bluuebunny/crossref_metadata_2025 huggingface dataset:
Long‐Wavelength Photolysis of Amino Acid 6‐(Methoxy‐2‐oxo‐2H‐naphtho[1,2‐b]pyran‐4‐yl)methyl Esters
Authors: Piloto Ana M. , Soares Ana M. S. , Hungerford Graham , Costa Susana P. G. , Gonçalves M. Sameiro T.
Published: August 2011

(6‐Methoxy‐2‐oxo‐2H‐naphtho[1,2‐b]pyran‐4‐yl)methyl esters of valine or phenylalanine as model bifunctional molecules were synthesised to assess its applicability as a photocleavable protecting group for solution phase organic synthesis and in caging applications at longer wavelengths. The behaviour of the corresponding derivatives towards photolysis was evaluated by irradiation at 350 and 419 nm in a mixture of HEPES buffer and acetonitrile or methanol in a photochemical reactor, followed by HPLC/UV monitoring. Time‐resolved fluorescence measurements were used to elucidate the dynamics.
Impact of subsurface rock fragments on runoff and interrill soil loss from cultivated soils
Authors: Smets T. , López‐Vicente M. , Poesen J.
Published: August 2011

Field and laboratory studies have indicated that rock fragments in the topsoil may have a large impact on soil properties, soil quality, hydraulic, hydrological and erosion processes. In most studies, the rock fragments investigated still remain visible at the soil surface and only properties of these visible rock fragments are used for predicting runoff and soil loss. However, there are indications that rock fragments completely incorporated in the topsoil could also significantly influence the percolation and water distribution in stony soils and therefore, also infiltration, runoff and soil loss rates. Therefore, in this study interrill laboratory experiments with simulated rainfall for 60 min were conducted to assess the influence of subsurface rock fragments incorporated in a disturbed silt loam soil at different depths below the soil surface (i.e. 0.001, 0.01, 0.05 and 0.10 m), on infiltration, surface runoff and interrill erosion processes for small and large rock fragment sizes (i.e. mean diameter 0.04 and 0.20 m, respectively). Although only small differences in infiltration rate and runoff volume are observed between the soil without rock fragments (control) and the one with subsurface rock fragments, considerable differences in total interrill soil loss are observed between the control treatment and both contrasting rock fragments sizes. This is explained by a rapid increase in soil moisture in the areas above the rock fragments and therefore a decrease in topsoil cohesion compared with the control soil profile. The observed differences in runoff volume and interrill soil loss between the control plots and those with subsurface rock fragments is largest after a cumulative rainfall (Pcum) of 11 mm and progressively decreases with increasing Pcum. The results highlight the impacts and complexity of subsurface rock fragments on the production of runoff volume and soil loss and requires their inclusion in process‐based runoff and erosion models. Copyright © 2011 John Wiley & Sons, Ltd.
Spectral and power efficiency of IEEE802.11n MIMO‐OFDM WLAN systems using space‐multimode‐polarization diversity compact stacked circular microstrip antenna arrays
Authors: Yavanoğlu A. , Ertuğ Ö.
Published: August 2011

Recent developments in wireless communication systems in indoor environments require high data rates and high transmission qualities especially for multimedia applications in wireless local area network (WLAN) systems. The support of high data rate multiple‐input multiple‐output (MIMO) spatial‐multiplexing communication in orthogonal frequency‐division multiplexing WLAN systems conforming to IEEE802.11n standard requires the use of compact antennas with low correlation ports. In this paper, we analyse a MIMO array consisting of higher‐order space‐multimode‐polarization diversity stacked circular microstrip patch uniform linear antenna arrays (SMP‐SCP‐ULAs) to exploit SMP diversity for use in WLAN systems. Using higher number of antenna ports in lower space and low cross‐polar discrimination values between each transmit and receive antenna, SMP‐SCP‐ULA yields higher multiplexing gain and satisfies more restrictive size constraints in clustered MIMO systems. The performance gains of higher‐order modal SMP‐SCP‐ULA are presented in terms of modal correlation, ergodic spectral efficiency, average bit error rate and compactness gain with respect to dipole and circular microstrip patch uniform linear arrays. Copyright © 2011 John Wiley & Sons, Ltd.
CXCR4 signaling regulates remyelination by endogenous oligodendrocyte progenitor cells in a viral model of demyelination
Authors: Carbajal Kevin S. , Miranda Juan L. , Tsukamoto Michelle R. , Lane Thomas E.
Published: August 2011

Following intracranial infection with the neurotropic JHM strain of mouse hepatitis virus (JHMV), susceptible mice will develop widespread myelin destruction that results in pathological and clinical outcomes similar to those seen in humans with the demyelinating disease Multiple Sclerosis (MS). Partial remyelination and clinical recovery occurs during the chronic phase following control of viral replication yet the signaling mechanisms regulating these events remain enigmatic. Here we report the kinetics of proliferation and maturation of oligodendrocyte progenitor cells (OPCs) within the spinal cord following JHMV‐induced demyelination and that CXCR4 signaling contributes to the maturation state of OPCs. Following treatment with AMD3100, a specific inhibitor of CXCR4, mice recovering from widespread demyelination exhibit a significant (P < 0.01) increase in the number of OPCs and fewer (P < 0.05) mature oligodendrocytes compared with HBSS‐treated animals. These results suggest that CXCR4 signaling is required for OPCs to mature and contribute to remyelination in response to JHMV‐induced demyelination. To assess if this effect is reversible and has potential therapeutic benefit, we pulsed mice with AMD3100 and then allowed them to recover. This treatment strategy resulted in increased numbers of mature oligodendrocytes, enhanced remyelination, and improved clinical outcome. These findings highlight the possibility to manipulate OPCs in order to increase the pool of remyelination‐competent cells that can participate in recovery. © 2011 Wiley‐Liss, Inc.
Synthesis of new functionalized mono‐ and bisorganophosphorus acids and their derivatives with unsaturated and aromatic fragments
Authors: Prishchenko Andrey A. , Livantsov Mikhail V. , Novikova Olga P. , Livantsova Ludmila I. , Petrosyan Valery S.
Published: August 2011

