bluuebunny/crossref_metadata_2025 huggingface dataset:
What controls the local time extent of flux transfer events?
Authors: Milan S. E. , Imber S. M. , Carter J. A. , Walach M.‐T. , Hubert B.
Published: February 2016

Flux transfer events (FTEs) are the manifestation of bursty and/or patchy magnetic reconnection at the magnetopause. We compare two sequences of the ionospheric signatures of flux transfer events observed in global auroral imagery and coherent ionospheric radar measurements. Both sequences were observed during very similar seasonal and interplanetary magnetic field (IMF) conditions, though with differing solar wind speed. A key observation is that the signatures differed considerably in their local time extent. The two periods are 26 August 1998, when the IMF had components BZ≈−10 nT and BY≈9 nT and the solar wind speed was VX≈650 km s−1, and 31 August 2005, IMF BZ≈−7 nT, BY≈17 nT, and VX≈380 km s−1. In the first case, the reconnection rate was estimated to be near 160 kV, and the FTE signatures extended across at least 7 h of magnetic local time (MLT) of the dayside polar cap boundary. In the second, a reconnection rate close to 80 kV was estimated, and the FTEs had a MLT extent of roughly 2 h. We discuss the ramifications of these differences for solar wind‐magnetosphere coupling.
Empirical model of the Martian dayside ionosphere: Effects of crustal magnetic fields and solar ionizing flux at higher altitudes
Authors: Němec F. , Morgan D. D. , Gurnett D. A. , Andrews D. J.
Published: February 2016

We use electron density profiles measured by the Mars Advanced Radar for Subsurface and Ionosphere Sounding instrument on board the Mars Express spacecraft to investigate the effects of possible controlling parameters unconsidered in the empirical model of Němec et al. (2011, hereafter N11). Specifically, we focus on the effects of crustal magnetic fields and F10.7 proxy of the solar ionizing flux at higher altitudes. It is shown that while peak electron densities are nearly unaffected by crustal magnetic fields, electron densities at higher altitudes are significantly increased in areas of stronger magnetic fields. The magnetic field inclination appears to have only a marginal effect. Moreover, while the N11 empirical model accounted for the variable solar ionizing flux at low altitudes, the high‐altitude diffusive region was parameterized only by the solar zenith angle and the altitude. It is shown that this can lead to considerable inaccuracies. A simple correction of the N11 model, which takes into account both the crustal magnetic field magnitude and the effect of F10.7 at higher altitudes, is suggested.
Simulating runoff under changing climatic conditions: Revisiting an apparent deficiency of conceptual rainfall‐runoff models
Authors: Fowler Keirnan J. A. , Peel Murray C. , Western Andrew W. , Zhang Lu , Peterson Tim J.
Published: February 2016

Hydrologic models have potential to be useful tools in planning for future climate variability. However, recent literature suggests that the current generation of conceptual rainfall runoff models tend to underestimate the sensitivity of runoff to a given change in rainfall, leading to poor performance when evaluated over multiyear droughts. This research revisited this conclusion, investigating whether the observed poor performance could be due to insufficient model calibration and evaluation techniques. We applied an approach based on Pareto optimality to explore trade‐offs between model performance in different climatic conditions. Five conceptual rainfall runoff model structures were tested in 86 catchments in Australia, for a total of 430 Pareto analyses. The Pareto results were then compared with results from a commonly used model calibration and evaluation method, the Differential Split Sample Test. We found that the latter often missed potentially promising parameter sets within a given model structure, giving a false negative impression of the capabilities of the model. This suggests that models may be more capable under changing climatic conditions than previously thought. Of the 282[347] cases of apparent model failure under the split sample test using the lower [higher] of two model performance criteria trialed, 155[120] were false negatives. We discuss potential causes of remaining model failures, including the role of data errors. Although the Pareto approach proved useful, our aim was not to suggest an alternative calibration strategy, but to critically assess existing methods of model calibration and evaluation. We recommend caution when interpreting split sample results.
Testing the hybrid‐3‐D hillslope hydrological model in a controlled environment
Authors: Hazenberg P. , Broxton P. , Gochis D. , Niu G.‐Y. , Pangle L. A. , Pelletier J. D. , Troch P. A. , Zeng X.
Published: February 2016

Hillslopes are important for converting rainfall into runoff, influencing the terrestrial dynamics of the Earth's climate system. Recently, we developed a hybrid‐3‐D (h3D) hillslope hydrological model that gives similar results as a full 3‐D hydrological model but is up to 2–3 orders of magnitude faster computationally. Here h3D is assessed using a number of recharge‐drainage experiments within the Landscape Evolution Observatory (LEO) with accurate and high‐resolution (both temporally and spatially) observations of the inputs, outputs, and storage dynamics of several hillslopes. Such detailed measurements are generally not available for real‐world hillslopes. Results show that the h3D model captures the observed storage, base flow, and overland flow dynamics of both the larger LEO and the smaller miniLEO hillslopes very well. Sensitivity tests are also performed to understand h3Ds difficulty in representing the height of the saturated zone close to the seepage face of the miniLEO hillslope. Results reveal that a temporally constant parameters set is able to simulate the response of the miniLEO for each individual event. However, when one focuses on the saturated zone dynamics at 0.15 m from the seepage face, a stepwise evolution of the optimal model parameter for the saturated lateral conductivity parameter of the gravel layer occurs. This evolution might be related to the migration of soil particles within the hillslope. However, it is currently unclear whether and where this takes place (in the seepage face or within the parts of the loamy sand soil).
Dealloyed AuNi Dendrite Anchored on a Functionalized Conducting Polymer for Improved Catalytic Oxygen Reduction and Hydrogen Peroxide Sensing in Living Cells
Authors: Naveen Malenahalli Halappa , Gurudatt Nanjanagudu Ganesh , Noh Hui‐Bog , Shim Yoon‐Bo
Published: February 2016

