bluuebunny/crossref_metadata_2025 huggingface dataset:
Robust method for 3D arterial spin labeling in mice
Authors: Chugh Brige Paul , Bishop Jonathan , Zhou Yu‐Qing , Wu Jian , Henkelman R. Mark , Sled John G.
Published: November 2011

Arterial spin labeling is a versatile perfusion quantification methodology, which has the potential to provide accurate characterization of cerebral blood flow (CBF) in mouse models. However, a paucity of physiological data needed for accurate modeling, more stringent requirements for gradient performance, and strong artifacts introduced by magnetization transfer present special challenges for accurate CBF mapping in the mouse. This article describes robust mapping of CBF over three‐dimensional brain regions using amplitude‐modulated continuous arterial spin labeling. To provide physiological data for CBF modeling, the carotid artery blood velocity distribution was characterized using pulsed‐wave Doppler ultrasound. These blood velocity measurements were used in simulations that optimize inversion efficiency for parameters meeting MRI gradient duty cycle constraints. A rapid slice positioning algorithm was developed and evaluated to provide accurate positioning of the labeling plane. To account for enhancement of T1 due to magnetization transfer, a binary spin bath model of magnetization transfer was used to provide a more accurate estimate of CBF. Finally, a study of CBF was conducted on 10 mice with findings of highly reproducible inversion efficiency (mean ± standard‐error‐of‐the‐mean, 0.67 ± 0.03), statistically significant variation in CBF over 12 brain regions (P < 0.0001) and a mean ± standard‐error‐of‐the‐mean whole brain CBF of 219 ± 6 mL/100 g/min. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
Ultrasound evaluation of peripheral neuropathy in POEMS syndrome
Authors: Lucchetta Marta , Pazzaglia Costanza , Granata Giuseppe , Briani Chiara , Padua Luca
Published: November 2011

Introduction:

Polyneuropathy, organomegaly, endocrinopathy, M protein, skin changes (POEMS) syndrome is a rare multisystem disorder associated with plasma cell dyscrasia whose main neurological feature is a demyelinating polyneuropathy. The aim of our study was to assess the pattern of ultrasound (US) nerve abnormalities in POEMS syndrome patients.

Methods:

Eight POEMS syndrome patients underwent neurological examination and US evaluation of the median, ulnar, fibular, tibial, and sural nerves. Nerve cross‐sectional area and echogenicity abnormalities were analyzed.

Results:

US abnormalities were mostly localized at entrapment sites. Enlargements outside the entrapment sites were uncommon. No correlation was found between muscle weakness and focal US findings.

Conclusions:

No specific pattern of US abnormalities was identified in this cohort of patients with POEMS syndrome. The lack of correlation between US and clinical findings may be secondary to the chronic nerve damage that is common in POEMS syndrome, where the diagnosis is often delayed. Muscle Nerve 2011
Substance abuse increases the risk of neuropathy in an HIV‐infected cohort
Authors: Robinson‐Papp Jessica , Gelman Benjamin B. , Grant Igor , Singer Elyse , Gensler Gary , Morgello Susan ,   for the National NeuroAIDS Tissue Consortium
Published: November 2011

Introduction: Human immunodeficiency virus (HIV)‐infected patients commonly develop distal symmetric polyneuropathy (DSP). Age, ethnicity, and toxic exposures may influence the risk. In this study we examined the association between substance use, antiretrovirals, ethnicity, and incident neuropathy in an HIV‐infected cohort. Methods: Data were obtained from the National NeuroAIDS Tissue Consortium (NNTC), an ongoing, prospective cohort started in 1998. Cox proportional hazards models were used to examine the association of substance use, demographics, neurotoxic antiretrovirals, and laboratory parameters with incident neuropathy in 636 participants who were neuropathy‐free at baseline. Results: The cumulative incidence of DSP was 41%. Substance use (P = 0.04), number of substances used (P = 0.04), and longer duration of HIV infection (P = 0.05) were associated with incident DSP, but demographic factors, use of neurotoxic antiretrovirals, and laboratory parameters were not. Conclusions: Substance use and longer duration of HIV infection are risk factors for DSP in HIV‐infected patients. Use of multiple substances may be particularly risky. Muscle Nerve, 2012
Electrical impedance myography in spinal muscular atrophy: A longitudinal study
Authors: Rutkove Seward B. , Gregas Matt C. , Darras Basil T.
Published: November 2011

Introduction: New approaches for assessing disease progression in spinal muscular atrophy (SMA) are needed. In this study, we evaluate whether electrical impedance myography (EIM) can detect disease progression in SMA compared with a group of healthy children of similar age. Methods: Twenty‐eight children with SMA and 20 normal children underwent repeated EIM testing in four muscles at regular intervals for up to 3 years. An average rate of change of EIM was calculated for each subject and normalized to subcutaneous fat thickness and muscle girth. Results: Multiple EIM parameters showed a change in normal subjects over a mean of 16.7 months; however, no change was found in SMA patients over this period. Conclusions: EIM could detect non–mass‐dependent muscle maturation in healthy children. In contrast, the muscle in children with SMA, as measured by EIM, was virtually static, showing no evidence of growth or active deterioration. Muscle Nerve, 2012
The thoracic outlet syndromes
Authors: Ferrante Mark A.
Published: November 2011