Convenient procedures for the synthesis of functionalized mono‐ and bisorganophosphorus acids and their derivatives with unsaturated and aromatic fragments, starting from the available derivatives of trivalent phosphorus acids, unsaturated and aromatic aldehydes, and carboxylic acid chlorides, are proposed, and some properties of the new unsaturated organophosphorus compounds are presented. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 23:32–40, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20749
Teasing apart tangrams: Testing hippocampal pattern separation with a collaborative referencing paradigm
Authors: Duff Melissa C. , Warren David E. , Gupta Rupa , Vidal Juan Pablo Benabe , Tranel Daniel , Cohen Neal J.
Published: August 2011

The hippocampus and the medial temporal lobe cortex [medial temporal lobe cortices (MTLC)] both contribute to long‐term memory. Although their contributions are thought to be dissociable, the nature of the representations that each region supports remains unclear. The Complementary Learning Systems (CLS) modeling approach suggests that hippocampus represents overlapping information in a sparser and therefore more separated fashion than MTLC. We tested this prediction using a collaborative referencing paradigm whereby hippocampal amnesic patients and a partner work together to develop and use unique labels for a set of abstract visual stimuli (tangrams) across extended interactions. Previously, we reported that amnesic patients demonstrate intact learning when the tangrams are conceptually dissimilar. Here, we manipulated the degree of visual similarity; half of the stimuli were dissimilar to one another (e.g., camel and giraffe), and half were similar (e.g., birds). We hypothesized that while patients would have little difficulty with the dissimiliar tangrams (quickly arriving at unique and concise labels), they would be unable to rapidly form distinct representations of highly similar visual patterns. Consistent with this prediction, patients and both healthy and brain‐damaged comparison participants showed similar rates of learning for dissimilar tangrams, but the similar tangrams proved more difficult for hippocampal patients as reflected in the greater number of words they used to describe each similar card. This result supports the CLS model's central claim of hippocampal specialization for pattern separation and suggests that our collaborative referencing paradigm may be a useful tool for observing extended encoding of complex representations. © 2011 Wiley Periodicals, Inc.
Does Children's Colour Use Reflect the Emotional Content of their Drawings?
Authors: Crawford Emily , Gross Julien , Patterson Tess , Hayne Harlene
Published: August 2011

When children draw in clinical contexts, clinicians sometimes rely on children's colour use to make inferences about their emotional reaction to the subject of the drawing. Here, we examined whether children use colour to portray emotion in their drawings. In Experiment 1, children indicated their colour preferences and then coloured in outlines of figures characterized as nasty or nice. Children also drew complex, multi‐coloured pictures about their own happy or sad experiences. In Experiment 2, hospitalized children drew about being worried or scared in hospital and about their positive experiences. In both experiments, we examined the relation between children's colour use and their colour preferences. Three‐ to 10‐year‐old children used more preferred colours to colour in the nice outline. Although they were more likely to use non‐preferred colours to colour in the nasty outline, they tended to used a mix of preferred and non‐preferred colours. When both normal and hospitalized children produced drawings about positive and negative events, there was no relation between children's colour choices and their colour preferences; children primarily used preferred colours. These data suggest that clinicians should exercise extreme caution when interpreting the meaning of colour in children's drawings. Copyright © 2011 John Wiley & Sons, Ltd.
Mitochondrial DNA mutations in respiratory complex‐I in never‐smoker lung cancer patients contribute to lung cancer progression and associated with EGFR gene mutation
Authors: Dasgupta Santanu , Soudry Ethan , Mukhopadhyay Nitai , Shao Chunbo , Yee John , Lam Stephan , Lam Wan , Zhang Wei , Gazdar Adi F , Fisher Paul B , Sidransky David
Published: August 2011