Dealloyed‐AuNi dendrite anchored on carboxylic acid groups of a conducting polymer is prepared and demonstrated for the catalysis of the oxygen reduction reaction (ORR) and detection of hydrogen peroxide (H2O2) released from living cells. The dendrite formation is initiated on a poly(benzoic acid‐2,2′:5′,2′′‐terthiophene) (pTBA) layer, where the polymer layer acts as a stable substrate to improve the long‐term stability and catalytic activity of the alloy electrode. A co‐deposition of Au and Ni is performed to produce a Ni‐rich Au surface at first; subsequent removal of the surface Ni atoms through electrochemical dealloying enhances the performance of the catalyst because of an increase in the electrochemically active area by 12 times. The hydrodynamic voltammetry of dealloyed‐AuNi@pTBA shows a half‐wave potential at –0.08 V, which is a large shift towards more positive potential when compared to those on AuNi@pTBA (−0.14 V) and commercial Pt/C (–0.12 V) electrodes. The proposed catalytic electrode achieved a superior analytical performance for the detection of trace H2O2 (at –0.15 V) released from cancer and normal cells with a very low detection limit (ca. 5 nM). In addition, the in vitro studies suggest no significant cytotoxicity effect for the dealloyed sample and the viability of the cells are more than 85% even after 48 h of incubation.
Effects of Graphene Quantum Dots on the Self‐Renewal and Differentiation of Mesenchymal Stem Cells
Authors: Qiu Jichuan , Li Deshuai , Mou Xiaoning , Li Jianhua , Guo Weibo , Wang Shu , Yu Xin , Ma Baojin , Zhang Shan , Tang Wei , Sang Yuanhua , Gil Pilar Rivera , Liu Hong
Published: February 2016

The influence of graphene quantum dots (GQDs) on key characteristics of bone marrow derived mesenchymal stem cells (MSCs) phenotype (i.e., self‐renewal, differentiation potential, and pluripotency) is systematically investigated in this work. First, the viability and impact of GQDs on the self‐renewal potential of MSCs is evaluated in order to determine a threshold for the exposing dose. Second, GQDs uptake by MSCs is confirmed due to the excellent fluorescent properties of the particles. They exhibit a homogenous cytoplasmatic distribution that increases with the time and concentration. Third, the impact of GQDs on the osteogenic differentiation of MSCs is deeply characterized. An enhanced activity of alkaline phosphatase promoted by GQDs indicates early activation of osteogenesis. This is also confirmed upon GQD‐induced up‐regulation of phenotypically related osteogenic genes (Runx2, osteopontin, and osteocalcin) and specific biomarkers expression (osteopontin and osteocalcin). GQDs also effectively enhance the formation of calcium‐rich deposits characteristics of osteoblasts. Furthermore, genes microarray results indicate that the enhanced osteogenic differentiation of MSCs by GQDs is in progress through a bone morphogenetic protein and transforming growth factor‐β relative signaling pathways. Finally, intracytoplasmatic lipid detection shows that GQDs can also promote the adipogenic differentiation of MSCs, thus confirming the prevalence of their pluripotency potential.
New‐Generation Graphene from Electrochemical Approaches: Production and Applications
Authors: Yang Sheng , Lohe Martin R. , Müllen Klaus , Feng Xinliang
Published: February 2016

Extensive research suggests a bright future for the graphene market. However, for a long time there has been a huge gap between laboratory‐scale research and commercial application due to the challenging task of reproducible bulk production of high‐quality graphene at low cost. Electrochemical exfoliation of graphite has emerged as a promising wet chemical method with advantages such as upscalability, solution processability and eco‐friendliness. Recent progress in the electrochemical exfoliation of graphite and prospects for the application of exfoliated graphene, mainly in the fields of composites, electronics, energy storage and conversion are discussed.
Thermoelectric Polymers and their Elastic Aerogels
Authors: Khan Zia Ullah , Edberg Jesper , Hamedi Mahiar Max , Gabrielsson Roger , Granberg Hjalmar , Wågberg Lars , Engquist Isak , Berggren Magnus , Crispin Xavier
Published: February 2016

Electronically conducting polymers constitute an emerging class of materials for novel electronics, such as printed electronics and flexible electronics. Their properties have been further diversified to introduce elasticity, which has opened new possibility for “stretchable” electronics. Recent discoveries demonstrate that conducting polymers have thermoelectric properties with a low thermal conductivity, as well as tunable Seebeck coefficients – which is achieved by modulating their electrical conductivity via simple redox reactions. Using these thermoelectric properties, all‐organic flexible thermoelectric devices, such as temperature sensors, heat flux sensors, and thermoelectric generators, are being developed. In this article we discuss the combination of the two emerging fields: stretchable electronics and polymer thermoelectrics. The combination of elastic and thermoelectric properties seems to be unique for conducting polymers, and difficult to achieve with inorganic thermoelectric materials. We introduce the basic concepts, and state of the art knowledge, about the thermoelectric properties of conducting polymers, and illustrate the use of elastic thermoelectric conducting polymer aerogels that could be employed as temperature and pressure sensors in an electronic‐skin.
Reversing Adhesion: A Triggered Release Self‐Reporting Adhesive
Authors: Schenzel Alexander M. , Klein Christopher , Rist Kai , Moszner Norbert , Barner‐Kowollik Christopher
Published: February 2016

