bluuebunny/crossref_metadata_2025_split huggingface dataset:
Communautés de pratique et capacité d’absorption des connaissances dans un contexte inter-organisationnel
Authors: Amamou Belkassem , Koubaa Salah 
Published: June 2014

L’objectif de cet article consiste à mettre en relation les communautés de pratique et l’innovation dans un contexte de relations inter-organisationnelles (RIO) en mettant en exergue le rôle de la capacité d’absorption des connaissances. Autrement dit, nous montrons, dans un modèle de recherche, le processus d’influence positive des communautés de pratique sur l’innovation en considérant la capacité d’absorption comme une variable intermédiaire. Les variables relationnelles de confiance et d’engagement sont considérées comme des facteurs explicatifs de la formation des communautés.Pour ce faire, nous sommes partis des théories des ressources, des capacités dynamiques ainsi que du constat du manque de ressources et du management de proximité des PME pour faire apparaître un modèle reliant les variables relationnelles (confiance et engagement), les communautés de pratique, le partage des connaissances, la capacité d’absorption et l’innovation. Nous avons testé les hypothèses de recherche sur un échantillon de 110 PME. Les données collectées sont analysées par la méthode des équations structurelles (LISREL pour les analyses confirmatoires et PLS pour les tests d’hypothèses). Les résultats montrent l’existence d’une relation positive entre les variables relationnelles et l’innovation à travers les notions de communautés de pratique. Cette relation est renforcée par le rôle médiateur de la capacité d’absorption des connaissances.
Subtropical surface layer salinity budget and the role of mesoscale turbulence
Authors: Busecke Julius , Gordon Arnold L. , Li Zhijin , Bingham Frederick M. , Font Jordi 
Published: June 2014

AbstractThe subtropical North Atlantic exhibits the saltiest surface waters of the open ocean. Eventually that water subducted from the surface and exported toward the Equator, as a subsurface salinity maximum (S‐max) forming the lower limb of the subtropical cell. Climatologically, the winter subtropical surface water, coinciding with the deepest mixed layer of ∼100 m, is saltier and colder than the S‐max. Towed CTD measurements in March/April 2013 (a component of the field program SPURS) within the North Atlantic subtropical surface salinity maximum reveal several relatively fresh, warm anomalies, which deviate strongly from climatological conditions. These features introduce a large amount of freshwater into the subtropical region, exceeding the amount introduced by local rain events. Observed scales and evolution of the features strongly suggest a connection to mesoscale dynamics. This is supported by high‐resolution regional model output, which produces an abundance of features that are similar in scale and structure to those observed. It is hypothesized that turbulent transport in the surface ocean is a crucial process for setting mixed layer characteristics, which spread into S‐max stratum. High variability in the EKE implies a high potential for interannual variability in the resulting S‐max water properties by ocean dynamics in addition to the variability caused by air sea fluxes. This has likely consequences to the meridional transport of heat and freshwater of the subtropical cell in the North Atlantic and to the larger‐scale ocean and climate system.
Effect of low‐permeability layers on spatial patterns of hyporheic exchange and groundwater upwelling
Authors: Gomez‐Velez Jesus D. , Krause Stefan , Wilson John L. 
Published: June 2014

AbstractBed form‐induced hyporheic interactions are characterized by a nested system of flow paths that continuously exchange water, solutes, momentum, and energy. At the local scale, sediment heterogeneity plays a key role in the hydrodynamics and potential for biogeochemical transformations within the hyporheic zone. This manuscript explores the role of low‐permeability sedimentary layers on the interplay between bed form‐induced hyporheic exchange and groundwater upwelling. A hydrodynamic conceptualization that sequentially couples fully‐turbulent flow in the water column and Darcian flow in the sediment is used. Low‐permeability layers are characterized by long residence times and solute accumulation. Furthermore, these layers induce hydrodynamic sequestration due to the relocation and, in some cases, emergence of new stagnation zones. Spatial patterns of residence time distributions and flushing intensities indicate that the interface of the low‐permeability layers has the potential to be a hot spot for biogeochemical transformations and flow acceleration near such interface can increase the mobilization capacity for the products of redox chemical and microbial processes. A discussion about the possible implications that hydrodynamic changes have on the biogeochemistry of hyporheic zones is presented; however, further biogeochemical experimentation and modeling are needed to validate these arguments.
Consolidation state of incoming sediments to the Nankai Trough subduction zone: Implications for sediment deformation and properties
Authors: Kitajima Hiroko , Saffer Demian M. 
Published: June 2014

