformation mechanisms
Authors: Martin J. , Ponçot M. , Hiver J.M. , Bourson P. , Dahoun A.
Published: January 2013

Micro‐Raman spectroscopy was used to investigate the main deformation micromechanisms of isotactic polypropylene uniaxially stretched at constant temperature (T = 30 °C) under a constant true strain rate ( = 5.10−3 s−1). To accurate measurements namely to be free of the recovering phenomenon which causes in most of the cases interference during post‐mortem analysis, we introduced a new experimental setup combining a Raman spectrometer with a tensile machine piloted by the VidéoTraction™ system. Microstructure is described by essential parameters such as the crystallinity index, the macromolecular orientation both in the crystalline and the amorphous phase, and distribution of the internal stress at the chemical bonds scale. For each, a well‐tried Raman spectral criterion was used. Cross‐checking of these results, obtained with a minimum of tensile tests, allows a more complete understanding of the deformation micromechanisms of semi‐crystalline polymer. Copyright © 2013 John Wiley & Sons, Ltd.
Amphiphilic Unimolecular Nanoparticles Based on a Hyperbranched Polyacrylate Core and a PNIPAm Shell: Synthesis via ATRP and Properties
Authors: Cai Yong , Liu Yu‐Yang
Published: January 2013

A novel amphiphilic unimolecular nanoparticle, multi‐HPBPEA‐g‐PNIPAm, for encapsulation and release of hydrophobic guest molecules, is developed. The polymer shows core–shell architecture and is synthesized from inimer 2‐((2‐bromopropionyl)oxy)ethyl acrylate (BPEA) by atom transfer radical polymerization (ATRP) in three steps. The hydrophobic core (multi‐HPBPEA) is composed of hyperbranched poly(2‐((2‐bromopropionyl)oxy)ethyl acrylate) (HPBPEA), which is synthesized by self‐condensing vinyl polymerization (SCVP) of BPEA. Multi‐HPBPEA‐g‐PNIPAm is obtained by multi‐HPBPEA core initiating ATRP of N‐isopropylacrylamide (NIPAm). The encapsulation behavior of the core of multi‐HPBPEA‐g‐PNIPAm in an aqueous solution is investigated by fluorescent spectra. It is found that multi‐HPBPEA‐g‐PNIPAm can efficiently encapsulate and release a hydrophobic drug like nifedipine.

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Spreading and Dewetting of Single Bottle‐Brush Macromolecules on Nanofacetted SrTiO3 Substrate as Induced by Different Vapours
Authors: Gallyamov Marat O. , Tartsch Bernd , Börner Hans G. , Matyjaszewski Krzysztof , Khokhlov Alexei R. , Möller Martin
Published: January 2013

Responsive bottle‐brush macromolecules undergo vapour‐induced spreading and dewetting cycles on facetted SrTiO3 surfaces with a saw‐toothed topography. The macromolecular transformations are followed by environmental scanning force microscopy in real time. A set of the wafers with different groove periods are tested as the substrates for the transforming macromolecules. In order to estimate the orienting influence of the anisotropic patterned substrate, an asymmetry factor is measured for the dewetting macromolecules at different groove periods. The most evident template influence of the substrate occurs when the period is in range of 20–40 nm. This range is commensurable with the typical lateral dimension of the adsorbed bottle‐brush macromolecules with a dense flat corona of extended side chains.

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Tripod omnidirectional low profile antenna: A vertically polarized antenna with 90% bandwidth
Authors: Zürcher J.‐F.
Published: January 2013

A new vertically polarized omnidirectional antenna, inspired by an old design, has been studied, optimized, realized, and measured. With a radiation pattern similar to the classical monopole on a ground plane, the proposed antenna concept provides a much larger bandwidth and a very low profile. This antenna has numerous potential applications for mobile communications, UWB, and others. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:516–521, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27340
Broadband phase shifters using complementary frequency‐dependent Δphase of low‐/high‐pass filters
Authors: Chung Younkyu , Deckman Blythe C. , DeLisio Michael P.
Published: January 2013

