bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enantioselective Carbene Cascade: An Effective Approach to Cyclopentadienes and Applications in Diels–Alder Reactions
Authors: Wang Xiangbo , Zhou Yunfei , Qiu Lihua , Yao Ruwei , Zheng Yang , Zhang Cheng , Bao Xiaoguang , Xu Xinfang 
Published: April 2016

AbstractAn asymmetric carbene cascade reaction, which proceeds through carbene/alkyne metathesis and formal (3+2) cycloaddition and converts alkynyl‐tethered enol diazoacetates to chiral bicyclic cyclopentadienes, is presented; and no catalytic asymmetric version of these carbene cascade transformations has been disclosed so far. The proton signals of the cyclopropene intermediates are observed in the mechanism study, which clearly demonstrate the reaction pathways. In addition, these products are intercepted via Diels–Alder reactions to provide bridged polycyclic structures in high yields and enantioselectivities.magnified image
(Pentamethylcyclopentadienyl)cobalt(III)‐Catalyzed Oxidative [4+2] Annulation of NH Imines with Alkynes: Straightforward Synthesis of Multisubstituted Isoquinolines
Authors: Zhang Shang‐Shi , Liu Xu‐Ge , Chen Shi‐Yong , Tan Dong‐Hang , Jiang Chun‐Yong , Wu Jia‐Qiang , Li Qingjiang , Wang Honggen 
Published: April 2016

AbstractA synthetic method for isoquinoline synthesis via a [4+2] annulation of NH imines with alkynes using the high‐valent (pentamethylcyclopentadienyl)cobalt(III) [Cp*Co(III)] catalyst is described. Cerium(IV) sulfate was found to be an efficient oxidant in lieu of the commonly used copper or silver salts. Broad substrate scope, high functional group tolerance, and generally good yields were observed.magnified image
Mapping the Social World of Classrooms: A Multi‐Level, Multi‐Reporter Approach to Social Processes and Behavioral Engagement
Authors: Kim Ha Yeon , Cappella Elise 
Published: April 2016

AbstractUnderstanding the social context of classrooms has been a central goal of research focused on the promotion of academic development. Building on the current literature on classroom social settings and guided by a risk and protection framework, this study examines the unique and combined contribution of individual relationships and quality of classroom interactions on behavioral engagement among low‐income Latino students in kindergarten to fifth grade (N = 111). Findings indicate that individual relationships with teachers and peers and classroom quality, each independently predicted behavioral engagement. Moreover, high‐quality classrooms buffered the negative influence of students’ difficulties in individual relationships on behavioral engagement. Findings illuminate the need to consider multiple layers of social classroom relationships and interactions and suggest the potential benefit of targeting classroom quality as a mechanism for improving behavioral engagement in urban elementary schools.
Intrazelluläre Visualisierung der Entstehung von Poly(ADP‐Ribose) mit bioorthogonal funktionalisierten NAD+‐Analoga
Authors: Wallrodt Sarah , Buntz Annette , Wang Yan , Zumbusch Andreas , Marx Andreas 
Published: April 2016

AbstractPoly(ADP‐ribos)ylierung (PARylierung) ist eine wichtige posttranslationale Proteinmodifikation und ein bedeutender Signalweg in fast allen Eukaryoten. Grundlegende Prozesse, wie DNA‐Reparatur und Transkription, werden von diesem kurzlebigen Polymer und seiner Wechselwirkung mit Proteinen gesteuert. ADP‐Ribosyltransferasen (ARTs) erzeugen komplizierte ADP‐Riboseketten aus NAD+ an diversen Akzeptorproteinen, weshalb die Erforschung der PARylierung auf molekularer Ebene anspruchsvoll ist. Hier präsentieren wir die Entwicklung bioorthogonal funktionalisierter NAD+‐Analoga für die In‐vitro‐ und In‐cellulo‐Detektion der PARylierung. Für die intrazelluläre Visualisierung der PARylierung, zeitgleich und in zwei Farben, eignen sich besonders an Position 2 modifizierte NAD+‐Analoga. Diese geben Einblick in das Substratspektrum der ARTs und werden durch schnelles optisches sowie mehrfarbiges Auslesen von PARylierungen zur Aufklärung der biologischen Funktionen dieser Prozesse beitragen.
Asymmetric Conjugate Addition of Benzofuran‐2‐ones to Alkyl 2‐Phthalimidoacrylates: Modeling Structure–Stereoselectivity Relationships with Steric and Electronic Parameters
Authors: Yang Chen , Zhang En‐Ge , Li Xin , Cheng Jin‐Pei 
Published: April 2016