The term thoracic outlet syndrome (TOS) refers to a heterogeneous group of disorders, all of which have in common compression of one or more neurovascular elements at some point within the thoracic outlet. Of the five disorders comprising this group, four have all of the features expected of a syndrome—a recognized constellation of clinical features; an anatomic derangement accounting for these features; and a method of testing that identifies the anatomic derangement. Consequently, their recognition and management are relatively straightforward. Conversely, one of these five disorders (nonspecific TOS) lacks these correlations, which has generated considerable debate in the literature and caused some experts to doubt its existence altogether. The primary focus in this study is on the neurologic forms of TOS. However, for completeness and a better understanding of these neurologic manifestations, the vascular forms are also reviewed. Muscle Nerve 45: 780–795, 2012
Predictors of response to immunomodulation in patients with myasthenia gravis
Authors: Katzberg Hans D. , Barnett Carolina , Bril Vera
Published: November 2011

Introduction: Factors determining response to intravenous immunoglobulin (IVIg) and plasmapheresis in myasthenia gravis (MG) have not been evaluated systematically. Methods: This study included patients treated with IVIg (n = 63) or plasmapheresis (n = 42) from two trials evaluating IVIg vs. placebo or plasmapheresis in MG. Response was defined as improvement in the quantitative myasthenia gravis score (QMGS) of ≥3.5 points at day 14. Baseline clinical, electrophysiological, and immunological factors were analyzed as predictors. Results: Baseline QMGS, acetylcholine receptor antibody (AChRAb) positivity, single‐fiber electromyography (SFEMG) jitter, and percent abnormal pairs and percent blocking pairs were higher in responders than in non‐responders. Using multivariate logistic regression, the odds ratio for response was 13.0 (1.01–381.5) in QMGS 11–17 and 15.3 (1.34–414.3) in QMGS >17 compared with QMGS <11. Conclusions: Baseline QMGS, AChRAb positivity, and SFEMG parameters were more abnormal in patients who responded to treatment. Using multivariate regression, baseline QMGS remained as the only significant independent predictor of response. Muscle Nerve, 2012
Experimental muscle injury: Correlation between ultrasound and histological findings
Authors: JimÉnez‐Díaz Fernando , Jimena Ignacio , Luque Evelio , MendizÁbal Susana , Bouffard Antonio , JimÉnez‐Reina Luis , PeÑa JosÉ
Published: November 2011

Introduction:

In this study we correlated ultrasound findings with histological changes taking place during experimentally induced degeneration–regeneration in rat skeletal muscle.

Methods:

Gastrocnemius muscles were injected with mepivacaine, and the progress of the muscle injury was monitored by ultrasound from day 1 to day 20. Muscles were extracted on the same days for histological examination.

Results:

The degenerative phase was characterized by increased echogenicity in the injured area; thereafter, echogenicity gradually diminished during the regenerative phase, attaining normal levels by 20 days postinjection. By this stage, histological examination revealed that regeneration was complete. The heteroechoic texture observed from day 4 to day 10 appeared to reflect the coexistence of degenerative and regenerative processes.

Conclusions:

The results suggest that the degenerative and regenerative phases of muscle injury may be distinguished sonographically through differences in echogenicity and echotexture and, using Doppler ultrasound, differences in the degree of vascularization. Muscle Nerve, 2012
Ultrasonographic assessment of longitudinal median nerve and hand flexor tendon dynamics in carpal tunnel syndrome
Authors: Korstanje Jan‐Wiebe H. , Boer Marjan Scheltens‐De , Blok Joleen H. , Amadio Peter C. , Hovius Steven E.R. , Stam Henk J. , Selles Ruud W.
Published: November 2011

Introduction: Changes in subsynovial connective tissue (SSCT) in carpal tunnel syndrome (CTS) patients may result in altered dynamics; consequently, quantification of these dynamics might support objective diagnosis of CTS. Methods: We measured and compared longitudinal excursion of the flexor digitorum superficialis and profundus tendons, the median nerve, and the SSCT between the most and least affected hands of 51 CTS patients during extension‐to‐fist motion. Results: Median nerve and flexor digitorum superficialis tendon excursions in the most affected hands were smaller than in the least affected hands of the same patients, whereas the excursions of the flexor digitorum profundus were larger. Based on these excursions, logistic regression models classified between 67% and 86% of the hands correctly as having CTS. Conclusions: The altered hand dynamics in CTS patients may have implications for the pathophysiology and clinical evaluation of CTS, and ultrasound‐based classification models may further support the diagnosis of CTS. Muscle Nerve, 2012
Performance of bamboo plastic composites with hybrid bamboo and precipitated calcium carbonate fillers
Authors: Kim Birm‐June , Yao Fei , Han Guangping , Wu Qinglin
Published: November 2011

The influences of hybrid bamboo and precipitated calcium carbonate (PCC) fillers in a recycled polypropylene/polyethylene matrix on the properties of bamboo plastic composites were studied. Thermogravimetric and Fourier transform infrared analyses of both thermo‐mechanically refined bamboo fiber (RBF) and ground bamboo particle (GBP) showed relatively higher holocellulose content in RBF, and more effective silane grafting on the RBF surface. The raw PCC particles contained over 95% calcium carbonate, and had an agglomerated form consisting of particles with a mean diameter of about 1.2 microns. Compounding the PCC particles with the plastic resin helped separate and disperse them in the matrix. Measured flexural strength and modulus of PCC‐only‐filled composites increased significantly from 15 to 30% PCC content levels, while the tensile and impact strength of composites decreased with the addition of PCC. For composites with hybrid bamboo and PCC fillers, tensile and flexural moduli were improved with the increase of PCC content. After silane treatment, RBF‐filled composites showed noticeably increased mechanical properties compared with those of GBP‐filled composites. For modulus values, PCC–bamboo–polymer composites were 3–4 times higher than those of PCC–polymer composites at high PCC levels. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers
Effect of functionalized elastomer addition on mechanical and interfacial properties of poly (butylene terephthalate)/glass fiber composites
Authors: Deshmukh G.S. , Peshwe D.R. , Pathak S.U. , Ekhe J.D.
Published: November 2011