Mitochondrial DNA (mtDNA) mutations were reported in different cancers. However, the nature and role of mtDNA mutation in never‐smoker lung cancer patients including patients with epidermal growth factor receptor (EGFR) and KRAS gene mutation are unknown. In the present study, we sequenced entire mitochondrial genome (16.5 kb) in matched normal and tumors obtained from 30 never‐smoker and 30 current‐smoker lung cancer patients, and determined the mtDNA content. All the patients' samples were sequenced for KRAS (exon 2) and EGFR (exon 19 and 21) gene mutation. The impact of forced overexpression of a respiratory complex‐I gene mutation was evaluated in a lung cancer cell line. We observed significantly higher (P = 0.006) mtDNA mutation in the never‐smokers compared to the current‐smoker lung cancer patients. MtDNA mutation was significantly higher (P = 0.026) in the never‐smoker Asian compared to the current‐smoker Caucasian patients' population. MtDNA mutation was significantly (P = 0.007) associated with EGFR gene mutation in the never‐smoker patients. We also observed a significant increase (P = 0.037) in mtDNA content among the never‐smoker lung cancer patients. The majority of the coding mtDNA mutations targeted respiratory complex‐I and forced overexpression of one of these mutations resulted in increased in vitro proliferation, invasion, and superoxide production in lung cancer cells. We observed a higher prevalence and new relationship between mtDNA alterations among never‐smoker lung cancer patients and EGFR gene mutation. Moreover, a representative mutation produced strong growth effects after forced overexpression in lung cancer cells. Signature mtDNA mutations provide a basis to develop novel biomarkers and therapeutic strategies for never‐smoker lung cancer patients. J. Cell. Physiol. 227: 2451–2460, 2012. © 2011 Wiley Periodicals, Inc.
Caveolin‐1 orchestrates fibroblast growth factor 2 signaling control of angiogenesis in placental artery endothelial cell caveolae
Authors: Feng Lin , Liao Wu‐Xiang , Luo Quan , Zhang Hong‐Hai , Wang Wen , Zheng Jing , Chen Dong‐Bao
Published: August 2011

Fibroblast growth factor (FGF) receptor 1 (FGFR1) protein was expressed as the long and short as well as some truncated forms in ovine fetoplacental artery ex vivo and in vitro. Upon FGF2 stimulation, both the long and short FGFR1s were tyrosine phosphorylated and the PI3K/AKT1 and ERK1/2 pathways were activated in a concentration‐ and time‐ dependent manner in ovine fetoplacental artery endothelial (oFPAE) cells. Blockade of the PI3K/AKT1 pathway attenuated FGF2‐stimulated cell proliferation and migration as well as tube formation; blockade of the ERK1/2 pathway abolished FGF2‐stimulated tube formation and partially inhibited cell proliferation and did not alter cell migration. Both AKT1 and ERK1/2 were co‐fractionated with caveolin‐1 and activated by FGF2 in the caveolae. Disruption of caveolae by methyl‐β‐cyclodextrin inhibited FGF2 activation of AKT1 and ERK1/2. FGFR1 was found in the caveolae where it physically binds to caveolin‐1. FGF2 stimulated dissociation of FGFR1 from caveolin‐1. Downregulation of caveolin‐1 significantly attenuated the FGF2‐induced activation of AKT1 and ERK1/2 and inhibited FGF2‐induced cell proliferation, migration and tube formation in oFPAE cells. Pretreatment with a caveolin‐1 scaffolding domain peptide to mimic caveolin‐1 overexpression also inhibited these FGF2‐induced angiogenic responses. These data demonstrate that caveolae function as a platform for regulating FGF2‐induced angiogenesis through spatiotemporally compartmentalizing FGFR1 and the AKT1 and ERK1/2 signaling modules; the major caveolar structural protein caveolin‐1 interacts with FGFR1 and paradoxically regulates FGF2‐induced activation of PI3K/AKT1 and ERK1/2 pathways that coordinately regulate placental angiogenesis. J. Cell. Physiol. 227: 2480–2491, 2012. © 2011 Wiley Periodicals, Inc.
Ultra‐performance liquid chromatography coupled to mass spectrometry as a sensitive and powerful technology for metabolomic studies
Authors: Wang Xijun , Sun Hui , Zhang Aihua , Wang Ping , Han Ying
Published: August 2011

Metabolomics is the comprehensive assessment of endogenous metabolites of a biological system. These large‐scale analyses of metabolites are intimately bound to advancements in ultra‐performance liquid chromatography–electrospray (UPLC) technologies and have emerged in parallel with the development of novel mass analyzers and hyphenated techniques. Recently, the combination of UPLC with MS covers a number of polar metabolites, thus enlarging the number of detected analytes in the widely used separation sciences. This technology has rapidly been accepted by the analytical community and is being gradually applied to various fields such as metabolomics and traditional Chinese medicine (TCM). Given the power of the technology, metabolomics has become increasingly popular in drug development, molecular medicine, traditional medicine and other biotechnology fields, since it profiles directly the phenotype and changes thereof in contrast to other “‐omics” technologies. Hyphenated UPLC/MS technique is becoming a useful tool in the study of body fluids, represents a promising hyphenated microseparation platform in metabolomics and has a strong potential to contribute to disease diagnosis. This review describes the applications of UPLC/MS in metabolomic research, and comparison role of HPLC/MS, NMR and GC/MS, highlights its advantages and limitations with certain characteristic examples in the life and TCM sciences.
Thermoresponsive Gene Carriers Based on Polyethylenimine‐graft‐Poly[oligo(ethylene glycol) methacrylate]
Authors: Zhang Rui , Wang Yang , Du Fu‐Sheng , Wang Ying‐Li , Tan Ying‐Xia , Ji Shou‐Ping , Li Zi‐Chen
Published: August 2011

A family of thermoresponsive cationic copolymers (TCPs) that contain branched PEI 25 K as the cationic segment and poly(MEO2MA‐co‐OEGMA475) as the thermosensitive block (TP) is prepared. The DNA binding capability, physicochemical properties, and biological performance of the TCPs are studied. All of these TCPs can condense DNA to form polyplexes with diameters of 150–300 nm and zeta potentials of 7–32 mV at N/P ratios between 12 and 36. The length of TP block is a key factor for shielding the positive surface charge of the polyplexes and protecting them against protein adsorption. TCPs with a higher TP content have a lower cytotoxicity while the best transfection performance is achieved by the TCPs with longest TP length, reaching a level of the intact PEI 25 K in the presence of serum.