AbstractThe hydromechanical properties of accreted and underthrust sediments are key parameters controlling the mechanics of earthquakes and the development of fluid pressure in subduction zones. We conducted consolidation tests on sediments from the Philippine Sea Plate (PSP) in the Nankai Trough to understand the consolidation state and hydraulic properties of the incoming sediment section before its incorporation into the subduction zone. We used mudstone and sandstone cores sampled from the Integrated Ocean Drilling Program Nankai Trough Seismogenic Zone Experiment at two reference sites (Site C0011 located on a basement low; and Site C0012 located on a basement high). Our experimental results indicate that most of the mudstone samples are normally consolidated or overconsolidated, with overconsolidation ratios (OCR) ranging from 0.89 to 2.52 at Site C0011 and 0.86 to 3.85 at Site C0012. Higher OCR values at Site C0012, at least at shallow depths, are likely caused by erosional unloading. This implies that Site C0011 may serve as a better geotechnical reference site. We also find that mudstones accreted along the frontal thrust are severely overconsolidated relative to coeval mudstones at Site C0011, which likely reflects enhanced consolidation due to increased horizontal tectonic stress. Sandstones in the incoming section on the PSP exhibit 2–3 orders of magnitude higher in situ permeability than the mudstones, and the siliciclastic sandstone we tested maintains a high permeability at stresses up to at least 70 MPa, suggesting that the sandstones may act as important pathways for drainage or pore pressure translation from depths of several kilometers.
Observations of pronounced Greenland ice sheet firn warming and implications for runoff production
Authors: Polashenski Chris , Courville Zoe , Benson Carl , Wagner Anna , Chen Justin , Wong Gifford , Hawley Robert , Hall Dorothy 
Published: June 2014

AbstractField measurements of shallow borehole temperatures in firn across the northern Greenland ice sheet are collected during May 2013. Sites first measured in 1952–1955 are revisited, showing long‐term trends in firn temperature. Results indicate a pattern of substantial firn warming (up to +5.7°C) at midlevel elevations (1400–2500 m) and little temperature change at high elevations (>2500 m). We find that latent heat transport into the firn due to meltwater percolation drives the observed warming. Modeling shows that heat is stored at depth for several years, and energy delivered from consecutive melt events accumulates in the firn. The observed warming is likely not yet in equilibrium with recent melt production rates but captures the progression of sites in the percolation facies toward net runoff production.
Nontrivial decay of aftershock density with distance in Southern California
Authors: Moradpour Javad , Hainzl Sebastian , Davidsen Jörn 
Published: June 2014

AbstractThe decay of the aftershock density with distance plays an important role in the discussion of the dominant underlying cause of earthquake triggering. Here, we provide evidence that its form is more complicated than typically assumed and that in particular a transition in the power law decay occurs at length scales comparable to the thickness of the crust. This is supported by an analysis of a very recent high‐resolution catalog for Southern California (SC) and surrogate catalogs generated by the Epidemic‐Type Aftershock Sequence (ETAS) model, which take into account inhomogeneous background activity, short‐term aftershock incompleteness, anisotropic triggering, and variations in the observational magnitude threshold. Our findings indicate specifically that the asymptotic decay in the aftershock density with distance is characterized by an exponent larger than 2, which is much bigger than the observed exponent of approximately 1.35 observed for shorter distances ranging from the main shock rupture length up to a length scale comparable to the thickness of the crust. This has also important consequences for time‐dependent seismic hazard assessment based on the ETAS model.
Interrelations between anthropometric and fitness changes during mid‐adolescence in boys: A 2‐year longitudinal study
Authors: Gerber Barend P. , Pienaar Anita E. , Kruger Ankebe , Ellis Suria 
Published: June 2014