In this study the effect of incorporation of ethylene‐co‐glycidylmethacrylate (GMA)‐co‐n‐butyl acrylate (nBA) terpolymer with an epoxy functional group, on the mechanical performance of short glass fiber (SGF)/Poly (butylene terephthalate) (PBT) composites has been investigated. Tensile test showed that incorporation of rubber phase in PBT/SGF composites results in loss of strength. However impact measurement exhibited an increase in impact strength with an increase in rubber content. Tensile and impact properties are discussed in terms of interfacial shear strength and morphology of composites. Morphological observation by SEM revealed a thin layer of polymer adhering to the surface of glass fibers indicating that epoxy functional group in the modifier reacts with fiber surface and PBT matrix. This reactivity of epoxy functional group is also supported by FTIR observations. The composites are also analyzed for % crystallinity using DSC and a strong correlation is found to exist between interfacial shear strength and % crystallinity. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers
Disproportionality analysis for signal detection of implantable cardioverter–defibrillator‐related adverse events in the Food and Drug Administration Medical Device Reporting System
Authors: Duggirala Hesha J. , Herz Naomi D. , Caños Daniel Arthur , Sullivan Roberta A. , Schaaf Richard , Pinnow Ellen , Marinac‐Dabic Danica
Published: November 2011

Background

The Food and Drug Administration (FDA) became aware of lead fracture and inappropriate shock events related to Sprint Fidelis leads in January 2007. The manufacturer announced a voluntary market withdrawal in October 2007.

Aim

Our aim was to retrospectively evaluate this safety signal using disproportionality analysis to estimate whether disproportionality analysis could have detected this particular safety signal earlier than actually occurred.

Materials and Methods

The Manufacturer and User Facility Device Experience (MAUDE) database contains reports on device‐related adverse events, of which, FDA receives several hundred thousand every year. For each manufacturer, a list of the top lead brand names was ranked by frequency of reports. We used the Multi‐item Gamma Poisson Shrinker (MGPS) method for analysis. We isolated 11 top‐reported implantable cardioverter defibrillator (ICD) lead brand names. Using MGPS methodology, we calculated the one‐sided 95% lower confidence bound EB05 on the empirical Bayes geometric mean of the reporting ratio.

Results

We performed individual MGPS analysis for each of the top reported adverse events in 2006 for ICD leads. Fidelis had the highest EB05 scores for lead fractures and inappropriate shock.

Discussion

Through disproportionality analysis of the MAUDE database, we were able to identify known safety signals associated with the Medtronic Sprint Fidelis lead.

Conclusion

If utilized at the time, this disproportionality analysis would have identified signals earlier for lead fractures, oversensing, high impedance, and inappropriate shock. Copyright © 2011 John Wiley & Sons, Ltd.
Structure and properties of hydrophobic cationic poly(vinyl alcohol)
Authors: Wang Jie , Ye Lin
Published: November 2011

A new class of derivatives of poly(vinyl alcohol) (PVA) was prepared through hydrophobic cationic modification. The structure and composition of PVA grafted with glycidyl‐N‐alkyl‐N,N‐dimethyl‐ammonium chloride (DA) (PVA‐graft‐DA) was confirmed with Fourier transform infrared spectral analysis and 1H NMR spectral analysis. The stress‐strain curves of PVA‐graft‐DA samples all exhibited an elastic deformation stress plateau, and strain hardening behavior can be observed, indicating the transition of PVA from brittle fracture to ductile fracture. Compared with virgin PVA, the relaxation peak (Tg) of PVA‐graft‐DA shifted to a lower temperature. With increasing alkyl chain length and grafting ratio of DA, Tg decreased, and PVA‐graft‐DA exhibited a gradually decreasing storage modulus over the whole temperature range of testing due to the relatively weak intermolecular hydrogen bonding and increasing flexibility of molecular chains by introduction of long alkyl chains. PVA crystallites were not affected by grafting with DA, while the crystallization temperature and crystallinity of PVA were improved and the grain size decreased. On grafting with DA, the fracture surface of PVA changed from a smooth surface to regularly distanced striations, displaying much obvious character of tough fracture, indicating that appropriate intermolecular association of the hydrophobic groups facilitated the formation of physical entanglement of molecular chains to strengthen and toughen the PVA matrix. PVA‐graft‐DA showed a significant decreasing surface tension with polymer concentration, while the surface tension of PVA‐graft‐DA12 dropped most dramatically and declined with increasing grafting ratio of DA12, indicating improvement of the surface activity of PVA by introduction of hydrophobic alkyl chains and hydrophilic cationic groups. Copyright © 2011 Society of Chemical Industry
Governmental Stakeholder and Project Owner's Views on the Regulative Framework in Nuclear Projects
Authors: Sallinen Liisa , Ahola Tuomas , Ruuska Inkeri
Published: November 2011