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Corrosion behavior of 2A12 aluminum alloy in neutral salt spray environment with different Al‐clad removing processes
Authors: Liu H. C. , Xu H. P. , Zhu L. Q. , Liu J. Z. , Ye X. B. , Hu B. R.
Published: August 2011

In the process of assembling and machining, the aluminum alloy components will directly expose to aggressive environment once Al‐clad is destroyed. As such, it is meaningful to investigate the corrosion behavior of 2A12 aluminum alloy in neutral salt spray environment after removing Al‐clad coating with different processes. In this work, the corrosion behaviors of the aluminum alloy were evaluated by the changes in morphology, composition, and maximum mean corrosion depth. The results show that the corrosion rate of 2A12 aluminum alloy was very high in the first 24 h, and then decreased with test duration. Among all the Al‐clad removing processes, the one at higher temperature (90–100 °C) for shorter time (3–4 min) exhibit the best performance in the presence of inhibitor and sanding. The three possible reasons include effect of inhibitor adsorbing, role of sanding, impact of higher temperature, and shorter time.
Corrosion behavior of low‐alloy steel in the presence of Desulfovibrio caledoniensis
Authors: Cetin D. , Aksu M. L.
Published: August 2011

Sulfate‐reducing bacteria (SRB) are shown to be common inhabitants of oil reservoirs. Desulfovibrio caledoniensis isolated from a production well was used in this study. After an incubation period of 1 month with the SRB culture, two layers of corrosion products with different compositions were detected on the test coupons. The Tafel plots showed that the corrosion potential exhibited a cathodic shift and the corrosion rates increased with the incubation time. The analysis of the Nyquist diagrams revealed that the diffusion process begins to dominate with time in bacteria containing medium. These results are in good accordance with the Tafel data.
Microbiologically influenced corrosion of X60 carbon steel in CO2‐saturated oilfield flooding water
Authors: Fan M.‐M. , Liu H.‐F. , Dong Z.‐H.
Published: August 2011

The corrosion behavior of X60 carbon steel in CO2‐saturated oilfield flooding water inoculated with sulfate‐reducing bacteria (SRB) was investigated using polarization curves and electrochemical impedance spectroscopy (EIS). With the propagation of SRB in the flooding water, the pH values of flooding water increased quickly in the initial 2 days and remained relatively steady during the later stage. Polarization curves showed that the corrosion current density decreased during the first 10 days due to the protection of corrosion products and SRB‐biofilms, and then increased possibly due to the partial detachment of the corrosion products and the biofilms. EIS analysis also showed that the charge transfer resistance increased initially and then decreased with exposure time. In the beginning of corrosion, the anodic dissolution of X60 steel was dominated by CO2. After the formation of SRB‐biofilms, part of FeCO3 corrosion products was converted to incompact FeS precipitates by SRB bio‐mineralization. Thus, the dispersed iron sulfide in SRB‐biofilms and X60 steel base may constitute a galvanic couple, accelerating the localized corrosion of the steel base in the flooding water.
Reactivity Ratio Estimation from Cumulative Copolymer Composition Data
Authors: Kazemi Niousha , Duever Thomas A. , Penlidis Alexander
Published: August 2011

The goal is to present an alternative technique for reactivity ratio estimation in copolymerization. Typically, reactivity ratios are estimated using the instantaneous copolymer composition equation, based on low conversion copolymer composition data. However, using experimental data from the full copolymerization trajectory would, in principle, be more advantageous, and shy away from commonly used restrictive assumptions. Estimation using cumulative copolymerization data and models eliminates the difficulties associated with stopping reactions at low conversion, while one gains to study the full polymerization trajectory. The error‐in‐variables‐model (EVM) method is used for parameter estimation. Two cumulative model forms, the analytical integration of the differential composition equation and the one resulting from the direct numerical integration of this equation, are employed. Using these two types of models improves the reactivity ratio estimation and, in particular, the latter model form is a more reliable and direct method of estimating reactivity ratios.

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A Kinetic Investigation of Removal of Residual Monomers From Polymer LatexesViaPost‐polymerization and Nitrogen Stripping Methods
Authors: Kechagia Zoi , Kammona Olga , Pladis Prokopis , Alexopoulos Aleck H. , Kiparissides Costas
Published: August 2011

In the present study, a comprehensive experimental investigation on the removal of residual monomers and other volatile organic compounds (VOCs) from polymer latexesviapost‐polymerization and nitrogen stripping is reported. Both techniques are applied to poly(methyl methacrylate) (PMMA), poly(butyl acrylate) (PBuA), and poly(methyl methacrylate/butyl acrylate) P(MMA/BuA) latexes. The effects of various process parameters (e.g., temperature, oxidant and reductant types and concentrations, addition time of the oxidant/reductant redox system for the post‐polymerization process and nitrogen flow rate, agitation rate, and temperature for the physical stripping process) and latex properties (e.g., particle size, wt.‐% of polymer solids and copolymer composition) on the monomer removal process efficiency are experimentally assessed. Finally, the two methods are applied in a simultaneous or sequential mode, to further improve the VOCs removal efficiency.