ObjectivesThis study aimed to determine changes and interrelationships between changes in selected anthropometric growth parameters and motor and physical fitness, among boys over a 2 year period during mid‐adolescence.MethodsSpeed, agility, hand‐eye coordination, explosive power, muscle strength, and aerobic endurance were measured once a year, and the anthropometric measurements (stature, body mass, sitting height, arm span, and sitting height ratio), were measured three times per year, 4 months apart (among 73 adolescent boys). A hierarchical linear model, adjusting for covariates and partial correlation analysis (R2) were used to analyze the data.ResultsAll anthropometric, motor, and physical measurements improved significantly over the two‐year period. Significantly, greater changes were seen between 13 and 14 years in stature, arm span, sitting height and body mass. Changes in muscle strength, speed and agility were mainly significant between 13 and 14 years while the biggest changes occurred in explosive power and upper‐body‐arm‐and‐shoulder‐strength during year 2 (14–15 years).The majority of interrelationships, indicating moderate to small relationships, were found between changes in stature, arm span, and sitting height, and changing strength, speed, agility, and hand eye coordination over the two‐year period, after adjusting for maturity age and physical activity levels.ConclusionMotor and physical fitness improved significantly from 13 to 15 years, showing definite interrelationships with anthropometric growth during the mid‐adolescence period. Awareness and education about these changes are recommended as it can have significant effects on the sport performance and fitness training of boys during mid‐adolescence. Am. J. Hum. Biol. 26:617–626, 2014. © 2014 Wiley Periodicals, Inc.
Simultaneous enhancement of excitation and postburst inhibition at the end of focal seizures
Authors: Boido Davide , Gnatkovsky Vadym , Uva Laura , Francione Stefano , de Curtis Marco 
Published: June 2014

ObjectiveComprehension of the events that lead to seizure termination contributes to the development of strategies to confine propagation of ictal discharges. It is commonly assumed that the inhibitory control fails during seizures and recovers after the end of the ictal event. We examine the possibility that a progressive increase of inhibition that counters an increase in the strength of excitation contributes to terminating a focal seizure.MethodsWe analyzed seizures acutely induced by pharmacological manipulations (bicuculline and 4‐aminopyridine) in the entorhinal cortex and in the hippocampus of the in vitro isolated guinea pig brain.ResultsAs seizures ended, extracellular and intracellular recordings showed periodic bursting that progressively decreased in frequency. During the late bursting phase, the duration, number, and rate of occurrence of spikes within single bursts remained constant, whereas cumulative spike amplitude (index of excitation during a burst) and interburst interval (index of inhibition between bursts) progressively increased. The increment of average/cumulative burst excitation and interburst interval toward seizure end was confirmed in human focal seizures recorded with intracerebral electrodes in patients with drug‐resistant partial epilepsies. A postburst refractory period of circa 2 seconds that increases with time toward the end of the seizure was confirmed in the experimental model by probing interburst epochs in the CA1 region with local dentate gyrus stimulation just suprathreshold for burst generation.InterpretationOur findings support the concept that focal seizures are terminated by the simultaneous and opposing enhancement of excitation (burst activity) in addition to postburst inhibition. We hypothesize that a seizure stops when postburst inhibition becomes large enough to prevent reactivation of excitation. Ann Neurol 2014;76:826–836
Chaotropic‐Anion‐Induced Supramolecular Self‐Assembly of Ionic Polymeric Micelles
Authors: Li Yang , Wang Yiguang , Huang Gang , Ma Xinpeng , Zhou Kejin , Gao Jinming 
Published: June 2014

AbstractTraditional micelle self‐assembly is driven by the association of hydrophobic segments of amphiphilic molecules forming distinctive core–shell nanostructures in water. Here we report a surprising chaotropic‐anion‐induced micellization of cationic ammonium‐containing block copolymers. The resulting micelle nanoparticle consists of a large number of ion pairs (≈60 000) in each hydrophobic core. Unlike chaotropic anions (e.g. ClO4−), kosmotropic anions (e.g. SO42−) were not able to induce micelle formation. A positive cooperativity was observed during micellization, for which only a three‐fold increase in ClO4− concentration was necessary for micelle formation, similar to our previously reported ultra‐pH‐responsive behavior. This unique ion‐pair‐containing micelle provides a useful model system to study the complex interplay of noncovalent interactions (e.g. electrostatic, van der Waals, and hydrophobic forces) during micelle self‐assembly.
Additive Effects in the Palladium‐Catalyzed Carboiodination of Chiral N‐Allyl Carboxamides
Authors: Petrone David A. , Yoon Hyung , Weinstabl Harald , Lautens Mark 
Published: June 2014