This article aims at increasing the understanding of a specific type of stakeholder, namely governmental stakeholders who have significant influence over projects and base their influence on a regulative framework. Various parties in nuclear projects create their own interpretations of the framework. To understand why there are differences in these interpretations, we used three institutional elements: (1) laws and rules, (2) practices, and (3) values for analysis. This article uses interview data from a nuclear industry governmental stakeholder and a project owner. The results show that interpretations are not always coherent, and the incoherencies are clearest in the practice element.
Managing the Institutional Context for Projects
Authors: Morris Peter W. G. , Geraldi Joana
Published: November 2011

Project management is widely seen as delivering undertakings on time, on budget, and on scope. This conceptualization fails, however, to address the front end and its management. Addressing the front end moves the discipline to a second, more strategic level. This article proposes a third level of conceptualization: the institutional level, where management is focused on creating the conditions to support and foster projects, both in its parent organization and its external environment. Management here is done for and on the project rather than in or to it. We show that management at this level offers an enlarged research agenda and improvement in performance.
Electrochemically induced oxidative cyclization of 2,3‐dihydroxypyridine. Synthesis of a novel highly oxygenated heterocyclic compound
Authors: Varmaghani Fahimeh , Nematollahi Davood
Published: November 2011

Electrochemical oxidation of 2,3‐dihydroxypyridine in aqueous phosphate buffer solution at a glassy carbon electrode has been studied using cyclic voltammetry and controlled potential coulometry. The results indicate that oxidation of 2,3‐dihydroxypyridine on glassy carbon electrode shows an irreversible feature in aqueous solution. This data indicates that the electrochemically generated pyridindione is unstable and via an oxidative conversion pathway converts to a novel highly oxygenated heterocyclic compound. By means of the obtained electrochemical data, an efficient, one‐pot method for the synthesis of this heterocyclic compound based on the oxidative cyclization of 2,3‐dihydroxypyridine under green conditions, and in a good yield and purity is described. Copyright © 2011 John Wiley & Sons, Ltd.
Toward the discovery of new soft quasicrystals: From a numerical study viewpoint
Authors: Dotera Tomonari
Published: November 2011

This is a progress review of an emerging research front: soft quasicrystals including liquid crystalline dendrons, nanoparticles, mesoporous silica, colloids, ABC star and linear terpolymers, and even water and silicon. As an aid to readers, we explain the basics of quasicrystals developed in solid‐state physics: orders in quasicrystals, higher dimensional crystallography, approximants, phason randomness, and the origin of quasicrystal formation. Then we review some numerical studies from early to recent ones. Our main purpose is to elucidate how to construct quasicrystalline structures: The introduction of additional components or a new length‐scale is the key to discover new quasicrystals. As a case study, we describe our recent studies on ABC star terpolymer systems and present the results of simulations of dodecagonal polymeric quasicrystals. In the case of dodecagonal quasicrystals, one easily finds that the key is to search square‐triangle tiling structures with changing components. Application to photonic quasicrystals is reviewed as well. Our hope is that this review will contribute furthering quasicrystal chemistry. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012
Air and Ground Temperature Variations Observed along Elevation and Continentality Gradients in Southern Norway
Authors: Farbrot Herman , Hipp Tobias Florian , Etzelmüller Bernd , Isaksen Ketil , Ødegård Rune Strand , Schuler Thomas Vikhamar , Humlum Ole
Published: November 2011

The coupling between air and ground temperatures in the mountains of southern Norway was examined using 12 shallow boreholes drilled in August 2008. Three borehole arrays (at Juvvass, Jetta and Tron), each with boreholes at different elevations, were established along a continentality gradient. At the least continental site (Juvvass), the transect includes boreholes with shallow seasonal frost to continuous permafrost, while at Jetta and Tron, the arrays covered the transition from relatively deep seasonal frost to marginal permafrost. On the north slope of Tron, however, ground surface temperatures indicate more widespread permafrost conditions, apparently due to the negative thermal anomaly associated with an openwork block field. The surface offsets (mean ground surface temperature (MGST) minus mean air temperature (MAT)) ranged from < 1 °C for unvegetated wind‐scoured sites to up to 4.5 °C for sites with a thick, prolonged snow cover. Active‐layer thicknesses at the borehole sites close to the lower limit of mountain permafrost were up to 10 m in bedrock, even under a low thermal diffusivity sediment cover. The mean ground temperature at 10‐m depth differed significantly from the MGST, mainly due to the 3D thermal effects of the varying snow cover. Our air temperature measurements do not support the inference that the observed decrease in the lower elevational limit of mountain permafrost with continentality is mainly due to lower MAT. Rather, the pattern fits with an eastwards decrease in the lower limit of block fields and snowfall amounts. Copyright © 2011 John Wiley & Sons, Ltd.
Structural basis for extracellular interactions between calcitonin receptor‐like receptor and receptor activity‐modifying protein 2 for adrenomedullin‐specific binding
Authors: Kusano Seisuke , Kukimoto‐Niino Mutsuko , Hino Nobumasa , Ohsawa Noboru , Okuda Ken‐ichi , Sakamoto Kensaku , Shirouzu Mikako , Shindo Takayuki , Yokoyama Shigeyuki
Published: November 2011