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FE/BE coupling for an acoustic fluid–structure interaction problem. Residual a posteriori error estimates
Authors: Domínguez Catalina , Stephan Ernst P. , Maischak Matthias
Published: August 2011

In this paper, we developed an a posteriori error analysis of a coupling of finite elements and boundary elements for a fluid–structure interaction problem in two and three dimensions. This problem is governed by the acoustic and the elastodynamic equations in time‐harmonic vibration. Our methods combined integral equations for the exterior fluid and FEMs for the elastic structure. It is well‐known that because of the reduction of the boundary value problem to boundary integral equations, the solution is not unique in general. However, because of superposition of various potentials, we consider a boundary integral equation that is uniquely solvable and avoids the irregular frequencies of the negative Laplacian operator of the interior domain. In this paper, two stable procedures were considered; one is based on the nonsymmetric formulation and the other is based on a symmetric formulation. For both formulations, we derived reliable residual a posteriori error estimates. From the estimators we computed local error indicators that allowed us to develop an adaptive mesh refinement strategy. For the two‐dimensional case we performed an adaptive algorithm on triangles, and for the three‐dimensional case we used hanging nodes on hexahedrons. Numerical experiments underline our theoretical results. Copyright © 2011 John Wiley & Sons, Ltd.
A computational procedure for prebending of wind turbine blades
Authors: Bazilevs Y. , Hsu M.‐C. , Kiendl J. , Benson D.J.
Published: August 2011

Prebending of wind turbine blades constitutes a viable engineering solution to the problem of tower clearance, that is, ensuring that during wind turbine operation there is sufficient distance between the rotor blades and the tower to avoid collision. The prebent shape of the blade must be such that when the turbine rotor is subjected to wind and inertial loads, the blades are straightened into their design configuration. In this paper, we propose a method for accurate prediction of the prebent shape of wind turbine blades. The method relies on a stand‐alone aerodynamics simulation that provides the wind loads on a rigidly spinning rotor, followed by a series of structural mechanics simulations to determine the stress‐free prebent shape of the blade. This procedure involves only one‐way coupling between the fluid and structural mechanics, which avoids the challenges of solving the coupled fluid–structure interaction problem. The proposed methodology, which has no limitations on the blade geometry and structural modeling, is successfully applied to prebending of a 63‐m offshore wind turbine blade. Copyright © 2011 John Wiley & Sons, Ltd.
Coupling of nonlocal and local continuum models by the Arlequin approach
Authors: Han Fei , Lubineau Gilles
Published: August 2011

The objective of this work is to develop and apply the Arlequin framework to couple nonlocal and local continuum mechanical models. A mechanically‐based model of nonlocal elasticity, which involves both contact and long‐range forces, is used for the ‘fine scale’ description in which nonlocal interactions are considered to have non‐negligible effects. Classical continuum mechanics only involving local contact forces is introduced for the rest of the structure where these nonlocal effects can be neglected. Both models overlap in a coupling subdomain called the ‘gluing area’ in which the total energy is separated into nonlocal and local contributions by complementary weight functions. A weak compatibility is ensured between kinematics of both models using Lagrange multipliers over the gluing area. The discrete formulation of this specific Arlequin coupling framework is derived and fully described. The validity and limits of the technique are demonstrated through two‐dimensional numerical applications and results are compared against those of the fully nonlocal elasticity method. Copyright © 2011 John Wiley & Sons, Ltd.
Diagnosis and management of early‐onset dementia
Authors: Davies R Rhys , Doran Mark , Larner Andrew J
Published: August 2011

The casemix of an early‐onset dementia clinic is different from that usually seen by old age psychiatrists or geriatricians and includes frontotemporal lobar degeneration, prion disease and genetically determined dementia as well as Alzheimer's disease. This brief review summarises the causes, diagnostic considerations and management of early‐onset dementias based on the authors' experience of working in a neurology‐led cognitive function clinic at a regional neuroscience centre. Copyright © 2011 Wiley Interface Ltd
Synthesis and characterization of new π‐conjugated polymers containing 1,8‐naphthyridine in the main chain: Role of the 1,8‐naphthyridine unit in π‐conjugated polymers
Authors: Koizumi Take‐Aki , Kato Shinichirou , Yamamoto Takakazu
Published: August 2011

Alternating π‐conjugated copolymers of 1,8‐naphthyridine‐2,6‐diyl (1,8‐Nap) with 9,9‐dioctylfluorene‐2,7‐diyl (P(Flu‐Ph‐1,8‐Nap)) and 2,5‐didodecyloxy‐1,4‐phenylene (P(ROPh‐Ph‐1,8‐Nap)) have been synthesized by Pd‐catalyzed organometallic polycondensation. The copolymers showed UV‐vis absorption peaks at around 390 nm in o‐dichlorobenzene. The polymers were photoluminescent both in o‐dichlorobenzene and in the solid state. In o‐dichlorobenzene, the emission peaks of P(Flu‐Ph‐1,8‐Nap) and P(ROPh‐Ph‐1.,8‐Nap) appeared at λEM = 440 and 471 nm, with quantum yields of 87% and 66%, respectively. Electrochemical data revealed that 1,8‐Nap behaved as a typical electron‐accepting unit. When P(Flu‐Ph‐1,8‐Nap) was treated with 10‐camphorsulfonic acid, the emission peak shifted to λEM = 598 nm. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Dual crosslinked phenylethynyl end‐capped sulfonated polyimides via the ethynyl and sulfonate groups promoted by PEG
Authors: Gong Chenliang , Luo Qiang , Li Yanfeng , Giotto Marcus , Cipollini Ned E. , Yang Zhiwei , Weiss R. A. , Scola Daniel A.
Published: August 2011