AbstractThe use of Pd catalysis as a means to synthesize organic halides has recently received increased attention. Among the reported methods is the Pd‐catalyzed carboiodination, which uses extremely bulky ligands to facilitate carbon–halogen reductive elimination from PdII as the key catalytic step. When approaching substrates exhibiting low stereoselectivity, catalyst troubleshooting becomes difficult as there are few ligands known to promote the key reductive elimination. Herein, we present our finding that tertiary amines act as weakly coordinating ligands which significantly enhance diastereoselectivity in the Pd/QPhos‐catalyzed carboiodination of chiral N‐allyl carboxamides. This methodology allows efficient access to enantioenriched and densely functionalized dihydroisoquinolinones, and has been applied toward the asymmetric formal synthesis of (+)‐corynoline.
Asymmetric, Stereodivergent Synthesis of (−)‐Clusianone Utilizing a Biomimetic Cationic Cyclization
Authors: Boyce Jonathan H. , Porco John A. 
Published: June 2014

AbstractWe report a stereodivergent, asymmetric total synthesis of (−)‐clusianone in six steps from commercial materials. We implement a challenging cationic cyclization forging a bond between two sterically encumbered quaternary carbon atoms. Mechanistic studies point to the unique ability of formic acid to mediate the cyclization forming the clusianone framework.
Asymmetric Synthesis of Isoindolones by Chiral Cyclopentadienyl‐Rhodium(III)‐Catalyzed CH Functionalizations
Authors: Ye Baihua , Cramer Nicolai 
Published: June 2014

AbstractDirected Cp*RhIII‐catalyzed carbon–hydrogen (CH) bond functionalizations have evolved as a powerful strategy for the construction of heterocycles. Despite their high value, the development of related asymmetric reactions is largely lagging behind due to a limited availability of robust and tunable chiral cyclopentadienyl ligands. Rhodium complexes comprising a chiral Cp ligand with an atropchiral biaryl backbone enables an asymmetric synthesis of isoindolones from arylhydroxamates and weakly alkyl donor/acceptor diazo derivatives as one‐carbon component under mild conditions. The complex guides the substrates with a high double facial selectivity yielding the chiral isoindolones in good yields and excellent enantioselectivities.
The Formation of Pyrroline and Tetrahydropyridine Rings in Amino Acids Catalyzed by Pyrrolysine Synthase (PylD)
Authors: Quitterer Felix , Beck Philipp , Bacher Adelbert , Groll Michael 
Published: June 2014

AbstractThe dehydrogenase PylD catalyzes the ultimate step of the pyrrolysine pathway by converting the isopeptide L‐lysine‐Nε‐3R‐methyl‐D‐ornithine to the 22nd proteinogenic amino acid. In this study, we demonstrate how PylD can be harnessed to oxidize various isopeptides to novel amino acids by combining chemical synthesis with enzyme kinetics and X‐ray crystallography. The data enable a detailed description of the PylD reaction trajectory for the biosynthesis of pyrroline and tetrahydropyridine rings as constituents of pyrrolysine analogues.
Cyclodextrin‐Templated Porphyrin Nanorings
Authors: Liu Pengpeng , Neuhaus Patrik , Kondratuk Dmitry V. , Balaban T. Silviu , Anderson Harry L. 
Published: June 2014

Abstractα‐ and β‐Cyclodextrins have been used as scaffolds for the synthesis of six‐ and seven‐legged templates by functionalizing every primary CH2OH with a 4‐pyridyl moiety. Although these templates are flexible, they are very effective for directing the synthesis of macrocyclic porphyrin oligomers consisting of six or seven porphyrin units. The transfer of chirality from the cyclodextrin templates to their nanoring hosts is evident from NMR and circular dichroism spectroscopy. Surprisingly, the mean effective molarity for binding the flexible α‐cyclodextrin‐based template within the six‐porphyrin nanoring (74 M) is almost as high as for the previously studied rigid hexadentate template (180 M). The discovery that flexible templates are effective in this system, and the availability of a template with a prime number of binding sites, open up many possibilities for the template‐directed synthesis of larger macrocycles.
Covalent Hypercoordination: Can Carbon Bind Five Methyl Ligands?
Authors: McKee William C. , Agarwal Jay , Schaefer Henry F. , Schleyer Paul von R. 
Published: June 2014