The calcitonin receptor‐like receptor (CRLR), a class B GPCR, forms a heterodimer with receptor activity‐modifying protein 2 (RAMP2), and serves as the adrenomedullin (AM) receptor to control neovascularization, while CRLR and RAMP1 form the calcitonin gene‐related peptide (CGRP) receptor. Here, we report the crystal structures of the RAMP2 extracellular domain alone and in the complex with the CRLR extracellular domain. The CRLR–RAMP2 complex exhibits several intermolecular interactions that were not observed in the previously reported CRLR–RAMP1 complex, and thus the shape of the putative ligand‐binding pocket of CRLR–RAMP2 is distinct from that of CRLR–RAMP1. The CRLR–RAMP2 interactions were confirmed for the full‐length proteins on the cell surface by site‐specific photo‐crosslinking. Mutagenesis revealed that AM binding requires RAMP2 residues that are not conserved in RAMP1. Therefore, the differences in both the shapes and the key residues of the binding pocket are essential for the ligand specificity.
Characterization of as‐grown and adsorbate‐covered N‐polar InN surfaces using in situ photoelectron spectroscopy
Authors: Eisenhardt Anja , Himmerlich Marcel , Krischok Stefan
Published: November 2011

The surface electronic properties and adsorption behaviour of as‐grown and oxidized N‐polar InN films are characterized by photoelectron spectroscopy (XPS, UPS). The epitaxial growth of the InN layers was performed by plasma‐assisted molecular beam epitaxy on GaN/6H‐SiC(000‐1). After growth and in situ characterization the InN surfaces were exposed to molecular oxygen to evaluate the adsorption behaviour of O2 on N‐polar InN and to study its impact on the surface electronic properties of the III‐nitride material. The results are compared with studies on In‐polar InN on GaN/sapphire templates. The as‐grown N‐polar InN surface exhibits a pronounced surface state at a binding energy of ∼1.6 eV. The valence band minimum lies about 0.8–1.0 eV below the surface Fermi level. Additionally, the XPS core level binding energies for InN(000‐1) are reduced compared to InN(0001) films, indicating different surface band bending for clean N‐polar and In‐polar InN, respectively. The interaction of molecular oxygen with the InN(000‐1) surface leads to a downward band bending by 0.1 eV compared to the initial state. Additional adsorption of species from the residual gas of the UHV chamber increases the surface downward band bending. Furthermore two pronounced oxygen related states with an energy distance of ∼5 eV could be detected in the valence band region. The adsorbed oxygen results in an additional component in the N1s core level spectra, which is interpreted as formation of NOx bonds.
Global robust output regulation for a class of multivariable systems
Authors: Ping Zhaowu , Huang Jie
Published: November 2011

In this paper, we study the global robust output regulation problem for a class of multivariable nonlinear systems. The problem is first converted into a stabilization problem of an augmented system composed of the original plant and an internal model. The augmented system is a multi‐input system containing both dynamic uncertainty and time‐varying static uncertainty. By decomposing the multi‐input control problem into several single‐input control problems, we will solve the problem by solving several single‐input control problems via a recursive approach utilizing the changing supply function technique. The theoretical result is applied to the speed tracking control and load torque disturbance rejection problem of a surface‐mounted permanent magnet synchronous motor. Copyright © 2011 John Wiley & Sons, Ltd.
Surface science aspects of supramolecular conformation in elastin‐like polypeptides
Authors: Castle James E. , Salvi Anna Maria , Flamia Roberta , Satriano Giuseppina
Published: November 2011

Polypeptides can form helical fibres in aqueous media: potentially useful for the production of biocompatible fabric and yarns. A previous work has shown that fibre formation occurs readily with elastin‐like polypeptides constructed from hydrophobic amino acids, such as valine, glycine and leucine. However, elastin‐like polypeptides, when suspended in methyl alcohol, are observed to form globules and ‘string of bead’ structures. Thus, it seems probable that the interface energy is important. Interface energy is minimised by the formation of bonds extending from one phase to the other: a phenomenon that is central to adhesion science. We have looked for evidence of such bonding using XPS to study structures formed by poly(ValGlyGlyLeuGly). The structures formed were first characterised by atomic force microscopy. Differences were found between structures and spectra formed in either water or methanol. No evidence for the presence of unique bonds characterising the interface was found, but evidence was found for the influence of a water environment on the internal structure, suggesting that it is the increase in intermolecular bonding opportunities associated with the influence of water on the growth of fibres that is the thermodynamic driver for the observed transformation into fibre deposits. Copyright © 2011 John Wiley & Sons, Ltd.
Synergistic Control of Mesenchymal Stem Cell Differentiation by Nanoscale Surface Geometry and Immobilized Growth Factors on TiO2 Nanotubes
Authors: Park Jung , Bauer Sebastian , Pittrof Andreas , Killian Manuela S. , Schmuki Patrik , von der Mark Klaus
Published: November 2011