This letter presents a simple and compact design approach for broadband analog phase shifters and its demonstration. An octave bandwidth can be obtained by alternately cascading low‐pass filters (LPF) and high‐pass filters (HPF) that importantly provide complementary phase‐changing characteristics over “frequencies.” Achievable phase change per segment can be multiplied by cascading multiple segments that operate as independent phase shifters, thereby reaching 360 degrees of phase shift. We demonstrate one‐ and two‐segment phase shifters consisting of cascaded LPF‐HPF‐LPF structures, of which capacitors in each filter are implemented by varactors, over a frequency range from 0.7 GHz to 1.4 GHz. Measurements show 65.8 degree average phase shifts from the single‐segment and 128 degree from the double‐segment, which is about twice as much as the single‐segment shifter's. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:664–666, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27345
UWB printed plaque monopole antennas for tri‐band rejection
Authors: Mandal Tapan , Das Santanu
Published: January 2013

In this article, a printed plaque monopole antenna fed by a microstrip line for ultrawideband (UWB) width with triple notch band has been presented.The antenna is then modified to possess band rejection at the wireless local area network (5.1–5.8 GHz) by an inverted U‐shape slot or Π‐shape slot, or Λ–shape slot within the radiating patch. In addition, two half wavelength slots (U‐slot) are cut in the radiating patch to generate the first and third notch band in 3.25–3.75 GHz for WiMAX and 7.25–7.75 GHz for down link of X‐band satellite communication system. Surface current distributions and transmission line model are used to analyze the effect of these slots. The proposed antennas are simulated and fabricated. Radiation pattern shows good omnidirectional radiation patterns in the H‐plane and monopole like patterns in the E‐plane. The proposed antenna gain varies from 1.63 to 5.05 dB over the whole UWB region excluding at notch band. The design antenna has a compact size of 30 × 30 mm2. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:674–680, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27359
Dispersion characteristics of 1D PBG structures composed of subwavelength dipole elements
Authors: Khodami Maryam , Shaker Jafar , Yagoub Mustapha C. E.
Published: January 2013

In this article, an innovative approach for characterization of one dimensional photonic band gap (PBG) structures comprised of subwavelength dipole elements is presented.Through an efficient S‐ to T‐parameters conversion technique, polarization sensitivity of the subwavelength cell element was exploited to propose a novel combination of elements which allows achieving PBGs with simultaneous frequency and polarization selectivity. The proposed approach demonstrated that dispersion characteristics of each orthogonal polarization can be independently adjusted with dipole elements parallel to that same polarization. The structure has potential application in orthomode transducer and generally whenever the polarization of the incoming signal is to be used as a means of separating it from another signal in the same frequency band that is of orthogonal polarization. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:611–615, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27378
Small Wi‐Fi chip antenna using a backside ground capacitance
Authors: Oh Saewon , Kim Hyeongdong
Published: January 2013

In this article, a new small chip antenna for Wi‐Fi applications in mobile handsets is proposed. To achieve miniaturization, the proposed antenna is designed to have a backside ground. The proposed antenna has an S‐shaped structure, which is designed on liquid crystal polymer with εr = 3.5. The size of the proposed antenna is 6.0 × 3.0 × 1.2 mm3. The measured impedance bandwidth under a voltage standing wave ratio of 2 is 300 MHz (fractional bandwidth: 12.2%, 2.3–2.6 GHz), and the peak gain is 1.42 dBi. The proposed antenna is designed using a commercial software tool, CST Microwave Studio, and the fabricated antenna is measured using a network analyzer and an anechoic chamber. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:580–582, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27379
Far‐IR multiband dual‐polarization perfect absorber for wide incident angles
Authors: Yeo Woon‐Gi , Nahar Niru K. , Sertel Kubilay
Published: January 2013