Here, the development of an adhesive is reported – generated via free radical polymerization – which can be degraded upon thermal impact within minutes. The degradation is based on a stimuli responsive moiety (SRM) that is incorporated into the network. The selected SRM is a hetero Diels‐Alder (HDA) moiety that features three key properties. First, the adhesive can be degraded at relatively low temperatures (≈80 °C), second the degradation occurs very rapidly (less than 3 min), and third, the degradation of the network can readily be analyzed and quantified due to its self‐reporting nature. The new reversible self‐reporting adhesion system is characterized in detail starting from molecular studies of the retro HDA reaction. Moreover, the mechanical properties of the network, as well as the adhesion forces, are investigated in detail and compared to common methacrylate‐based systems, demonstrating a significant decrease in mechanic stability at elevated temperatures. The current study thus represents a significant advance of the current state of the art for debonding on demand adhesives, making the system interesting for several fields of application including dental adhesives.
The Morphological Power of Soap: How Surfactants Lower the Sheet Resistance of PEDOT:PSS by Strong Impact on Inner Film Structure and Molecular Interface Orientation
Authors: Palumbiny Claudia M. , Schlipf Johannes , Hexemer Alexander , Wang Cheng , Müller‐Buschbaum Peter
Published: February 2016

In the rapid development of organic electronics, there is a strong need for highly conductive and transparent electrode (TE) materials to act as charge transport layers. In this context, poly(3,4‐ethylenedioxythiophene): polystyrenesulfonate (PEDOT:PSS) is a highly promising candidate, because it can act directly as TE. This makes the use of brittle, rare, and expensive indium tin oxide electrodes dispensable. Modification of the inner film morphology, e.g., by solvent additives can dramatically reduce the sheet resistance of PEDOT:PSS. In this work, it is investigated how the (fluoro)surfactant Zonyl and the co‐solvent ethylene glycol influence the electrical and optical properties of the film, namely, the sheet resistance, the transmission, and the figure of merit for TEs. The electronic characteristics are then related to the morphological changes investigated with grazing incidence small angle X‐ray scattering (GISAXS) and polarized resonant soft X‐ray scattering (P‐SoXS). Using GISAXS, structure evolutions are related to sheet resistances and device characteristics in organic solar cells. Further, the influence of (fluoro)surfactant on the phase separation and relative molecular orientation at polymer interfaces is investigated utilizing P‐SoXS. Transparent PEDOT:PSS films with low sheet resistance are essential for market introduction and mark the next milestone for the success of future organic electronic materials.
Low‐Temperature‐Processed 9% Colloidal Quantum Dot Photovoltaic Devices through Interfacial Management of p–n Heterojunction
Authors: Azmi Randi , Aqoma Havid , Hadmojo Wisnu Tantyo , Yun Jin‐Mun , Yoon Soyeon , Kim Kyungkon , Do Young Rag , Oh Seung‐Hwan , Jang Sung‐Yeon
Published: February 2016

Low‐temperature solution‐processed high‐efficiency colloidal quantum dot (CQD) photovoltaic devices are developed by improving the interfacial properties of p–n heterojunctions. A unique conjugated polyelectrolyte, WPF‐6‐oxy‐F, is used as an interface modification layer for ZnO/PbS‐CQD heterojunctions. With the insertion of this interlayer, the device performance is dramatically improved. The origins of this improvement are determined and it is found that the multifunctionality of the WPF‐6‐oxy‐F interlayer offers the following essential benefits for the improved CQD/ZnO junctions: (i) the dipole induced by the ionic substituents enhances the quasi‐Fermi level separation at the heterojunction through favorable energy band‐bending, (ii) the ethylene oxide groups containing side chains can effectively passivate the interfacial defect sites of the heterojunction, and (iii) these effects occur without deterioration in the intrinsic depletion region or the series resistance of the device. All of the figures‐of‐merit of the devices are improved as a result of the enhanced built‐in potential (electric field) and the reduced interfacial charge recombination at the heterojunction. The benefits due to the WPF‐6‐oxy‐F interlayer are generally applicable to various types of PbS/ZnO heterojunctions. Finally, CQD photovoltaic devices with a power conversion efficiency of 9% are achievable, even by a solution process at room temperature in an air atmosphere. The work suggests a useful strategy to improve the interfacial properties of p–n heterojunctions by using polymeric interlayers.
Interfacial tensions of industrial fluids from a molecular‐based square gradient theory
Authors: Garrido José Matías , Mejía Andrés , Piñeiro Manuel M. , Blas Felipe J. , Müller Erich A.
Published: February 2016

This work reports a procedure for predicting the interfacial tension (IFT) of pure fluids. It is based on scaling arguments applied to the influence parameter of the van der Waals theory of inhomogeneous fluids. The molecular model stems from the application of the square gradient theory to the SAFT‐VR Mie equation of state. The theory is validated against computer simulation results for homonuclear pearl‐necklace linear chains made up to six Mie (λ − 6) beads with repulsive exponents spanning from λ = 8 to 44 by combining the theory with a corresponding states correlation to determine the intermolecular potential parameters. We provide a predictive tool to determine IFTs for a wide range of molecules including hydrocarbons, fluorocarbons, polar molecules, among others. The proposed methodology is tested against comparable existing correlations in the literature, proving to be vastly superior, exhibiting an average absolute deviation of 2.2%. © 2016 American Institute of Chemical EngineersAIChE J, 62: 1781–1794, 2016
Extended HPM–DEM coupled simulation of drainage of square particles in a 2D hopper flow
Authors: Gui Nan , Yang Xingtuan , Jiang Shengyao , Tu Jiyuan , Fan Jianren
Published: February 2016

An extended hard particle method–discrete element method coupled model (EHPM–DEM) is proposed to simulate the drainage of square particle in 2D hoppers. The EHPM extends the hard sphere model to adapt for non‐spherical shapes. A vertex‐based extension of DEM is developed to solve collisions of square particles. A new coupled method is proposed, using the EHPM to simulate binary collisions and DEM to simulate multiple contacts. The collision between two triangles and the drainage of square particles in hoppers were simulated and compared to theoretical analysis and experiments, respectively, for validation. Moreover, the advantages of EHPM over DEM and the EHPM–DEM coupled solution over the pure soft DEM solution in computational efficiency have been demonstrated. In addition, the effects of restitution coefficient, friction coefficient, and the filled height on the discharge rates are analyzed, and a uniform discharge feature is discovered, which is especially useful for scaling studies. © 2016 American Institute of Chemical Engineers AIChE J, 62: 1863–1876, 2016
Pd‐Catalyzed Late‐Stage Monoacetoxylation and Monoiodination of 4‐Alkyl‐1,5‐diaryl‐1 H‐pyrazole‐3‐carboxylates via Direct Csp2−H Bond Activation
Authors: Fan Xue‐Min , Guo Ying , Li Yu‐Dan , Yu Kun‐Kun , Liu Hong‐Wei , Liao Dao‐Hua , Ji Ya‐Fei
Published: February 2016