AbstractA highly predictive model to correlate the steric and electronic parameters of tertiary amine thiourea catalysts with the stereoselectivity of Michael reactions of 3‐substituted benzofuranones and alkyl 2‐phthalimidoacrylates is described. As predicted, new 3,5‐bis(trifluoromethyl)benzyl‐ and methyl‐substituted tertiary amine thioureas turned out to be highly suitable catalysts for this reaction and enabled the synthesis of enantioenriched α‐amino acid derivatives with 1,3‐nonadjacent stereogenic centers.
Electrical conductivity and mechanical performance of multiwalled CNT‐filled polyvinyl chloride composites subjected to tensile load
Authors: Yazdani Hessam , Smith Benjamin E , Hatami Kianoosh 
Published: April 2016

ABSTRACTThis article reports a study on the strain‐sensitive conductivity (tensoresistivity) and mechanical properties of polyvinyl chloride/multiwalled carbon nanotube (PVC/MWCNT) composites subjected to tensile loading at different strain rates for potential use in sensor‐enabled geosynthetics and other applications involving electrically conductive polymer composites. Results indicate that adding 0.5 wt % MWCNT to the composite results in 57% reduction in its ultimate (failure) strain and a fivefold increase in its tensile modulus while leaving its ultimate strength almost unchanged. Laser scanning confocal microscopy is used to investigate the microscopic failure mechanism of the composite and how it contributes to the strain‐sensitive conductivity of the composites. It is observed that tensile fractures are initiated from inside the largest bundles between 18% and 36% strain and continue through further fractal‐like fracturing in smaller bundles. Gauge factors (e.g., 3.17) comparable to or exceeding those of typical strain gauges are obtained for the composite, indicating its strong potential for structural performance monitoring and damage detection applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43665.
Mechanical and open hole tensile properties of self‐reinforced PET composites with recycled PET fiber reinforcement
Authors: Wu Chang‐Mou , Lai Wen‐You 
Published: April 2016

ABSTRACTThe tensile strength of notched composites is an important factor for composite structural design. However, no literature is available on the notch sensitivity of self‐reinforced polymer composites. In this study, self‐reinforced recycled poly (ethylene terephthalate) (srrPET) composites were produced by film stacking from fabrics composed of double covered uncommingled yarns (DCUY). Composite specimens were subjected to uniaxial tensile, flexural, and Izod impact tests and the related results compared with earlier ones achieved on srPET composites reinforced with nonrecycled technical PET fibers. Effects of open circular holes on the tensile strength of srrPETs were studied at various width‐to‐hole diameter (W/D) ratios of the specimens. In the open hole tensile (OHT) measurements bilinear (yielding followed by post‐yield hardening) stress–strain curves were recorded. The srrPET composites had extremely high yield strength retention (up to 142%) and high breaking strength retention (up to 81%) due to the superior ductile nature of the srrPETs, which induces plastic yielding near the hole thereby reducing the stress concentration effect. The results proved that srrPET composites are tough, ductile notch‐insensitive materials. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43682.
Conformal electrodeposition of poly(phenylene oxide) on TiO2 nanotube arrays with high performance for lithium ion battery
Authors: Duan Jixiang , Hou Hongying , Liu Xianxi , Liao Qishu , Liu Song , Meng Ruijin , Hao Zhenliang , Yao Yuan 
Published: April 2016

ABSTRACTIn order to improve electrochemical performances of lithium ion battery (LIB), electrochemical integration of the membrane with the electrode was accomplished by conformal electrodeposition of poly(phenylene oxide) (PPO) on three‐dimensional (3D) oriented TiO2 nanotube arrays (TiO2NT). The as‐synthesized PPO/TiO2NT membrane/electrode was investigated in terms of AC impedance, XPS, SEM, EDX, galvanostatic charge/discharge, rate performance, and cycle stability. As expected, PPO was indeed combined with TiO2NT via conformal electrodeposition; furthermore, the integrated PPO/TiO2NT membrane/electrode delivered much better rate performance than the traditional membrane/electrode, mainly attributed to large area of membrane/electrode/electrolyte, short ionic diffusion paths and fast ionic transport. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43685.
Polymer‐based nucleation for chemical vapour deposition of diamond
Authors: Domonkos Mária , Ižák Tibor , Kromka Alexander , Varga Marián 
Published: April 2016