AbstractC(CH3)5+is the first reported example of a five‐coordinate carbon atom bound only to separate (that is, monodentate) carbon ligands. This species illustrate the limits of carbon bonding, exhibiting Lewis‐violating “electron‐deficient bonds” between the hypercoordinate carbon and its methyl groups. Though not kinetically persistent under standard laboratory conditions, its dissociation activation barriers may permit C(CH3)5+fleeting existence near 0 K.
Isolation of a Neutral Boron‐Containing Radical Stabilized by a Cyclic (Alkyl)(Amino)Carbene
Authors: Bissinger Philipp , Braunschweig Holger , Damme Alexander , Krummenacher Ivo , Phukan Ashwini K. , Radacki Krzysztof , Sugawara Shun 
Published: June 2014

AbstractUtilizing a cyclic (alkyl)(amino)carbene (CAAC) as a ligand, neutral CAAC‐stabilized radicals containing a boryl functionality could be prepared by reduction of the corresponding haloborane adducts. The radical species with a duryl substituent was fully characterized by single‐crystal X‐ray structural analysis, EPR spectroscopy, and DFT calculations. Compared to known neutral boryl radicals, the isolated radical species showed larger spin density on the boron atom. Furthermore, the compound that was isolated is extraordinarily stable to high temperatures under inert conditions, both in solution and in the solid state. Electrochemical investigations of the radical suggest the possibility to generate a stable formal boryl anion species.
Morphology, physical properties, silver release, and antimicrobial capacity of ionic silver‐loaded poly(l‐lactide) films of interest in food‐coating applications
Authors: Martínez‐Abad Antonio , Ocio María José , Lagaron José María 
Published: June 2014

ABSTRACTIn the present study, silver ions were incorporated into a poly‐(l‐lactide) (PLA) matrix by a solvent casting technique using different solvents and glycerol as plasticizer. The effect of the different formulations on the morphology, thermal, mechanical and color properties were first evaluated. Additionally, a thorough study of the silver ions release to an aqueous environment was also monitored over time by anodic stripping voltammetry and correlated with the antimicrobial performance against S. enterica. The incorporation of silver contents of up to 1 wt % did not affect morphology, thermal or mechanical properties of the films. A sustainable, antibacterial effectiveness was found for the films in liquid medium and a breakpoint of 10–20 μg L−1 silver was established under the stated conditions, evincing silver ion releasing technologies may be applied to liquid environments while complying with current legislation. This study provides insight into the structure properties relationship of these antibacterial polylactide materials of significant potential in coating applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41001.
Simultaneous adsorptive removal of methylene blue and copper ions from aqueous solution by ferrocene‐modified cation exchange resin
Authors: Wang Qian , Zhang Dehua , Tian Senlin , Ning Ping 
Published: June 2014

ABSTRACTResin was modified with ferrocene (Fc) to enhance removal of Methylene Blue (MB) and Cu2+ from simulated wastewater. The FTIR, N2‐BET, and X‐ray fluorescence analysis confirmed that Fc was successfully grafted onto the surface of resin. The adsorption capacity of Fc modified cation exchange resin (FMCER) was calculated to be 392.16 mg/g Cu2+ and 10.01 mg/g MB. Both processes were spontaneous and exothermic, best described by Langmuir equation. Pseudo‐first‐order kinetic model satisfied the adsorption of MB, while the intraparticle‐diffusion model fitted the kinetics of Cu2+ adsorption best. The result revealed a multilayer adsorption of Cu2+ on FMCER, and the kinetics maybe controlled by intraparticle diffusion, film diffusion, and competition force. The adsorption of MB and Cu2+ on FMCER were physicosorptive, with activation energies of 2.09 and 1.27 kJ/mol. pH 2–7 and 4–5 are optimum for the removal of MB and Cu2+, and pH 4 is optimal for the simultaneous removal of MB and Cu2+. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41029.