Typically, phenylethynyl (PE) end‐capped oligomides require a temperature of 370 °C for 1 h to develop a crosslinked system. A published method using poly(ethylene glycol)s (DM‐PEG‐250 and PEG‐400) as cosolvents with NMP was effective in crosslinking the ethynyl end‐caps at 250 °C/3 h in nonsulfonated oligomides. The application of this novel crosslinked method to PE end‐capped sulfonated oligomides was effective but caused a secondary crosslinked network via the sulfonic acid groups and ethylene glycol solvents. The solid‐state 13C NMR spectral data on 13C‐labeled end‐caps in the PE‐3F‐SPI‐3 oligomide provide evidence for the ethynyl to ethynyl and ethylene oxide sulfonate ester dual crosslinked structure. Infrared spectroscopy of model compounds also provides evidence for the presence of crosslinked sulfonate ester and appended sulfonate ester side chains. 13C NMR also provided quantitative data on the extent of the ethynyl to ethynyl crosslinking reaction and sulfonate ester crosslinks and side chains. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
The effect of structural variations on aromatic polyethers for high‐temperature PEM fuel cells
Authors: Morfopoulou Christina , Andreopoulou Aikaterini K. , Kallitsis Joannis K.
Published: August 2011

Three series of new aromatic polyether sulfones bearing phenyl, p‐tolyl or carboxyl side groups, respectively, and polar pyridine main chain groups were developed. Most of the polymeric materials presented high molecular weights and excellent solubility in common organic solvents. More importantly, they formed stable, self‐standing membranes that were thoroughly characterized in respect to their thermal, mechanical and oxidative stability, their phosphoric acid doping ability and ionic conductivity. Particularly, the copolymers bearing side p‐tolyl or carboxyl groups fulfill all necessary requirements for application as proton electrolyte membranes in high temperature fuel cells, which are glass transition temperatures higher than 220 °C, thermal stability up to 400 °C, oxidative stability, high doping levels (DLs) and proton conductivities of about 0.02 S/cm. Initial single fuel cell results at high temperatures, 160 °C or 180 °C, using a copolymer bearing p‐tolyl side groups with a relatively low DLs around 200 wt % and dry H2/Air feed gases, revealed efficient power generation with a current density of 0.5 A/cm2 at 500 mV. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Influence of thermal history and humidity on the ionic conductivity of nanoparticle‐filled solid polymer electrolytes
Authors: Fullerton‐Shirey Susan K. , Ganapatibhotla Lalitha V. N. R. , Shi Wenjin , Maranas Janna K.
Published: August 2011

The crystallinity and conductivity of nanoparticle‐filled solid polymer electrolytes (SPEs) are investigated as a function of thermal history and water content. Our objective is to evaluate how performance is affected by the conditions under which the SPEs are handled and tested. The samples consist of polyethylene oxide (PEO), LiClO4, and Al2O3 nanoparticles. At low humidity, SPEs at ether oxygen to lithium ratios of 8:1 do not crystallize immediately; instead, 3 days are required for crystallization to occur, and this does not depend strongly on the presence of nanoparticles. The conductivity is improved by the addition of nanoparticles at low humidity, but only at an ether oxygen to lithium ratio of 10:1, which corresponds to the eutectic concentration. At high humidity, the recrystallization time is delayed for 3 weeks, and the conductivity increases in both filled and unfilled SPEs beyond that of the low humidity samples. Although we observe that water amplifies the influence of nanoparticles on conductivity, we also find that nanoparticles inhibit water uptake—but only in the presence of lithium. Because Li+ strongly absorbs water, this result suggests that nanoparticles may interact directly with Li+ ions to prevent water uptake. In filled samples at the eutectic concentration (10:1), more water is absorbed compared to the nanoparticle‐filled 8:1 samples, even though less lithium is present. This suggests that nanoparticles may segregate to lithium‐poor regions in the 10:1 samples, and this scenario is supported by the morphology that would be expected at the eutectic concentration. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1496–1505, 2011
The dimerization interface of the glycoprotein Ibβ transmembrane domain corresponds to polar residues within a leucine zipper motif
Authors: Wei Peng , Liu Xin , Hu Miao‐Hui , Zuo Li‐Min , Kai Ming , Wang Rui , Luo Shi‐Zhong
Published: August 2011

Experiments with the transmembrane (TM) domains of the glycoprotein (GP) Ib‐IX complex have indicated that the associations between the TM domains of these subunits play an important role in the proper assembly of the complex. As a first step toward understanding these associations, we previously found that the Ibβ TM domain dimerized strongly in Escherichia coli cell membranes and led to Ibβ TM‐CYTO (cytoplasmic domain) dimerization in the SDS‐PAGE assay, while neither Ibα nor IX TM‐CYTO was able to dimerize. In this study, we used the TOXCAT assay to probe the Ibβ TM domain dimerization interface by Ala‐ and Leu‐scanning mutagenesis. Our results show that this interface is based on a leucine zipper‐like heptad repeat pattern of amino acids. Mutating either one of polar residues Gln129 or His139 to Leu or Ala disrupted Ibβ TM dimerization dramatically, indicating that polar residues might form part of the leucine zipper‐based dimerization interface. Furthermore, these specific mutational effects in the TOXCAT assay were confirmed in the thiol‐disulfide exchange and SDS‐PAGE assays. The computational modeling studies further revealed that the most likely leucine zipper interface involves hydrogen bonding of Gln129 and electrostatic interaction of the His139 side chain. Correlation of computer modeling results with experimental mutagenesis studies on the Ibβ TM domain may provide insights for understanding the role of the association of TM domains on the assembly of GP Ib‐IX complex.
Diamond ultra‐microelectrode arrays for achieving maximum Faradaic current with minimum capacitive charging
Authors: Yang Nianjun , Smirnov Waldemar , Hees Jakob , Hoffmann René , Kriele Armin , Obloh Harald , Müller‐Sebert Wolfgang , Nebel Christoph E.
Published: August 2011