The aim of this study is to elucidate whether combined environmental signals provided by nanoscale topography and by growth factors control cell behavior of mesenchymal stem cells (MSCs) in a synergistic or simply additive manner. Chondrogenic and osteogenic differentiation of MSCs is studied on vertically aligned TiO2 nanotubes of size 15 and 100 nm with and without immobilized bone morphogenetic protein‐2 (BMP‐2). Although BMP‐2 coating stimulates both chondrogenic and osteogenic differentiation of MSCs, the response strongly depends on the surface nanoscale geometry of the BMP‐2‐coated nanotubes. Chondrogenic differentiation is strongly supported on 100 nm BMP‐2‐coated nanotubes, but not on 15 nm nanotubes, which induce spreading and de‐differentiation of chondrocytes. A similar response is observed with primary chondrocytes, which maintain their chondrogenic phenotype on BMP‐2‐coated 100 nm nanotubes, but de‐differentiate on 15 nm nanotubes. In contrast, osteogenic differentiation is greatly enhanced on 15 nm but not on 100 nm BMP‐2‐coated nanotubes as shown previously. Furthermore, covalent immobilization of BMP‐2 rescues MSCs from apoptosis occurring on uncoated 100 nm TiO2 nanotube surfaces. Thus, combined signals provided by BMP‐2 immobilized to a defined lateral nanoscale spacing geometry seem to contain environmental cues that are able to modulate a lineage‐specific decision of MSC differentiation and cell survival in a synergistic manner.
Co‐tunneling Enhancement of the Electrical Response of Nanoparticle Networks
Authors: Pauly Matthias , Dayen Jean‐François , Golubev Dimitry , Beaufrand Jean‐Baptiste , Pichon Benoit P. , Doudin Bernard , Bégin‐Colin Sylvie
Published: November 2011

A co‐tunneling charge‐transfer process dominates the electrical properties of a nanometer‐sized “slice” in a nanoparticle network, which results in universal scaling of the conductance with temperature and bias voltage, as well as enhanced spintronics properties. By designing two large (10 μm) electrodes with short (60 nm) separation, access is obtained to transport dominated by charge transfer involving “nanoslices” made of three nanoparticles only. Magnetic iron oxide nanoparticle networks exhibit a magnetoresistance ratio that is not reachable by tunneling or hopping processes, thereby illustrating how such a size‐matched planar device with dominant co‐tunneling charge‐transfer process is optimal for realizing multifunctional devices with enhanced change of conductance under external stimulus.
Delayed Photoelectron Transfer in Pt‐Decorated CdS Nanorods under Hydrogen Generation Conditions
Authors: Berr Maximilian J. , Vaneski Aleksandar , Mauser Christian , Fischbach Stefan , Susha Andrei S. , Rogach Andrey L. , Jäckel Frank , Feldmann Jochen
Published: November 2011

Noble‐metal‐decorated colloidal semiconductor nanocrystals are currently receiving significant attention for photocatalytic hydrogen generation. A detailed knowledge of the charge‐carrier dynamics in these hybrid systems under hydrogen generation conditions is crucial for improving their performance. Here, a transient absorption spectroscopy study is conducted on colloidal, Pt‐decorated CdS nanorods addressing this issue. Surprisingly, under hydrogen generation conditions (i.e., in the presence of the hole‐scavenger sodium sulfite), photoelectron transfer to the catalytically active Pt is slower than without the hole scavenger, where no significant hydrogen generation occurs. This unexpected behavior can be explained by different degrees of localization of the electron wavefunction in the presence and absence of holes on the nanorods, which modify the electron transfer rates to the Pt. The results show that solely optimizing charge transfer rates in photocatalytic nanosystems is no guarantee of improved performance. Instead, the collective Coulomb interaction‐mediated electron–hole dynamics need to be considered.
New Triblock Copolymer Templates, PEO‐PB‐PEO, for the Synthesis of Titania Films with Controlled Mesopore Size, Wall Thickness, and Bimodal Porosity
Authors: Ortel Erik , Fischer Anna , Chuenchom Laemthong , Polte Jörg , Emmerling Franziska , Smarsly Bernd , Kraehnert Ralph
Published: November 2011

The synthesis and properties of a series of new structure‐directing triblock copolymers with PEO‐PB‐PEO structure (PEO = poly(ethylene oxide) and PB = polybutadiene) and their application as superior pore‐templates for the preparation of mesoporous titania coatings are reported. Starting from either TiCl4 or from preformed TiO2 nanocrystalline building blocks, mesoporous crystalline titanium oxide films with a significant degree of mesoscopic ordered pores are derived, and the pore size can be controlled by the molecular mass of the template polymer. Moreover, the triblock copolymers form stable micelles already at very low concentration, i.e., prior to solvent evaporation during the evaporation‐induced self‐assembly process (EISA). Consequently, the thickness of pore walls can be controlled independently of pore size by changing the polymer‐to‐precursor ratio. Thus, unprecedented control of wall thickness in the structure of mesoporous oxide coatings is achieved. In addition, the micelle formation of the new template polymers is sufficiently distinct from that of typical commercial PPO‐PEO‐PPO polymers (Pluronics; PPO = poly(propylene oxide)), so that a combination of both polymers facilitates bimodal porosity via dual micelle templating.
In Vivo NIR Fluorescence Imaging, Biodistribution, and Toxicology of Photoluminescent Carbon Dots Produced from Carbon Nanotubes and Graphite
Authors: Tao Huiquan , Yang Kai , Ma Zhen , Wan Jianmei , Zhang Youjiu , Kang Zhenhui , Liu Zhuang
Published: November 2011