We present a frequency selective surface (FSS) based, electrically thin perfect absorber with multiband and/or broadband performance in the Far‐IR band. We start by introducing small metallic loadings to the well‐known crossed‐dipole FSS structure. We demonstrate that these parasitic inclusions allow for much improved design flexibility for wide‐angle perfect absorbers using SiC and Silicon substrates. The numerical simulation results of proposed absorbers show that the design achieves dual‐band performance for wide incident angles in both transverse and transverse magnetic polarizations, with near perfect absorption characteristics. Furthermore, simple compositions of scaled versions of the proposed FSS elements are shown to achieve multiband and broadband characteristics. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:632–636, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27387
A dual‐band WLAN/UWB printed wide slot antenna for mimo/diversity applications
Authors: Mohammad Sajad , nezhad ali , Hassani Hamid Reza , Foudazi Ali
Published: January 2013

In this article, a dual‐band WLAN/ultrawideband (UWB) printed wide slot microstrip‐fed antenna is presented for multi‐input multi‐output (MIMO)/diversity applications.The proposed antenna consists of a U‐shaped patch, a T‐shaped monopole path, and a pentagonal wide slot in the ground plane. The antenna is designed to cover both the WLAN (2.4–2.485 GHz) and UWB (3.1–10.6 GHz) ranges, with value of S11 below −10 dB. The antenna is constructed on a FR4 substrate with overall dimensions of 28 × 28 × 1 mm3. It is shown that the proposed dual‐band antenna is suitable for diversity polarization applications. The simulation results show that the different configurations of the antenna in the MIMO/diversity have good S‐parameters over the operating frequency bands. The simulation and measured results of the proposed dual‐band antenna as well as that of the MIMO/diversity antenna configuration agree well. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:461–465, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27391
Design, measurement, and characterization of dual‐band left‐handed metamaterials with combined elements
Authors: Min‐Hua Li , He‐Lin Yang , Hai Lin , Bo‐Xun Xiao
Published: January 2013

We report on a new kind of planar left‐handed metamaterial with both simulations and experiments in this article. Dual electric and magnetic resonance frequency bands are experimentally realized by introducing two different metallic elements in one unit cell, which offers a convenient approach in building dual‐band or multiband negative‐index metamaterials. The effective electromagnetic parameters obtained from the measured S‐parameters indicate that negative refractive indexes are verified near 8.5 and 12 GHz with both negative permittivity and negative permeability. Field and current distribution at the dual resonances are also examined. At last, we calculated the radiated power of the magnetic dipole moments along y‐axis. The idea can help us to fabricate dual‐band or multiband metamaterial absorbers, filters, and antennas. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:493–497, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27399
Diffusion‐weighted 3D multislab echo planar imaging for high signal‐to‐noise ratio efficiency and isotropic image resolution
Authors: Engström Mathias , Skare Stefan
Published: January 2013

Purpose

To acquire isotropic high‐resolution, signal‐to‐noise ratio (SNR) efficient, 3D encoded diffusion‐weighted MRI data.

Methods

Multiple Fourier encoded slabs were combined into one full volume, using a generalized autocalibrating partially parallel acquisitions (GRAPPA) accelerated diffusion‐weighted 3D multislab echo planar imaging (EPI) sequence with 2D phase navigation and in‐plane motion correction.

Results

Reconstructed data with 1.5‐mm3 nominal resolution is presented and shown under the influence of motion and with variable slab thicknesses. The SNR efficiency between diffusion‐weighted 3D multislab EPI and DW 2D ss‐EPI is compared. Finally, a 1.3‐mm3 full brain scan with 45 diffusion directions is presented.

Conclusions

Diffusion‐weighted 3D multislab EPI has been presented as an alternative sequence for high‐resolution and high‐SNR full brain coverage diffusion studies. Compared with the gold standard 2D diffusion‐weighted single‐shot Echo Planar Imaging, the SNR efficiency is significantly higher. Magn Reson Med 70:1507–1514, 2013. © 2013 Wiley Periodicals, Inc.
Reliability of two clinically relevant fiber pathways reconstructed with constrained spherical deconvolution
Authors: Kristo Gert , Leemans Alexander , Raemaekers Mathijs , Rutten Geert‐Jan , de Gelder Beatrice , Ramsey Nick F.
Published: January 2013