All‐diamond ultra‐microelectrode arrays (UMEAs) were fabricated using standard photolithography processes. The array consists of typically 45 ultra‐microelectrodes with a diameter of 10 µm and with a center‐to‐center spacing of 60 µm. The quasi‐reference and counter electrodes are made from conductive diamond and integrated on a 5 × 5 mm2 chip. The arrays with different surface terminations were characterized using cyclic voltammetry and the redox couple of ${\rm Fe(CN)}_{{\rm 6}}^{{{{\rm 3}{-} } \mathord{\left/ {\vphantom {{{\rm 3}{-} } {4{-} }}} \right. \kern-\nulldelimiterspace} {4{-} }}} $ as probes. A peak‐shaped voltammogram was detected on electrochemically hydrogen‐terminated surface if scanned with a slow scan rate (e.g. 20 mV/s), resulting in a higher ratio of the Faradaic current (signal) to capacitive charging current (background current). A sensitive and reproducible detection of hydrogen peroxide was achieved by using the UMEA. The net‐charge for the oxidation of hydrogen peroxide at 0.4 V (vs. C) is linear with the concentration of hydrogen peroxide in the range of 6.5–650 µM. The detection limit is 2.0 µM, which is 100 times better than that obtained on the macro‐sized boron‐doped diamond electrode.
Persistent ocean monitoring with underwater gliders: Adapting sampling resolution
Authors: Smith Ryan N. , Schwager Mac , Smith Stephen L. , Jones Burton H. , Rus Daniela , Sukhatme Gaurav S.
Published: August 2011

Ocean processes are dynamic and complex and occur on multiple spatial and temporal scales. To obtain a synoptic view of such processes, ocean scientists collect data over long time periods. Historically, measurements were continually provided by fixed sensors, e.g., moorings, or gathered from ships. Recently, an increase in the utilization of autonomous underwater vehicles has enabled a more dynamic data acquisition approach. However, we still do not utilize the full capabilities of these vehicles. Here we present algorithms that produce persistent monitoring missions for underwater vehicles by balancing path following accuracy and sampling resolution for a given region of interest, which addresses a pressing need among ocean scientists to efficiently and effectively collect high‐value data. More specifically, this paper proposes a path planning algorithm and a speed control algorithm for underwater gliders, which together give informative trajectories for the glider to persistently monitor a patch of ocean. We optimize a cost function that blends two competing factors: maximize the information value along the path while minimizing deviation from the planned path due to ocean currents. Speed is controlled along the planned path by adjusting the pitch angle of the underwater glider, so that higher resolution samples are collected in areas of higher information value. The resulting paths are closed circuits that can be repeatedly traversed to collect long‐term ocean data in dynamic environments. The algorithms were tested during sea trials on an underwater glider operating off the coast of southern California, as well as in Monterey Bay, California. The experimental results show improvements in both data resolution and path reliability compared to previously executed sampling paths used in the respective regions. © 2011 Wiley Periodicals, Inc.
Performance evaluation of 1‐point‐RANSAC visual odometry
Authors: Scaramuzza Davide
Published: August 2011

Monocular visual odometry is the process of computing the egomotion of a vehicle purely from images of a single camera. This process involves extracting salient points from consecutive image pairs, matching them, and computing the motion using standard algorithms. This paper analyzes one of the most important steps toward accurate motion computation, which is outlier removal. The random sample consensus (RANSAC) has been established as the standard method for model estimation in the presence of outliers. RANSAC is an iterative method, and the number of iterations necessary to find a correct solution is exponential in the minimum number of data points needed to estimate the model. It is therefore of utmost importance to find the minimal parameterization of the model to estimate. For unconstrained motion [six degrees of freedom (DoF)] of a calibrated camera, this would be five correspondences. In the case of planar motion, the motion model complexity is reduced (three DoF) and can be parameterized with two points. In this paper we show that when the camera is installed on a nonholonomic wheeled vehicle, the model complexity reduces to two DoF and therefore the motion can be parameterized with a single‐point correspondence. Using a single‐feature correspondence for motion estimation is the lowest model parameterization possible and results in the most efficient algorithm for removing outliers, which we call 1‐point RANSAC. To support our method, we run many experiments on both synthetic and real data and compare the performance with state‐of‐the‐art approaches and with different vehicles, both indoors and outdoors. © 2011 Wiley Periodicals, Inc.
USING ECOLOGICAL AND BIOGEOGRAPHICAL FEATURES TO PRODUCE A TYPOLOGY OF THE PLANT SPECIES USED IN BIOENGINEERING FOR RIVERBANK PROTECTION IN EUROPE
Authors: Evette A. , Balique C. , Lavaine C. , Rey F. , Prunier P.
Published: August 2011

River managers involved in riverbank protection need plant‐selection guidelines based on the biogeographical and ecological requirements of a wide variety of plant species. In this study, we propose a double typology of the woody plant species used in riverbank protection bioengineering in Europe based on ecological and biogeographical features.