Oxidization of carbon nanotubes by a mixed acid has been utilized as a standard method to functionalize carbon nanomaterials for years. Here, the products obtained from carbon nanotubes and graphite after a mixed‐acid treatment are carefully studied. Nearly identical carbon dot (Cdot) products with diameters of 3–4 nm are produced using this approach from a variety of carbon starting materials, including single‐walled carbon nanotubes, multiwalled carbon nanotubes, and graphite. These Cdots exhibit strong yellow fluorescence under UV irradiation and shifted emission peaks as the excitation wavelength is changed. In vivo fluorescence imaging with Cdots is then demonstrated in mouse experiments, by using varied excitation wavelengths including some in the near‐infrared (NIR) region. Furthermore, in vivo biodistribution and toxicology of those Cdots in mice over different periods of time are studied; no noticeable signs of toxicity for Cdots to the treated animals are discovered. This work provides a facile method to synthesize Cdots as safe non‐heavy‐metal‐containing fluorescent nanoprobes, promising for applications in biomedical imaging.
Bone Marrow-Derived Mesenchymal Stromal Cells are Attracted by Multiple Myeloma Cell-Produced Chemokine CCL25 and Favor Myeloma Cell Growth in Vitro and In Vivo
Authors: Xu Song , Menu Eline , Becker Ann De , Van Camp Ben , Vanderkerken Karin , Van Riet Ivan
Published: November 2011

Multiple myeloma (MM) is a malignancy of terminally differentiated plasma cells that are predominantly localized in the bone marrow (BM). Mesenchymal stromal cells (MSCs) give rise to most BM stromal cells that interact with MM cells. However, the direct involvement of MSCs in the pathophysiology of MM has not been well addressed. In this study, in vitro and in vivo migration assays revealed that MSCs have tropism toward MM cells, and CCL25 was identified as a major MM cell-produced chemoattractant for MSCs. By coculture experiments, we found that MSCs favor the proliferation of stroma-dependent MM cells through soluble factors and cell to cell contact, which was confirmed by intrafemoral coengraftment experiments. We also demonstrated that MSCs protected MM cells against spontaneous and Bortezomib-induced apoptosis. The tumor-promoting effect of MSCs correlated with their capacity to enhance AKT and ERK activities in MM cells, accompanied with increased expression of CyclinD2, CDK4, and Bcl-XL and decreased cleaved caspase-3 and poly(ADP-ribose) polymerase expression. In turn, MM cells upregulated interleukin-6 (IL-6), IL-10, insulin growth factor-1, vascular endothelial growth factor, and dickkopf homolog 1 expression in MSCs. Finally, infusion of in vitro-expanded murine MSCs in 5T33MM mice resulted in a significantly shorter survival. MSC infusion is a promising way to support hematopoietic recovery and to control graft versus host disease in patients after allogeneic hematopoietic stem cell transplantation. However, our data suggest that MSC-based cytotherapy has a potential risk for MM disease progression or relapse and should be considered with caution in MM patients.

Disclosure of potential conflicts of interest is found at the end of this article.
Model predictive control for wind turbines with distributed active flaps: incorporating inflow signals and actuator constraints
Authors: Barlas T.K. , van der Veen G.J. , van Kuik G.A.M.
Published: November 2011

This paper describes the implementation of system identification and controller design techniques using model predictive control (MPC) for wind turbines with distributed active flaps for load control. An aeroservoelastic model of the 5 MW NREL/Upwind reference wind turbine, implemented in the code DU_SWAMP, is used in an industry‐based MPC controller design cycle, involving the use of dedicated system identification techniques. The novel multiple‐input multiple‐output MPC controllers, which incorporate flap actuator constraints and the use of local inflow measurement signals, are designed and implemented for various operating points. The controllers are evaluated in standard power production load cases and fatigue load reductions up to 27.3% are achieved. The distributed flaps controller scheme is also compared with simpler single‐flap single‐input single‐output and individual pitch controller schemes. Copyright © 2011 John Wiley & Sons, Ltd.
Coordinated control of series‐connected offshore wind park based on matrix converters
Authors: Garcés A. , Molinas M.
Published: November 2011

Optimization and reliability are two important aspects in design and operation of wind parks either for offshore as for onland emplacements. However, offshore locations demand conscientious effort in optimizing the size and the weight of each component in the energy conversion system because of the high investment and maintenance costs related with the supporting structures and transportation respectively. Achieving these two objectives requires the combination of different optimization stages, which consider a suitable design of the entire conversion system with innovative and more eﬃcient power electronic devices, optimized topology of the offshore grid and customized control strategies for optimizing the operation of the park.

This paper presents an energy conversion concept for wind turbines on the basis of a reduced matrix converter (RMC) that will enable series direct current architecture in offshore wind parks thus preventing the need for offshore platforms. The RMC is built with bidirectional semiconductors that give reduced losses because of both superior topology and more eﬃcient semiconductors. The proposed conversion topology is tested in stationary state and transient operation. In addition to operational features of the concept, control and operation of a wind park with several turbines are presented.

Dynamic operation of the turbine as well as the high‐voltage direct current transmission line effects are considered. Three types of models are therefore developed. First, an accurate and detailed model for analyzing one single turbine with the converter operated at high‐frequency switching is presented. This model considers a new modulation for the RMC. A second and simpliﬁed model is used for small signal analysis. This model permits to simulate several series‐connected cluster during transient. Finally, an optimal direct current load ﬂow model is used for evaluating stationary state operation.