The single diffusion tensor model is inadequate for the reconstruction of fiber pathways in brain regions with multiple fiber orientations. To overcome this limitation, constrained spherical deconvolution has been proposed. A high reliability of constrained spherical deconvolution is, however, a pre‐requisite for its use in clinical applications. Reliability of reconstructed fiber pathways can be assessed in terms of architectural (addressing their spatial configuration) and microstructural (addressing diffusion‐derived measures along the fibers) reproducibility. We assess the reliability for two clinically relevant fiber pathways: the corticospinal tract and arcuate fasciculus. The fiber pathways were reconstructed using constrained spherical deconvolution in 11 healthy subjects who were scanned on three occasions. Coefficients of variations of diffusion‐derived measures were used to assess the microstructural reproducibility. Image correlation and fiber overlap were used to assess the architectural reproducibility. The mean correlation between sessions was 72% for both the corticospinal tract and arcuate fasciculus. The mean overlap between sessions was 63% for the corticospinal tract and 58% for the arcuate fasciculus. Coefficients of variations of diffusion‐derived measures showed very low variation (all measures <3.1%). These results are comparable with reliability results based on the diffusion tensor model, which is commonly used in clinical settings. The reliability results found here are, therefore, promising to further investigate the use of constrained spherical deconvolution in clinical practice. Magn Reson Med 70:1544–1556, 2013. © 2013 Wiley Periodicals, Inc.
Improved MRIR2* relaxometry of iron‐loaded liver with noise correction
Authors: Feng Yanqiu , He Taigang , Gatehouse Peter D. , Li Xinzhong , Harith Alam Mohammed , Pennell Dudley J. , Chen Wufan , Firmin David N.
Published: January 2013

Accurate and reproducible MRI R2* relaxometry for tissue iron quantification is important in managing transfusion‐dependent patients. MRI data are often acquired using array coils and reconstructed by the root‐sum‐square algorithm, and as such, measured signals follow the noncentral chi distribution. In this study, two noise‐corrected models were proposed for the liver R2* quantification: fitting the signal to the first moment and fitting the squared signal to the second moment in the presence of the noncentral chi noise. These two models were compared with the widely implemented offset and truncation models on both simulation and in vivo data. The results demonstrated that the “slow decay component” of the liver R2* was mainly caused by the noise. The offset model considerably overestimated R2* values by incorrectly adding a constant to account for the slow decay component. The truncation model generally produced accurate R2* measurements by only fitting the initial data well above the noise level to remove the major source of errors, but underestimated very high R2* values due to the sequence limit of obtaining very short echo time images. Both the first and second‐moment noise‐corrected models constantly produced accurate and precise R2* measurements by correctly addressing the noise problem. Magn Reson Med 70:1765–1774, 2013. © 2013 Wiley Periodicals, Inc.
Uric acid best predicts metabolically unhealthy obesity with increased cardiovascular risk in youth and adults
Authors: Mangge Harald , Zelzer Sieglinde , Puerstner Peter , Schnedl Wolfgang J. , Reeves Gloria , Postolache Teodor T. , Weghuber Daniel
Published: January 2013

Objective:

The obesity prevalence is growing worldwide and largely responsible for cardiovascular disease, the most common cause of death in the western world. The rationale of this study was to distinguish metabolically healthy from unhealthy overweight/obese young and adult patients as compared to healthy normal weight age matched controls by an extensive anthropometric, laboratory, and sonographic vascular assessment.

Design and Methods:

Three hundred fifty five young [8 to < 18 years, 299 overweight/obese(ow/ob), 56 normal weight (nw)] and 354 adult [>18‐60 years, 175 (ow/ob), 179 nw)] participants of the STYJOBS/EDECTA (STYrian Juvenile Obesity Study/Early DEteCTion of Atherosclerosis) cohort were analyzed. STYJOBS/EDECTA (NCT00482924) is a crossectional study to investigate metabolic/cardiovascular risk profiles in normal and ow/ob people free of disease except metabolic syndrome (MetS).