A palladium‐catalyzed, late‐stage functionalization of 4‐alkyl‐1,5‐diaryl‐1 H‐pyrazole‐3‐carboxylates to achieve acetoxylation or iodination via Csp2−H bond activation with synthetically useful to excellent yields is described. These straightforward transformations feature highly functionalized substrates, excellent site selectivity, rapid reaction, and simple operation. The C−O and C−I bond‐forming protocols allow convenient accesses to lots of complex monoacetoxylated and monoiodinated products from pharmaceutically important intermediates. Iodoacetic acid is also used as the iodinating agent in C−H bond activation.
Effectiveness of leukotriene receptor antagonism in the postoperative management of chronic rhinosinusitis
Authors: Yelverton Joshua C. , Holmes Thomas W. , Johnson Christopher M. , Gelves Camilo Reyes , Kountakis Stilianos E.
Published: February 2016

Background

Montelukast is used in the treatment of allergic rhinitis and asthma. It has been used as adjuvant therapy in patients with chronic rhinosinusitis (CRS), but its effectiveness has not been evaluated. This study evaluates the efficacy of adjuvant leukotriene receptor antagonism in CRS and subtypes.

Methods

Retrospective review of collected data at a tertiary‐referral institution. We identified all patients who were prescribed montelukast postoperatively and had a lapse in therapy for at least 1 month (n = 50), so that the patients themselves serve as their own control group. Twenty‐item Sino‐Nasal Outcomes Test (SNOT‐20) scores and Lund‐Kennedy endoscopy scores were obtained for each patient. Scores were compared with and without montelukast using Wilcoxon signed rank test. The analysis was controlled for changes in other medications.

Results

Fifty‐two therapy lapses were identified in 50 patients. Twenty‐seven patients had eosinophilic CRS with polyps (eCRSwNP), 8 had Samter's triad (ST), and 15 had allergic fungal sinusitis (AFS). Overall mean follow‐up was 46.5 months. Overall, SNOT‐20 scores and endoscopy scores were significantly lower with montelukast (p < 0.005 for both). On subgroup analysis, SNOT‐20 scores were significantly improved for patients with eCRSwNP and AFS (p < 0.001 and p = 0.001, respectively). Endoscopy scores were significantly improved for patients with eCRSwNP (p = 0.044). Outcomes approached, but did not reach, significance for patients with ST (p = 0.123 for SNOT‐20 and p = 0.146 for endoscopy). There was also significant improvements in patients with asthma.

Conclusion

The addition of montelukast as postoperative therapy may be beneficial for patients with eCRSwNP and AFS.
Total and allergen‐specific immunoglobulin E in the serum and nasal mucosa of a nonallergic population
Authors: Reisacher William R.
Published: February 2016

Background

There has been a growing interest in measuring allergen‐specific immunoglobulin E (sIgE) directly from the nasal mucosal epithelium of individuals with sinonasal disease. However, there is currently no normative data with which to estimate sensitivity, specificity, and the appropriate positive cutoff level for new testing methods.

Methods

Twenty individuals with no history of sinonasal disease or food allergies underwent serum IgE testing and nasal mucosal brush biopsy (MBB) testing for total and sIgE to 7 common airborne allergens and 1 food allergen. The correlation between sIgE in serum and nasal samples was determined at both the 0.10‐kU/L and 0.35‐kU/L positive cutoff levels.

Results

sIgE at the 0.35‐kU/L cutoff level was detected for at least 1 allergen in 7 of 20 (35%) participants in both the serum and nose. At the 0.10‐kU/L cutoff level, 8 of 20 (40%) and 19 of 20 (95%) participants had sIgE to at least 1 allergen in the serum and nose, respectively. At the 0.35‐kU/L cutoff level, total serum IgE levels were significantly higher when at least 1 allergen was detected in the nose (p = 0.01). There was a strong association between sIgE in the serum and nasal mucosa (p < 0.0001) at both cutoff levels.

Conclusion

The significant association between serum and nasal samples for both total and sIgE suggests that nasal IgE and serum IgE are not independent of one another. Understanding levels of IgE in the nonallergic population will help answer the questions surrounding sensitization as new diagnostic tests for locally‐present IgE become available.
FINRA Dispute Resolution Task Force Releases Its Final Report, with Support for Mediation and Live Hearings
Authors: Gross Jill I.
Published: February 2016

Late in 2015, the FINRA Dispute Resolution Task Force, a group formed solely for the purpose of systematically assessing and critiquing securities arbitration, released its Final Report and Recommendations (available at bit.ly/1NTh18N.
Clinicopathological features in anterior visual pathway in neuromyelitis optica
Authors: Hokari Mariko , Yokoseki Akiko , Arakawa Musashi , Saji Etsuji , Yanagawa Kaori , Yanagimura Fumihiro , Toyoshima Yasuko , Okamoto Kouichirou , Ueki Satoshi , Hatase Tetsuhisa , Ohashi Riuko , Fukuchi Takeo , Akazawa Kohei , Yamada Mitsunori , Kakita Akiyoshi , Takahashi Hitoshi , Nishizawa Masatoyo , Kawachi Izumi
Published: February 2016

Objective

Neuromyelitis optica spectrum disorder (NMOsd) is an autoimmune disorder of the central nervous system characterized by aquaporin‐4 (AQP4) autoantibodies. The aim of this study was to elucidate the characteristics of involvement of the anterior visual pathway (AVP) and neurodegeneration via glia–neuron interaction in NMOsd.