ABSTRACTChemical vapour deposition of diamond on foreign substrates is hindered due to its high surface energy. Therefore, nucleation treatment has to be employed to initialize the formation of diamond crystals. This article deals with diamond growth on silicon substrates coated with three types of polymers: (i) polystyrene (PS), (ii) polylactic‐co‐glycolic acid (PLGA), and (iii) polyvinyl alcohol (PVA) were applied in different forms, i.e., microspheres (PS, PLGA), monolayers (PLGA), multilayers (PLGA, PLGA/PS), and composites with embedded diamond nanoparticles (PLGA, PVA). Thin polymers and microsphere monolayers did not contribute to the diamond nucleation and/or growth. A thicker continuous polymer film (>750 nm) or thin polymer/microsphere layer led to a homogeneous and dense formation of diamond grains. In the case of nucleation using polymer composites, where the thin polymer film serves as a 3D carrier matrix for embedded diamond nanoparticles, a comparable nucleation density to the well‐established ultrasonic seeding method was achieved. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43688.
Quercetin and curcumin in nanofibers of polycaprolactone and poly(hydroxybutyrate‐co‐hydroxyvalerate): Assessment of in vitro antioxidant activity
Authors: da Silva Uebel Lívia , Angelica Schmatz Daiane , Goettems Kuntzler Suelen , Lima Dora Cristiana , Luiza Muccillo‐Baisch Ana , Alberto Vieira Costa Jorge , Greque de Morais Michele 
Published: April 2016

ABSTRACTPolymeric nanofibers are materials that can be used as scaffolds in tissue engineering. Quercetin and curcumin are antioxidants because of scavenge free radicals and chelate metal ions properties, protecting tissues of lipid peroxidation. The objective of this study was to develop a scaffold with potential antioxidant activity that was produced from nanofibers consisting of polycaprolactone (PCL) and a blend of PCL/poly(hydroxybutyrate‐co‐hydroxyvalerate) (PHB‐HV) with the addition of quercetin or curcumin as the bioactive compound. Curcumin and quercetin were integrated into the solution at a concentration of 3%. The electrospun nanofibers were characterized using calorimetry and thermogravimetric analysis, and the addition of bioactive compounds did not alter the thermal properties of the biomaterial. The antioxidant activity of scaffolds with the active compounds was evaluated by hydrate 2,2‐diphenyl‐2‐picrylhydrazyl (DPPH) and 2,2′‐azinobis (3‐ethylbenzothiazoline‐6‐sulfonic acid) diammonium salt (ABTS) methods. The scaffolds with PCL and PCL/PHB‐HV blend with quercetin exhibited higher antioxidant activity than curcumin with both methods. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43712.
The blood supply to the canine middle ear
Authors: Stevens‐Sparks Cathryn , Jarrett Keith , McNulty Margaret A. , Strain George M. 
Published: April 2016

ABSTRACTCurrent descriptions of the anatomy of the blood supply to the canine middle ear are either incomplete or inconsistent, particularly in regards to the vascular branches in close proximity to the temporomandibular articulation (TMJ). To further investigate this blood supply, dissections (n = 9), corrosion casts (n = 4), and computed tomography (n = 8) of canine temporal regions/ears were performed. The goal of this study was to identify and describe branches of the external carotid and maxillary arteries in close proximity to the TMJ that supply the middle ear of the dog. Specific focus was placed on the constancy and origin of the canine rostral tympanic artery since this artery was anticipated to arise from the maxillary artery and enter a foramen at the medial aspect of the mandibular fossa adjacent to the TMJ. New anatomical variations of three canine arteries are described in this study. (1) The rostral tympanic artery is a branch of the temporomandibular ramus and is accommodated by a small foramen located within a depression medial to the temporomandibular joint. (2) A pharyngeal branch of the caudal deep temporal artery was identified. (3) The origin of the caudal auricular artery occurred opposite the lingual artery in 25.8% of dissected specimens, contrary to published descriptions. Anat Rec, 299:907–917, 2016. © 2016 Wiley Periodicals, Inc.
Spectroscopy and molecular docking study on the interaction of daidzein and genistein with pepsin
Authors: Nan Guanjun , Wang Ping , Sun Jing , Lv Jianhua , Ding Meiwen , Yang Liu , Li Yiping , Yang Guangde 
Published: April 2016