Results:

From 299 young ow/ob subjects (8‐< 18 years), 108 (36%), and from 175 adult ow/ob subjects (>18‐60 years), 79 (45%) had positive criteria for MetS. In both age groups, prevalence of MetS was greater among males. Overweight/obese subjects were divided into “healthy” (no MetS criterion except anthropometry fulfilled) and “unhealthy” (MetS positive). Although percentage body fat did not differ between “healthy” and “unhealthy” ow/ob, nuchal and visceral fat were significantly greater in the “unhealthy” group which had also significantly higher values of carotid intima media thickness (IMT). With MetS as the dependent variable, two logistic regressions including juveniles <18 years or adults >18 years were performed. The potential predictor variables selected with the exception of age and gender by t test comparisons included IMT, ultrasensitive c‐reactive protein (US‐CRP), IL‐6, malondialdehyde (MDA), oxidized LDL, leptin, adiponectin, uric acid (UA), aldosterone, cortisol, transaminases, fibrinogen. In both groups, uric acid and in adults only, leptin and adiponectin, turned out as the best predictor.

Conclusion:

Serum levels of UA are a significant predictor of unhealthy obesity in juveniles and adults.
Comparative Lung Function Performance of Stroke Survivors and Age‐matched and Sex‐matched Controls
Authors: Ezeugwu Victor Emeka , Olaogun Matthew , Mbada Chidozie Emmanuel , Adedoyin Rufus
Published: January 2013

Background and Purpose

Reduced endurance and excessive fatigue in stroke survivors (SS) during exercise may be linked to impairment of lung function and breathing mechanics, but little is known about lung function of SS. The purpose of this study is to determine lung function (forced expiratory volume in 1 second [FEV1], forced vital capacity [FVC], FEV1/FVC ratio and peak expiratory flow [PEF]) and influence of anthropometrics on lung function in SS compared with healthy controls (CG).

Methods

In this case–control, cross‐sectional study, we recruited 70 participants (42 males, 28 females), comprising 35 SS and 35 CG (range 34–73 years). Anthropometrics were measured using standard instruments and procedure. Chest excursion was measured at the axilla, xiphoid and lower costal levels. Lung function indices were measured using a micro‐computerized spirometer. Ethical approval was obtained from the Ethics and Research Committee of Obafemi Awolowo University Teaching Hospital, Ile‐Ife, Nigeria.

Results/Findings

Compared with the CG, the SS had significantly lower values for FEV1 (1.99 ± 0.66 vs. 2.36 ± 0.45 L, p = 0.004), FVC (2.55 ± 0.70 vs. 2.90 ± 0.54 L, p = 0.014), PEF (3.88 ± 1.38 vs. 5.24 ± 1.30 L second−1, p = 0.001) and chest excursion (3.0 ± 0.71 vs. 3.5 ± 0.91 cm, p = 0.018). Correlations between chest excursion, FEV1, FVC and PEF were not significant (p > 0.05).

Discussion

The weakness of respiratory muscles associated with stroke may have contributed to decreases in lung function observed. There was a significant reduction in chest excursion of SS compared with CG. Chest excursion has been used as an indicator of respiratory muscle function because the range of motion of the thorax serves the respiration. Movements of the thorax influence the content of the thorax cavity, leading to alterations in lung volumes.

Implications for Physiotherapy Practice

Stroke survivors have lower lung function when compared with CG; this has implications for clinicians in stroke rehabilitation, underscoring the importance for inclusion of interventions to improve lung function. Copyright © 2013 John Wiley & Sons, Ltd.
Physicochemical changes in phosphorylase kinase induced by its cationic activator Mg2+
Authors: Liu Weiya , Nadeau Owen W. , Sage Jessica , Carlson Gerald M.
Published: January 2013