Results show the technical feasibility of the proposed concept and their advantages over conventional topologies. The paper also discusses the technological challenges that this type of offshore grid architecture will bring. Copyright © 2011 John Wiley & Sons, Ltd.
A model of ice throw trajectories from wind turbines
Authors: Biswas Sumita , Taylor Peter , Salmon Jim
Published: November 2011

A model of the trajectories of ice fragments thrown from a rotating wind turbine blade is used to estimate the ground impact locations that could occur under different scenarios. Wind speed, ejection position on the blade and turbine rotation rate all play a role in determining the impact point, as well as mass, density and drag coefficient of the ice fragment. For ‘compact’ ice fragments, the trajectory depends on the combination CDA∕M where CD is the drag coefficient, A is the frontal area and M the mass of the ice fragment. Sensitivity tests show that ice fragments can travel further laterally for low CD and further downwind for high CD. For plate‐like fragments, aerodynamic lift can increase the distance travelled if the plate maintains an orientation to maximize lift. Although this may be a relatively rare event, we provide an example where a 1 kg plate‐like fragment could travel up to 350 m from the base of the turbine. Copyright © 2011 John Wiley & Sons, Ltd.
Engineering Yarrowia lipolytica to express secretory invertase with strong FBA1IN promoter
Authors: Hong Seung‐Pyo , Seip John , Walters‐Pollak Dana , Rupert Ross , Jackson Raymond , Xue Zhixiong , Zhu Quinn
Published: November 2011

Oleaginous yeast Yarrowia lipolytica is an important host for the production of lipid‐derived compounds or heterologous proteins. Selection of strong promoters and effective expression systems is critical for heterologous protein secretion. To search for a strong promoter in Y. lipolytica, activities of FBA1, TDH1 and GPM1 promoters were compared to that of TEF1 promoter by constructing GUS reporter fusions. The FBA1 promoter activity was 2.2 and 5.5 times stronger than the TDH1 and GPM1 promoters, respectively. The FBA1IN promoter (FBA1 sequence of −826 to +169) containing an intron (+64 to +165) showed five‐fold higher expression than the FBA1 promoter (−831 to −1). The transcriptional enhancement by the 5′‐region within the FBA1 gene was confirmed by GPM1::FBA1 chimeric promoter construction. Using the strong FBA1IN promoter, four different S. cerevisiae SUC2 expression cassettes were tested for the SUC+ phenotype in Y. lipolytica. Functional invertase secretion was facilitated by the Xpr2 prepro‐region with an additional 13 amino acids of mature Xpr2, or by the native Suc2 signal sequence. However, these two secretory signals in tandem, or the mature Suc2 with no secretory signal, did not direct secretion of functional invertase. Unlike previously reported Y. lipolytica SUC+ strains, our engineered stains secreted most of invertase into the medium. Copyright © 2011 John Wiley & Sons, Ltd.
Behavioral autonomy age expectations among Mexican‐origin mother–daughter dyads: An examination of within‐group variability
Authors: Bámaca‐Colbert Mayra Y. , Umaña‐Taylor Adriana J. , Espinosa‐Hernández Graciela , Brown Ashley M.
Published: November 2011

This study examined differences in behavioral autonomy age expectations between Mexican‐origin mothers and their adolescent daughters (N = 319 dyads); variability in behavioral autonomy age expectations as a function of nativity and maternal educational attainment also was examined. Findings indicated significant differences between mothers and daughters, such that mothers reported later expectations for the timing of behavioral autonomy than did daughters. Follow‐up analyses indicated that findings appeared to be driven by maternal nativity, with dyads comprised of Mexico‐born mothers reporting the latest age expectations for behavioral autonomy when compared with dyads comprised of U.S. born mothers. Findings underscore the need to examine normative development among Latino adolescents and their families with a specific focus on how sociocultural characteristics can contribute to within‐family differences.
Clinical and Spatiotemporal Gait Effects of Canes in Hip Osteoarthritis
Authors: Fang Meika A. , Heiney Constance , Yentes Jennifer M. , Harada Nancy D. , Masih Sulabha , Perell‐Gerson Karen L.
Published: November 2011

Objective

To investigate the effects of cane use on spatiotemporal gait parameters, pain, and function in adults with hip osteoarthritis (OA).

Design

Prospective observational study.

Setting

An academic tertiary Veterans Affairs Healthcare Center.

Participants

Thirteen adults with symptomatic hip OA and 13 healthy adults.

Methods

We undertook gait analysis in all subjects with an optoelectronic camera system. Pain, stiffness, and physical function in subjects with hip OA were assessed with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC).

Main Outcome Measurements

Baseline spatiotemporal measures of unaided gait were obtained for healthy subjects. Baseline and 4‐week spatiotemporal gait parameters were assessed for hip OA subjects while they walked with and without a cane. Participants with hip OA completed the WOMAC at baseline and after 4 weeks of cane use.

Results

At baseline when walking unaided, the subjects with hip OA (age range 60‐75 years) had a significantly slower gait velocity, shorter affected limb stride length, and longer double‐stance time compared with healthy control subjects. When walking with a cane, they had a reduction in gait velocity (P < .05) caused by a decrease in cadence (P < .05) compared with walking unaided. After 4 weeks of cane use, the participants with hip OA demonstrated significant improvements in gait velocity (P < .05) and double‐stance time (P < .05) when walking with a cane in comparison with baseline data. There was no improvement in pain and function after 4 weeks of cane use, a period in which only approximately 60% of the hip OA subjects used the cane 6 or more times per week.

Conclusions

Initial use of a cane led to decreased gait velocity and cadence in people with hip OA compared with walking unaided. This difference in gait velocity diminished after they practiced walking with the cane. Inconsistent use of the cane may have contributed to the lack of improvement in the subjects' hip OA pain and function.