The statistical analyses of existing data highlight the important role played by waterlogging tolerance, soil moisture, soil productivity and light exposure in species classification, whereas acidity was less selective. Ninety‐five species were classified in 11 ecological groups according to the six ecological variables. Based on three biogeographical variables (altitude, continentality and geographic distribution), a second classification gave five biogeographical groups clustering species according to their geographic preferences.

Independent biogeographical and ecological typologies allow river managers to be consistent with the regional altitudinal and climatic environment and to select species adapted to the local environmental conditions of the riverbank considered. This study is of particular interest because its methodology and results are applicable to slope protection in general as well as to potential changes resulting from climate change. Copyright © 2011 John Wiley & Sons, Ltd.
The use of subgrains as imaged in the SEM from bulk specimens in the study of localized plasticity
Authors: Davidson D. L.
Published: August 2011

The ability to image subgrains in the SEM by channeling contrast affords the opportunity to study localized plasticity and quantify parameters not previously measurable. This paper examines some of the ways in which subgrain information may be used in the study of fatigue and creep phenomena. Fatigue crack tip stress range and the work required to form a fatigue crack may be estimated. An example of the measurement of subgrain misorientation due to creep is also given.
Measurements of electron channeling pattern linewidths in silicon
Authors: Farrow R. C. , Joy D. C.
Published: August 2011

Using a new method for improving the signal‐to‐noise of electron channeling pattern (ECP) contrast, preliminary quantitative measurements of the linewidths of ECP lines in silicon have been performed. The signal‐to‐noise was improved by utilizing a boxcar integrating circuit whose gating logic was referenced to the SEM horizontal scan signal. The measurements were done on the (220) series of reflections from 18 and 25 keV incident electrons by monitoring the specimen current as the SEM was scanning in the line mode. The measured linewidths are consistent with those predicted by the two beam theory of ECP intensity when the affects of the incident beam divergence, α, are accounted for. The appearance of ECP lines from very high order reflections is an indication that the limit of the reciprocal lattice vector, g, of a line that can be resolved in an ECP is limited more by the sample than by α. The finite α appears only to broaden the linewidths of higher order lines. These studies are being pursued to explore the potential of this technique for the study of crystalline perfection.
Scanning electron microscopy of two‐dimensional magnetic stray fields
Authors: Rau E. I. , Spivak G. V.
Published: August 2011

Methods used in metrology of two‐dimensional magnetic microfields and based on direct interaction of the electron beam of scanning electron microscope (SEM) with the studied fields are described. An analytical expression for calculating the value of the field is presented. The errors and applicability of the methods have been estimated. The concepts discussed are illustrated by the experimental results of the measurements of some types of statistical and dynamic stray fields.
Methods for quantitative analysis in secondary ion mass spectrometry
Authors: Newbury Dale E.
Published: August 2011

Methods for quantitative analysis in secondary ion mass spectrometry must be capable of correcting for strong matrix effects on emitted secondary ion intensities as well as strong instrumental effects on measured secondary ion intensities. Both empirical methods, based on sensitivity factors and working curves, and theoretical models for secondary ion emission, are available. Absolute sensitivity factors are not satisfactory because of the lack of compensation for matrix effects. Working curves are capable of yielding analysis with 5% relative accuracy but offer poor flexibility in dealing with unknowns which differ strongly from the standards. Relative sensitivity factors offer both flexibility in the analysis of unknowns and an error distribution in which 80% of the analyses fall within a factor of 2 of the unknown and 99% within a factor of 5. Numerous physical models for secondary ion emission are available but are generally limited in application due to uncertainties in the required physical data. The local thermal equilibrium (LTE) model is broadly applicable with partial constraint on the composition of the unknown. The LTE error distribution places about 50% of the analyses within a factor of 2 and 80% within a factor of 5. Large errors, exceeding a factor of 10, are observed for heavy elements, possibly due to uncorrected instrument effects.

Future development of analytical methods may combine the relative sensitivity factor method (which minimizes the influence of instrument artifacts) with the theoretical description of secondary ion emission (to calculate matrix effects).
Morphological polarity in oral epithelial cells revealed by boric acid partial dissociation
Authors: Newcomb G. M.
Published: August 2011

Layers of epithelium were stripped with adhesive tape from the surface of rat palatal mucosa after that tissue had been fixed in OsO4, treated in 0.2 M boric acid and critical point or freeze dried. Cell layers stripped off evenly with very few intracellular fractures. The oral surface of cells in the stratum corneum was characterized by small pits and raised cell boundaries. By contrast the deep aspect of these cells displayed microvilli and linear grooves which exactly matched the pits and raised boundaries on the opposing cell beneath. Partial dissociation with boric acid after OsO4 fixation greatly assists the demonstration of complementary cell surfaces deep in the epithelium.
A method for preparing colored scanning electron micrographs using SE and BSE images
Authors: Tanaka K.
Published: August 2011

Biological specimens impregnated with heavy metal are observed in an SEM equipped with a sensitive BSE detector. The SE image and the BSE image are successively recorded under the same conditions. Both pictures are displayed coincidentally on a screen, using two projectors of the same type, but with different color filters. The resulting color picture is photographed with color film. Specific regions of the specimen which were impregnated with heavy metal are clearly demonstrated.