For over four decades free Mg2+ ions, that is, those in excess of MgATP, have been reported to affect a wide variety of properties of phosphorylase kinase (PhK), including its affinity for other molecules, proteolysis, chemical crosslinking, phosphorylation, binding to certain monoclonal antibodies, and activity, which is stimulated. Additionally, for over three decades Mg2+ has been known to act synergistically with Ca2+, another divalent activator of PhK, to affect even more properties of the enzyme. During all of this time, however, no study has been performed to determine the overall effects of free Mg2+ ions on the physical properties of PhK, even though the effects of Ca2+ ions on PhK's properties are well documented. In this study, changes in the physicochemical properties of PhK induced by Mg2+ under nonactivating (pH 6.8) and activating (pH 8.2) conditions were investigated by circular dichroism spectroscopy, zeta potential analyses, dynamic light scattering, second derivative UV absorption, negative stain electron microscopy, and differential chemical crosslinking. The effects of the activator Mg2+ on some of the properties of PhK measured by these techniques were found to be quite different at the two pH values, and displayed both differences and similarities with the effects previously reported to be induced by the activator Ca2+ (Liu et al., Protein Sci 2008;17:2111–2119). The similarities may reflect the fact that both cations are activators, and foremost among their similarities is the dramatically less negative zeta potential induced by their binding to PhK.
317 GHz InAlGaN/GaN HEMTs with extremely low on‐resistance
Authors: Lee Dong Seup , Laboutin Oleg , Cao Yu , Johnson Wayne , Beam Edward , Ketterson Andrew , Schuette Michael , Saunier Paul , Kopp David , Fay Patrick , Palacios Tomás
Published: January 2013

This paper reports depletion‐mode In0.13Al0.83Ga0.04N/GaN high electron mobility transistors (HEMTs) on a SiC substrate with a record current gain cutoff frequency (fT) of 317 GHz. Thanks to the combination of high electron mobility, regrown n+ InGaN/GaN ohmic contacts and scaled source‐to‐drain distance, the devices have an very low on‐resistance of 0.4 Ω·mm. This very low resistance enables a significant reduction of the transistor parasitic delay and devices with a peak fT of 317 GHz have been demonstrated for a 26 nm gate length. The device performance is limited by a relatively thick top barrier which causes serious short‐channel effects (SCEs) in the devices with gate length below 50 nm. It is expected that a suppression of the SCEs will render further improvements in frequency performance in future devices. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Systematic theoretical investigations for the polytypism in SiC
Authors: Ito Tomonori , Akiyama Toru , Nakamura Kohji
Published: January 2013

SiC polytypes in bulk form is systematically investigated using ab initio pseudopotential approach for the total energy calculations in four structures such as 3C (zinc blende), 6H, 4H, and 2H (wurtzite) structures with vacancy and nitrogen doping. Our calculated energy differences ΔE among four structures reveal that 3C and 4H are favorable for prefect SiC. The ΔE for SiC with vacancy suggests the most stable structures such as 6H with Si‐vacancy and 4H with C‐vacancy. The calculated vacancy formation energies suggest that C‐rich condition prefers 6H whereas 4H is favored under Si‐rich condition. Furthermore, nitrogen substituting for carbon and silicon respectively stabilizes 3C and 4H. These calculated results are consistent with experimental findings. The destabilization due to the vacancy formation and stabilization due to nitrogen of 3C‐SiC are discussed by bond charge calculations and our simple formula of ΔE. It is found that vacancy formation inducing large deficit of bond charges favors 6H‐ and 4H‐SiC and nitrogen‐doping increasing bond charges stabilizes 3C‐SiC. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
(111) InAs/GaSb type‐II strained layer superlattice material for high operating temperature detection
Authors: Plis Elena , Klein Brianna , Myers Stephen , Gautam Nutan , Krishna Sanjay
Published: January 2013

We report on the detailed radiometric characterization of the mid‐wave infrared InAs/GaSb type‐II strained layer superlattice detectors grown on GaSb (111) substrate. A red shift of 1.7 μm (at 295 K) was observed with respect to a similar detector grown on GaSb (100) substrate. We have measured, at 295 K and λ100% cut‐off = 5.6 μm, a dark current density of 0.53 A/cm2 (at ‐50 mV) and a Johnson noise limited D* of 8.5 x 109Jones, which are superior values to state‐of‐the‐art T2SL detectors with the same (pin) design grown on conventional GaSb (100) substrates and operating in a similar wavelength range. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ultrafast transverse thermoelectric response in c‐axis inclined epitaxial La0.5Sr0.5CoO3 thin films
Authors: Yu Lan , Wang Yong , Zhang Pengxiang , Habermeier Hanns‐Ulrich
Published: January 2013