AbstractThe interaction of pepsin with daidzein (Dai) or genistein (Gen) was investigated using spectroscopic techniques under simulated physiological conditions. Dai and Gen can quench the fluorescence of pepsin and the quenching mechanism was a static process. The binding site number n and apparent binding constant K were measured at different temperatures. The thermodynamic parameters ΔΗ, ΔG and ΔS were calculated. The results indicated that van der Waals forces and hydrogen bond formation played major roles in the interaction of Dai or Gen with pepsin. The binding distance between pepsin and Dai or Gen was calculated according to energy transfer theory. The results of synchronous fluorescence spectra showed that the microenvironment and conformation of pepsin were changed. UV absorption and 3D fluorescence spectra showed that the binding interaction disturbed the microenvironment of amino acid residues and induced conformational changes in pepsin. Molecular docking results showed that Dai and Gen entered into the hydrophobic cavity of pepsin and two hydrogen bonds formed between Dai or Gen and pepsin. The results demonstrated that the interaction behavior between Dai and Gen with pepsin was slightly different, which denoted that the 5‐hydroxyl group of Gen, to a certain extent, had an effect on ligand binding to proteins. Copyright © 2016 John Wiley & Sons, Ltd.
Das Geheimnisdes Storchenflugs
Authors: Eder Heinrich , Fiedler Wolfgang , Neuhäuser Markus 
Published: April 2016

AbstractMittels des lasergestützten Zielverfolgungssystems VECTOR IV wurden zahlreiche Flugbahnvermessungen von im freien Flug gleitenden Störchen durchgeführt. Aus den Messdaten konnten die Gleitbahnen rekonstruiert sowie die arteigenen Flug‐ und Sinkgeschwindigkeiten berechnet werden. Darüber hinaus wurden zahlreiche morphometrische Untersuchungen, wie Bestimmungen der Flügelspannweite und der Flügelstreckung im Flug mittels photographischer Verfahren sowie die Gewichtsbestimmung von 36 erwachsenen Störchen mittels einer Außenwaage durchgeführt. Außerdem wurden einzelne Schwungfedern im Windkanal vermessen. Aus den Flugbahnvermessungen und den morphometrischen Daten ließ sich durch mathematische Verfahren der Widerstand anteilig als induzierter Widerstand und nicht induzierter Widerstand (Reibungswiderstand) bestimmen. Verglichen mit einem idealen ebenen Flugzeugflügel weisen Störche im Segelflug bei voll aufgefächerter Spaltflügelkaskade einen rd. 20 % geringeren induzierten Widerstand auf.
Escherichia coli – ein Darmbakterium wird zum Weltstar
Authors: Tetsch Larissa 
Published: April 2016

AbstractAls Erstbesiedler des menschlichen Darms ebnet E. coli den Weg für die obligat anaerobe Darmflora und verhindert die Ansiedlung pathogener Keime. Diese Schutzwirkung machen sich probiotische Arzneimittel mit lebenden E. coli‐Zellen zunutze. Seit der Geburtsstunde der Gentechnik entwickelte sich das Bakterium zum Modellorganismus der Forschung und dient heute zur Produktion unzähliger rekombinanter Proteine wie Hormone und Antikörper.
Die Zippammer – mediterraner Charaktervogel in steilen Weinbergslagen
Authors: Petrischak Hannes 
Published: April 2016

AbstractDie trockenwarmen, steinigen Weinberge am Rhein und seinen Nebenflüssen sind geprägt von einer Reihe wärmeliebender Tier‐ und Pflanzenarten, deren Verbreitungsschwerpunkt im Mittelmeerraum liegt. Dazu zählen beispielsweise Mauereidechse (Podarcis muralis) und Felsenahorn (Acer monspessulanum). Regelmäßiger Begleiter auf Wanderungen durch diese einzigartigen Landschaften ist auch die Zippammer (Emberiza cia), die von den felsigen Gebirgs‐ und Steppenregionen Südeuropas bis hierher vorkommt.
“Arctic apples” – transgene Äpfel, die nicht braun werden
Authors: Högermann Christiane 
Published: April 2016

AbstractIn Kanada und den USA stehen gentechnisch veränderte Äpfel vor der Markteinführung, bei denen durch Manipulation der entsprechenden RNA‐Sequenzen die Bildung der Phenoloxidase blockiert wird. Dieses Enzym führt infolge der Oxidation mit Luftsauerstoffradikalen zum Braunwerden der Apfelschnitze.
Scharf kalkulierende Jäger
Authors: Sander Johannes 
Published: April 2016

AbstractCarnivore Pflanzen bessern ihre Nährstoffversorgung durch das Einfangen und Verdauen von Tieren auf. Da dieser Prozess aber auch Kosten verursacht, müssen die Pflanzen sehr wirtschaftlich vorgehen – zum Beispiel, indem sie die Menge an Verdauungsenzymen genau an die jeweilige Beute anpassen. Wie sie dies machen, wurde jetzt am Beispiel der Venusfliegenfalle untersucht.
Siedeverzug – die unterschätzte Gefahr
Authors: Hauk Andrea 
Published: April 2016