Methods

Thirty Japanese patients with serologically verified NMOsd were assessed with a neuro‐ophthalmological study. Using 27 tissue blocks from 13 other cases of NMOsd, we performed neuropathological analysis of glial and neuroaxonal involvement in the AVP.

Results

The AVP involvement in NMOsd was characterized by the following, compared to multiple sclerosis: (1) longitudinally extensive optic neuritis (ON); (2) more severe visual impairment and worse prognosis for ON; (3) unique AQP4 dynamics, including loss of AQP4 immunoreactivity on astrocytes with complement activation in ON lesions, loss of AQP4 immunoreactivity on Müller cells with no deposition of complement in the retinas, and densely packed AQP4 immunoreactivity on astrocytes in gliosis of secondary anterograde/retrograde degeneration in the optic nerves and retinal nerve fiber layer (RNFL); and (4) more severe neurodegeneration, including axonal accumulation of degenerative mitochondria and transient receptor potential melastatin 4 channel with complement‐dependent astrocyte pathology in ON lesions, mild loss of horizontal cells, and RNFL thinning and loss of ganglion cells with abundance of AQP4+ astrocytes, indicating secondary retrograde degeneration after ON.

Interpretation

Severe and widespread neuroaxonal damage and unique dynamics of astrocytes/Müller cells with alterations of AQP4 were prominent in the AVP and may be associated with poor visual function and prognosis in NMOsd. Ann Neurol 2016;79:605–624
Transcranial Doppler versus transthoracic echocardiography for the detection of patent foramen ovale in patients with cryptogenic cerebral ischemia: A systematic review and diagnostic test accuracy meta‐analysis
Authors: Katsanos Aristeidis H. , Psaltopoulou Theodora , Sergentanis Theodoros N. , Frogoudaki Alexandra , Vrettou Agathi‐Rosa , Ikonomidis Ignatios , Paraskevaidis Ioannis , Parissis John , Bogiatzi Chrysa , Zompola Christina , Ellul John , Triantafyllou Nikolaos , Voumvourakis Konstantinos , Kyritsis Athanassios P. , Giannopoulos Sotirios , Alexandrov Anne W. , Alexandrov Andrei V. , Tsivgoulis Georgios
Published: February 2016

Objective

Patent foramen ovale (PFO) can be detected in up to 43% of patients with cryptogenic cerebral ischemia undergoing investigation with transesophageal echocardiography (TEE). The diagnostic value of transthoracic echocardiography (TTE) in the detection of PFO in patients with cryptogenic ischemic stroke or transient ischemic attack has not been compared with that of transcranial Doppler (TCD) using a comprehensive meta‐analytical approach.

Methods

We performed a systematic literature review to identify all prospective observational studies of patients with cryptogenic cerebral ischemia that provided both sensitivity and specificity measures of TTE, TCD, or both compared to the gold standard of TEE.

Results

Our literature search identified 35 eligible studies including 3,067 patients. The pooled sensitivity and specificity for TCD was 96.1% (95% confidence interval [CI] = 93.0–97.8%) and 92.4% (95% CI = 85.5–96.1%), whereas the respective measures for TTE were 45.1% (95% CI = 30.8–60.3%) and 99.6% (95% CI = 96.5–99.9%). TTE was superior in terms of higher positive likelihood ratio values (LR+ = 106.61, 95% CI = 15.09–753.30 for TTE vs LR+ = 12.62, 95% CI = 6.52–24.43 for TCD; p = 0.043), whereas TCD demonstrated lower negative likelihood values (LR− = 0.04, 95% CI = 0.02–0.08) compared to TTE (LR− = 0.55, 95% CI = 0.42–0.72; p < 0.001). Finally, the area under the summary receiver operating curve (AUC) was significantly greater (p < 0.001) in TCD (AUC = 0.98, 95% CI = 0.97–0.99) compared to TTE studies (AUC = 0.86, 95% CI = 0.82–0.89).

Interpretation

TCD is more sensitive but less specific compared to TTE for the detection of PFO in patients with cryptogenic cerebral ischemia. The overall diagnostic yield of TCD appears to outweigh that of TTE. Ann Neurol 2016;79:625–635
Synthetisch gewonnene Naturstofffragmente in der Wirkstoffentwicklung
Authors: Crane Erika A. , Gademann Karl
Published: February 2016

Die organische Chemie mit ihrer einzigartigen Fähigkeit zur maßgeschneiderten Herstellung von Naturstoff‐Analoga ist ein ausgezeichnetes Mittel, um das volle Potenzial von Naturstoffen bei der Wirkstoffentwicklung auszuschöpfen. In diesem Aufsatz stellen wir eine Strategie vor, die auf von Naturstoffen abgeleiteten Fragmenten basiert, die sich durch eine substanzielle Verringerung des Molekulargewichts, reduzierte strukturelle Komplexität und kürzere Synthesesequenzen zu ihrer Herstellung auszeichnen, während ihre für die Anwendung entscheidenden Eigenschaften wie biochemische Potenz und Selektivität beibehalten oder sogar verstärkt werden. Dies wird anhand von Beispielen aus verschiedenen Stadien des Arzneistoffentwicklungsprozesses bis hin zur klinischen Anwendung erläutert. Darüber hinaus kann die hier beschriebene Strategie durch neuartige Techniken wie die Entwicklung von Antikörper‐Wirkstoff‐Konjugaten oder Genome Mining unterstützt werden. Das Zusammenspiel dieser Ansätze birgt das Potenzial zur Entwicklung der nächsten Generation naturstoffinspirierter Wirkstoffmoleküle.
Thiophene‐S,S‐dioxidized Indophenine: A Quinoid‐Type Building Block with High Electron Affinity for Constructing n‐Type Polymer Semiconductors with Narrow Band Gaps
Authors: Deng Yunfeng , Sun Bin , He Yinghui , Quinn Jesse , Guo Chang , Li Yuning
Published: February 2016