Ultrafast transverse thermoelectric voltage response has been observed in c‐axis inclined epitaxial La0.5Sr0.5CoO3thin films. Voltage signals with the rise time of 7 ns have been detected under the irradiation of pulse laser with duration of 28 ns. A concept, named response rate ratio, has been proposed to evaluate the intrinsic response rate, and this ratio in La0.5Sr0.5CoO3is smaller than that in other reported materials. The low resistivity is thought to be responsible for the ultrafast response, as low resistivity induces small optical penetration depth, and response time has a monotonous increasing relationship with this depth.

magnified image

Transverse thermoelectric voltage with the rise time of 7 ns in La0.5Sr0.5CoO3thin film.

(© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Executive preferences for governance modes and exchange partners: An information economics perspective
Authors: Reuer Jeffrey J. , Tong Tony W. , Tyler Beverly B. , Ariño Africa
Published: January 2013

This study investigates how executives address information asymmetry and adverse selection surrounding international joint ventures (IJVs) and acquisitions. We argue that executives can address such exchange hazards not only through their governance decisions, as prior research indicates, but also through their selection of exchange partners. Our experimental design complements prior research on firms' governance choices in three ways: (1) by incorporating multiple potential exchange partners rather than taking a single partner as given for a realized transaction; (2) by accommodating multiple potential entry modes to address interdependencies across governance structures; and (3) by providing direct evidence on executives' assessments ofIJVsand acquisitions. We join together organizational governance research and decision‐making research onIJVpartner selection, two literatures that have largely developed separately. Copyright © 2013 John Wiley & Sons, Ltd.
Platform competition: Strategic trade‐offs in platform markets
Authors: Cennamo Carmelo , Santalo Juan
Published: January 2013

Because the literature on platform competition emphasizes the role of network effects, it prescribes rapidly expanding a network of platform users and complementary applications to capture entire markets. We challenge the unconditional logic of a winner‐take‐all (WTA) approach by empirically analyzing the dominant strategies used to build and position platform systems in the U.S. video game industry. We show that when platform firms pursue two popular WTA strategies concurrently and with equal intensity (growing the number and variety of applications while also securing a larger fraction of those applications with exclusivity agreements), it diminishes the benefits of each strategy to the point that it lowers platform performance. We also show that a differentiation strategy based on distinctive positioning improves a platform's performance only when a platform system is highly distinctive relative to its rivals. Our results suggest that platform competition is shaped by important strategic trade‐offs and that the WTA approach will not be universally successful. Copyright © 2013 John Wiley & Sons, Ltd.
Implications of internal organization structure for firm boundaries
Authors: Weigelt Carmen , Miller Douglas J.
Published: January 2013

Knowledge issues are central to governance choice. Organization structure influences knowledge flows and costs of knowledge creation and exchange inside the firm. Yet the question of how a firm's internal structure affects its governance choice for new activities has received scant empirical attention. We examine the role of internal structure, specifically unit autonomy and lateral coordination, in a firm's governance decision for new, knowledge‐intensive activities. The findings show that internal structure is a ‘shift parameter’ that affects governance choice by moderating the relationship between task complexity and degree of integration. The empirical setting is the U.S. banking industry and its adoption of Internet banking. Copyright © 2013 John Wiley & Sons, Ltd.
A Confluence of Third‐Phase Science and Dialogic Design Science
Authors: Bausch Kenneth C. , Flanagan Thomas R.
Published: January 2013

Gerard de Zeeuw introduced the term ‘Third Phase Science’ in 1997. A deliberative method that is called dialogic design science (see http://dialogicdesignscience.wikispaces.com) illustrates an effective way of implementing third‐phase science as a means of understanding and adapting complex social situations. This paper explains De Zeeuw's concept in non‐specialist language and expands on the historical context of third‐phase science as a means of addressing contemporary needs. It shows how dialogic design science completes third‐phase science as an axiomatic science and makes third‐phase science into a valuable design methodology. Copyright © 2013 John Wiley & Sons, Ltd.