AbstractKennen Sie das? Wieder einmal haben Sie vor lauter Arbeit vergessen, Ihren Tee zu trinken und er steht jetzt kalt auf dem Schreibtisch. Kein Problem – es gibt ja die Mikrowelle im Aufenthaltsraum. Gespannt beobachten Sie das gefüllte Teeglas. Nach wenigen Minuten nehmen Sie den Tee vorsichtig mit einem Tuch heraus. Komisch. Keine Blubberbläschen zu sehen, obwohl er siedend heiß sein müsste. Was Sie jetzt auf keinen Fall tun sollten – das Glas schwenken und Luft auf die Flüssigkeitsoberfläche pusten. Sonst ... whhhooaaamm!
A simultaneous determination method for 5‐fluorouracil and its metabolites in human plasma with linear range adjusted by in‐source collision‐induced dissociation using hydrophilic interaction liquid chromatography–electrospray ionization–tandem mass spectrometry
Authors: Ishii Hideaki , Shimada Miki , Yamaguchi Hiroaki , Mano Nariyasu 
Published: April 2016

AbstractWe applied a new technique for quantitative linear range shift using in‐source collision‐induced dissociation (CID) to complex biological fluids to demonstrate its utility. The technique was used in a simultaneous quantitative determination method of 5‐fluorouracil (5‐FU), an anticancer drug for various solid tumors, and its metabolites in human plasma by liquid chromatography–electrospray ionization–tandem mass spectrometry (LC/ESI‐MS/MS). To control adverse effects after administration of 5‐FU, it is important to monitor the plasma concentration of 5‐FU and its metabolites; however, no simultaneous determination method has yet been reported because of vastly different physical and chemical properties of compounds. We developed a new analytical method for simultaneously determining 5‐FU and its metabolites in human plasma by LC/ESI‐MS/MS coupled with the technique for quantitative linear range shift using in‐source CID. Hydrophilic interaction liquid chromatography using a stationary phase with zwitterionic functional groups, phosphorylcholine, was suitable for separation of 5‐FU from its nucleoside and interfering endogenous materials. The addition of glycerin into acetonitrile‐rich eluent after LC separation improved the ESI‐MS response of high polar analytes. Based on the validation results, linear range shifts by in‐source CID is the reliable technique even with complex biological samples such as plasma. Copyright © 2016 John Wiley & Sons Ltd.
Pruning or tuning? Maturational profiles of face specialization during typical development
Authors: Zhu Xun , Bhatt Ramesh S. , Joseph Jane E. 
Published: April 2016

AbstractIntroductionFace processing undergoes significant developmental change with age. Two kinds of developmental changes in face specialization were examined in this study: specialized maturation, or the continued tuning of a region to faces but little change in the tuning to other categories; and competitive interactions, or the continued tuning to faces accompanied by decreased tuning to nonfaces (i.e., pruning).MethodsUsing fMRI, in regions where adults showed a face preference, a face‐ and object‐specialization index were computed for younger children (5–8 years), older children (9–12 years) and adults (18–45 years). The specialization index was scaled to each subject's maximum activation magnitude in each region to control for overall age differences in the activation level.ResultsAlthough no regions showed significant face specialization in the younger age group, regions strongly associated with social cognition (e.g., right posterior superior temporal sulcus, right inferior orbital cortex) showed specialized maturation, in which tuning to faces increased with age but there was no pruning of nonface responses. Conversely, regions that are associated with more basic perceptual processing or motor mirroring (right middle temporal cortex, right inferior occipital cortex, right inferior frontal opercular cortex) showed competitive interactions in which tuning to faces was accompanied by pruning of object responses with age.ConclusionsThe overall findings suggest that cortical maturation for face processing is regional‐specific and involves both increased tuning to faces and diminished response to nonfaces. Regions that show competitive interactions likely support a more generalized function that is co‐opted for face processing with development, whereas regions that show specialized maturation increase their tuning to faces, potentially in an activity‐dependent, experience‐driven manner.
DNA‐Nanoparticle Tinkertoys
Authors: Chandrasekaran Arun Richard 
Published: April 2016

AbstractNanoparticle superlattices can be self‐assembled by using DNA linkers, which gives control over their size, shape, and composition. Recently, such programmable atom equivalents have been tailored to respond to chemical stimuli and result in specific crystalline lattices. Moreover, the molecular recognition properties and the robustness of designed DNA nanostructures have been used in combination with metallic nanoparticles for the production of the elusive diamond superlattice.