Three thiophene‐S,S‐dioxidized indophenine (IDTO) isomers, 3 a (E,E,E), 3 b (Z,E,E), and 3 c (Z,E,Z), were synthesized by oxidation of an indophenine compound. 3 b and 3 c could be converted into the most‐stable 3 a by heating at 110 °C. An IDTO‐containing conjugated polymer, PIDTOTT, was prepared using 3 a as a comonomer through a Stille coupling reaction, and it possesses a narrow band gap and low energy levels. In organic field effect transistors (OFETs), PIDTOTT exhibited unipolar n‐type semiconductor characteristics with unexpectedly high electron mobility (up to 0.14 cm2 V−1 s−1), despite its rather disordered chain packing.
Monolayer Filaments versus Multilayer Stacking of Bent‐Core Molecules
Authors: Matraszek Joanna , Topnani Neha , Vaupotič Natasa , Takezoe Hideo , Mieczkowski Jozef , Pociecha Damian , Gorecka Ewa
Published: February 2016

Bent‐core materials exhibiting lamellar crystals (B4 phase), when dissolved in organic solvents, formed gels with helical ribbons made of molecular monolayers and bilayers, whereas strongly deformed stacks of 5–6 layers were found in the bulk samples. The width and pitch of the helical filaments were governed by molecular length; they both increased with terminal‐chain elongation. It was also found that bulk samples were optically active, in contrast to the corresponding gels, which lacked optical activity. The optical activity of samples originated from the internal structure of the crystal layers rather than from the helicity of the filaments. A theoretical model predicts a strong increase in optical activity as the number of layers in the stack increases and its saturation for few layers, thus explaining the smaller optical activity for gels than for bulk samples. A strong increase and redshift in fluorescence was detected in gels as compared to the sol state.
Bifunctional Brønsted Base Catalyzes Direct Asymmetric Aldol Reaction of α‐Keto Amides
Authors: Echave Haizea , López Rosa , Palomo Claudio
Published: February 2016

The first enantioselective direct cross‐aldol reaction of α‐keto amides with aldehydes, mediated by a bifunctional ureidopeptide‐based Brønsted base catalyst, is described. The appropriate combination of a tertiary amine base and an aminal, and urea hydrogen‐bond donor groups in the catalyst structure promoted the exclusive generation of the α‐keto amide enolate which reacted with either non‐enolizable or enolizable aldehydes to produce highly enantioenriched polyoxygenated aldol adducts without side‐products resulting from dehydration, α‐keto amide self‐condensation, aldehyde enolization, and isotetronic acid formation.
An Intrinsically Disordered Peptide Facilitates Non‐Endosomal Cell Entry
Authors: Medina Scott H. , Miller Stephen E. , Keim Allison I. , Gorka Alexander P. , Schnermann Martin J. , Schneider Joel P.
Published: February 2016

Many cell‐penetrating peptides (CPPs) fold at cell surfaces, adopting α‐ or β‐structure that enable their intracellular transport. However, the same structural folds that facilitate cellular entry can also elicit potent membrane‐lytic activity, limiting their use in delivery applications. Further, a distinct CPP can enter cells through many mechanisms, often leading to endosomal entrapment. Herein, we describe an intrinsically disordered peptide (CLIP6) that exclusively employs non‐endosomal mechanisms to cross cellular membranes, while being remarkably biocompatible and serum‐stable. We show that a single anionic glutamate residue is responsible for maintaining the disordered bioactive state of the peptide, defines its mechanism of cellular entry, and is central to its biocompatibility. CLIP6 can deliver membrane‐impermeable cargo directly to the cytoplasm of cells, suggesting its broad utility for delivery of drug candidates limited by poor cell permeability and endosomal degradation.
Catalytic Promiscuity of Transaminases: Preparation of Enantioenriched β‐Fluoroamines by Formal Tandem Hydrodefluorination/Deamination
Authors: Cuetos Aníbal , García‐Ramos Marina , Fischereder Eva‐Maria , Díaz‐Rodríguez Alba , Grogan Gideon , Gotor Vicente , Kroutil Wolfgang , Lavandera Iván
Published: February 2016

Transaminases are valuable enzymes for industrial biocatalysis and enable the preparation of optically pure amines. For these transformations they require either an amine donor (amination of ketones) or an amine acceptor (deamination of racemic amines). Herein transaminases are shown to react with aromatic β‐fluoroamines, thus leading to simultaneous enantioselective dehalogenation and deamination to form the corresponding acetophenone derivatives in the absence of an amine acceptor. A series of racemic β‐fluoroamines was resolved in a kinetic resolution by tandem hydrodefluorination/deamination, thus giving the corresponding amines with up to greater than 99 % ee. This protocol is the first example of exploiting the catalytic promiscuity of transaminases as a tool for novel transformations.
Intramolecular Singlet Fission in Oligoacene Heterodimers
Authors: Sanders Samuel N. , Kumarasamy Elango , Pun Andrew B. , Steigerwald Michael L. , Sfeir Matthew Y. , Campos Luis M.
Published: February 2016

We investigate singlet fission (SF) in heterodimers comprising a pentacene unit covalently bonded to another acene as we systematically vary the singlet and triplet pair energies. We find that these energies control the SF process, where dimers undergo SF provided that the resulting triplet pair energy is similar or lower in energy than the singlet state. In these systems the singlet energy is determined by the lower‐energy chromophore, and the rate of SF is found to be relatively independent of the driving force. However, triplet pair recombination in these heterodimers follows the energy gap law. The ability to tune the energies of these materials provides a key strategy to study and design new SF materials—an important process for third‐generation photovoltaics.
Guest‐Induced Breathing Effect in a Flexible Molecular Crystal
Authors: Sheng Yujie , Chen Qibin , Yao Junyao , Lu Yunxiang , Liu Honglai , Dai Sheng
Published: February 2016

By introducing a flexible component into a molecular building block, we present an unprecedented alkyl‐decorated flexible crystalline material with a breathing behavior. Its selective adsorption is derived from the breathing effect induced by a guest triggered alkyl transformation. This feature allows the crystal to take up 2.5 mmol g−1 of chloroform with high adsorption selectivity (CHCl3/EA >2000 for example), implying a potential application in sorption separation and chemical sensors.
A Rhizavidin Monomer with Nearly Multimeric Avidin‐Like Binding Stability Against Biotin Conjugates
Authors: Lee Jeong Min , Kim Jung A. , Yen Tzu‐Chi , Lee In Hwan , Ahn Byungjun , Lee Younghoon , Hsieh Chia‐Lung , Kim Ho Min , Jung Yongwon
Published: February 2016

Developing a monomeric form of an avidin‐like protein with highly stable biotin binding properties has been a major challenge in biotin‐avidin linking technology. Here we report a monomeric avidin‐like protein—enhanced monoavidin—with off‐rates almost comparable to those of multimeric avidin proteins against various biotin conjugates. Enhanced monoavidin (eMA) was developed from naturally dimeric rhizavidin by optimally maintaining protein rigidity during monomerization and additionally shielding the bound biotin by diverse engineering of the surface residues. eMA allowed the monovalent and nonperturbing labeling of head‐group‐biotinylated lipids in bilayer membranes. In addition, we fabricated an unprecedented 24‐meric avidin probe by fusing eMA to a multimeric cage protein. The 24‐meric avidin and eMA were utilized to demonstrate how artificial clustering of cell‐surface proteins greatly enhances the internalization rates of assembled proteins on live cells.
Ein P‐H‐funktionalisiertes Al/P‐basiertes frustriertes Lewis‐Paar: Substrataktivierung und selektiver Wasserstofftransfer
Authors: Keweloh Lukas , Klöcker M Sc. Hans , Würthwein Ernst‐Ulrich , Uhl Werner
Published: February 2016

Die Hydoaluminierung eines sekundären Alkinylphosphans ergab ein neuartiges P‐H‐funktionalisiertes FLP. Die reaktive P‐H‐Gruppe beeinflusst nicht die typischen FLP‐Eigenschaften, der Aktivierung der Substrate folgt aber in einer neuartigen Reaktionsweise die Übertragung eines Wasserstoffatoms unter Bildung ungewöhnlicher Phosphaharnstoff‐, Iminophosphan‐ oder Phosphanyltriazen‐Derivate.
Modifizierte Nukleotide für die Diskriminierung zwischen Cytosin und dem epigenetischen Marker 5‐Methylcytosin
Authors: von Watzdorf Janina , Leitner Kim , Marx Andreas
Published: February 2016

5‐Methyl‐2′‐desoxycytosin, der häufigste epigenetische DNA‐Marker in eukaryotischen Zellen, spielt eine Schlüsselrolle in der Genregulierung und beeinflusst somit zahlreiche zelluläre Prozesse, wie Entwicklung und Karzinogenese. Daher kann die Detektion von 5mC als wichtiger Biomarker in der Diagnostik fungieren. Wir beschreiben hier, dass modifizierte dGTP‐Analoga, wie auch modifizierte Primer, in der Lage sind, die An‐ oder Abwesenheit einer einzigen Methylierung von C zu detektieren, obwohl diese Modifizierung nicht direkt mit der Watson‐Crick‐Basenpaarung interferiert. Durch das Testen vieler verschiedener Nukleotidgerüste haben wir festgestellt, dass O6‐modifizierte 2′‐Desoxyguanosinanaloga zwischen C und 5mC diskriminieren. Diese modifizierten Nukleotide können in der positionsspezifischen Detektion von 5mC, z. B. bei Echtzeit‐PCR‐Methoden, Anwendung finden.
Synthetic Strategies toward Natural Products Containing Contiguous Stereogenic Quaternary Carbon Atoms
Authors: Büschleb Martin , Dorich Stéphane , Hanessian Stephen , Tao Daniel , Schenthal Kyle B. , Overman Larry E.
Published: February 2016

Strategies for the total synthesis of complex natural products that contain two or more contiguous stereogenic quaternary carbon atoms in their intricate structures are reviewed with 12 representative examples. Emphasis has been put on methods to create quaternary carbon stereocenters, including syntheses of the same natural product by different groups, thereby showcasing the diversity of thought and individual creativity. A compendium of selected natural products containing two or more contiguous stereogenic quaternary carbon atoms and key reactions in their total or partial syntheses is provided in the Supporting Information.
Nanomechanics of Poly(catecholamine) Coatings in Aqueous Solutions
Authors: Lim Chanoong , Huang Jun , Kim Sunjin , Lee Haeshin , Zeng Hongbo , Hwang Dong Soo
Published: February 2016

Mussel‐inspired self‐polymerized catecholamine coatings have been widely utilized as a versatile coating strategy that can be applied to a variety of substrates. For the first time, nanomechanical measurements and an evaluation of the contribution of primary amine groups to poly(catecholamine) coatings have been conducted using a surface‐forces apparatus. The adhesive strength between the poly(catecholamine) layers is 30‐times higher than that of a poly(catechol) coating. The origin of the strong attraction between the poly(catecholamine) layers is probably due to surface salt displacement by the primary amine, π–π stacking (the quadrupole–quadrupole interaction of indolic crosslinks), and cation–π interactions (the monopole–quadrupole interaction between positively charged amine groups and the indolic crosslinks). The contribution of the primary amine group to the catecholamine coating is vital for the design and development of mussel‐inspired catechol‐based coating materials.
Total Syntheses of (+)‐Grandilodine C and (+)‐Lapidilectine B and Determination of their Absolute Stereochemistry
Authors: Nakajima Masaya , Arai Shigeru , Nishida Atsushi
Published: February 2016

Enantioselective total syntheses of the Kopsia alkaloids (+)‐grandilodine C and (+)‐lapidilectine B were accomplished. A key intermediate, spirodiketone, was synthesized in 3 steps and converted into the chiral enone by enantioselective deprotonation followed by oxidation with up to 76 % ee. Lactone formation was achieved through stereoselective vinylation followed by allylation and ozonolysis. The total synthesis of (+)‐grandilodine C was achieved by palladium‐catalyzed intramolecular allylic amination and ring‐closing metathesis to give 8‐ and 5‐membered heterocycles, respectively. Selective reduction of a lactam carbonyl gave (+)‐lapidilectine B. The absolute stereochemistry of both natural products was thereby confirmed. These syntheses enable the scalable preparation of the above alkaloids for biological studies.
Enantioselective Cyanosilylation of Ketones with Lithium(I) Dicyanotrimethylsilicate(IV) Catalyzed by a Chiral Lithium(I) Phosphoryl Phenoxide
Authors: Hatano Manabu , Yamakawa Katsuya , Kawai Tomoaki , Horibe Takahiro , Ishihara Kazuaki
Published: February 2016

A highly enantioselective cyanosilylation of ketones was developed by using a chiral lithium(I) phosphoryl phenoxide aqua complex as an acid/base cooperative catalyst. The pentacoordinate silicate generated in situ from Me3SiCN/LiCN acts as an extremely reactive cyano reagent. Described is a 30 gram scale reaction and the synthesis of the key precursor to (+)‐13‐hydroxyisocyclocelabenzine.
Cobalt(III)‐Catalyzed Redox‐Neutral Synthesis of Unprotected Indoles Featuring an N−N Bond Cleavage
Authors: Lerchen Andreas , Vásquez‐Céspedes Suhelen , Glorius Frank
Published: February 2016

A redox‐neutral cobalt(III)‐catalyzed synthetic approach for the direct synthesis of unprotected indoles showcasing an N−N bond cleavage is reported. The herein newly introduced Boc‐protected hydrazines establish a beneficial addition to the limited portfolio of oxidizing directing groups for cobalt(III) catalysis. Moreover, the developed catalytic methodology tolerates a good variety of functional groups.
Halogen‐Bond‐Templated [2+2] Photodimerization in the Solid State: Directed Synthesis and Rare Self‐Inclusion of a Halogenated Product
Authors: Sinnwell Michael A. , MacGillivray Leonard R.
Published: February 2016

A ditopic halogen‐bond acceptor organizes a diiodooctafluorostilbene for a [2+2] photodimerization reaction to take place between two stilbene molecules in the solid state. The resultant cyclobutane product is functionalized with halogen atoms and undergoes self‐assembly to form a channel‐type host–guest compound that exhibits a very rare form of self‐inclusion.
Experimental and Theoretical Evidence for an Agostic Interaction in a Gold(III) Complex
Authors: Rekhroukh Feriel , Estévez Laura , Bijani Christian , Miqueu Karinne , Amgoune Abderrahmane , Bourissou Didier
Published: February 2016

The first agostic interaction in a gold complex is described. The presence of a bonding C−H⋅⋅⋅Au interaction in a cationic “tricoordinate” gold(III) complex was suggested by DFT calculations and was subsequently confirmed by NMR spectroscopy at low temperature. The agostic interaction was analyzed computationally using NBO and QTAIM analyses (NBO=natural bond orbital; QTAIM=quantum theory of atoms in molecules).
Morphology and dynamical mechanical properties of poly ether ketone ketone (PEKK) with meta phenyl links
Authors: Quiroga Cortés Luis , Caussé Nicolas , Dantras Eric , Lonjon Antoine , Lacabanne Colette
Published: February 2016

Poly ether ketone ketone (PEKK) with different proportion of meta phenyl links were investigated by combining differential scanning calorimetry and dynamic mechanical analysis. The influence of the Terephthalyl/Isophthalyl isomers (T/I) ratio on the vitreous phase is mild, the shift of the glass transition is limited to a few degrees and the vitreous G′ is only sensitive to the content of the crystalline phase. Contrarily, the increase of meta isomers is responsible for a significant decrease of the melting temperature (Tm) by 60 °C, which considerably facilitates processing. The modification of interchain interactions in the crystalline phase might be implied. A series of thermal protocols evidenced that the difference of crystallization behavior is also dependent upon the T/I isomer ratio. A time and temperature dependence of annealing on the double melting behavior of PEKK was observed. Regarding the mechanical behavior, the observed reinforcing effect due to the crystalline phase was more prominent in the rubbery state than in the glassy state. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2016,133, 43396.
Improving properties of silicone rubber composites using macromolecular silane coupling agent (MMSCA)
Authors: Mei Honggang , Chen Guowen , Zhu Qingzeng , Dong Peng , Zhao Dannan , Ahmed Raza Waqas
Published: February 2016

Two types of vinyl silicone oil (VSO), allyl‐capped hyperbranched polycarbosilane (HBP), and triethoxysilane (TES) were employed to synthesize macromolecular silane coupling agent (MMSCA) by hydrosilylation. VSOs, HBP, and the hydrosilylated products were used as crosslinker, respectively, to improve weak mechanical properties of silicone rubber (SR). Structures of the crosslinkers were studied by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR). Crosslinking density test and scanning electron microscope (SEM) observation showed an increased interaction between silicone rubber and fumed silica by the use of MMSCA. Mechanical properties of the resulted composites using MMSCAs were increased to varying degrees compared with those possessing crosslinkers without ethoxy group. MMSCAs were effective for further property enhancements of composites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2016,133, 43415.