bluuebunny/crossref_metadata_2025_split huggingface dataset:
Copper‐Catalysed Conjugate Addition of Grignard Reagents to 2‐Methylcyclopentenone and Sequential Enolate Alkylation
Authors: Calvo Beatriz C. , Madduri Ashoka V. R. , Harutyunyan Syuzanna R. , Minnaard Adriaan J. 
Published: May 2014

AbstractThe copper/Rev‐JosiPhos‐catalysed asymmetric conjugate addition of Grignard reagents to 2‐methylcyclopentenone (1) provides 2,3‐disubstituted cyclopentanones in high yields and enantioselectivities, and good diastereoselectivities. Reaction of thein situformed enolate with various alkylating reagents in the presence of 1,3‐dimethyltetrahydropyrimidine‐2(1H)‐one (DMPU) affords the corresponding products in a one‐pot reaction. This procedure creates two vicinal stereocentres, one of them quaternary.magnified image
Enantioselective Construction of the Biologically Significant Dibenzo[1,4]diazepine Scaffold via Organocatalytic Asymmetric Three‐Component Reactions
Authors: Wang Yang , Tu Man‐Su , Shi Feng , Tu Shu‐Jiang 
Published: May 2014

AbstractThe first catalytic asymmetric construction of the biologically important dibenzo[1,4]diazepine scaffold has been established via SPINOL‐derived chiral phosphoric acid‐catalyzed three‐component reactions of aldehydes, 1,2‐phenylenediamines and cyclohexane‐1,3‐diones, which afforded structurally complex and diverse dibenzo[1,4]diazepines in high yields and good enantioselectivities (up to 98% yield, 92:8 er). This transformation also represents the first catalytic asymmetric version of this three‐component reaction and provides an easy access to structurally rigid seven‐membered chiral heterocycles.magnified image
Synthesis of Quinazolinones from Alcohols via Laccase‐Mediated Tandem Oxidation
Authors: Heidary Marjan , Khoobi Mehdi , Ghasemi Sabrieh , Habibi Zohreh , Faramarzi Mohammad Ali 
Published: May 2014

AbstractThis paper describes the synthesis of quinazolinones via a tandem reaction using the laccase‐mediator system under mild conditions. The procedure involved the laccase‐catalyzed oxidation of alcohols to the corresponding aldehydes, followed by cyclocondensation with isatoic anhydride and a number of amines to afford 2,3‐dihydroquinazolin‐4(1H)‐ones, which were further oxidized to quinazolinones in useful yields. The use of an enzyme as the catalyst, O2 as an environmentally friendly oxidant, and a citrate buffer as the green solvent represents a novel and efficient approach for the one‐pot synthesis of quinazolinones.magnified image
Synthesis of Biaryls through Aromatic CH Bond Activation: A Review of Recent Developments
Authors: Hussain Ibrar , Singh Tripti 
Published: May 2014

AbstractThis review describes recent progress made in the rapidly developing field of CH bond activation, in particular for syntheses of biaryls. The catalysts presented here provide convenient strategies for the direct arylation of arenes, via single or double CH bond activation, leading to inter‐, and intramolecular carbon‐carbon bond formation. The literature from mid‐2009 to December 2013 has been discussed.magnified image
When and for whom are relative age effects important? evidence from a simple test of cardiorespiratory fitness
Authors: Veldhuizen Scott , Wade Terrance J. , Cairney John , Hay John A. , Faught Brent E. 
Published: May 2014

ABSTRACTObjectivesWhen individuals of different ages are combined into a single group and an ability that varies with age is measured, younger individuals are disadvantaged. This phenomenon is known as a relative age effect (RAE) and has been shown to be widespread in sport and education.MethodsIn this article, we examine RAEs in a large group of children tested repeatedly on the 20‐m shuttle run, a common test of cardiorespiratory fitness. Following up on an earlier study that measured change with age, we add a growth curve model for change in variance, which makes it possible to derive RAEs for individuals of different ages and ability levels.ResultsResults show that a 1‐year difference in age is associated with a change in performance of about 0.2 standard deviations. For 1‐year age groups, this gives rise to ranking errors of 4 percentile ranks or less. We also show, however, that these relatively small ranking errors are capable of producing large age differences within groups identified as exceptional. Depending on the level of ability required for selection, children born in the first quarter of the year can be expected to outnumber those born in the last by 1.5 times, 2 times, or more. This finding is consistent with previously reported variation in RAEs at different performance levels.ConclusionsResults imply that RAEs are likely to be of relatively minor concern when people are graded or ranked but can produce substantial inequities and misclassifications when people with extremely high or extremely low ability levels undergo selection. Am. J. Hum. Biol. 26:476–480, 2014. © 2014 Wiley Periodicals, Inc.
Laceration injuries and infections among workers in the poultry processing and pork meatpacking industries
Authors: Kyeremateng‐Amoah Emmanuel , Nowell Jackie , Lutty Aurora , Lees Peter S.J. , Silbergeld Ellen K. 
Published: May 2014

BackgroundWorkers in poultry processing and pork meatpacking have high rates of acute injuries and chronic disease among. The presence of zoonotic pathogens in these workplaces may interact with injury.MethodsWe investigated incidence of worker injuries, lacerations, and infections reported by 10 companies from 2004 to 2009 and calculated annual incidence rates by industry and company along with temporal trends and job‐related risk factors.ResultsAverage annual mean total injury rates were 6.4 per 100 workers (poultry) and 13.2 per 100 workers (pork). Average annual mean rates for lacerations were 1.8 per 100 workers (poultry) and 1.9 per 100 (pork). Sharp tools and animal products were most frequently reported as sources for lacerations. Animal products were most frequently reported as sources of infected lacerations.ConclusionsThe results indicate that these industries continue to have high injury rates. The results also suggest that zoonotic pathogens may be preventable health and safety risks. Am. J. Ind. Med. 57:669–682, 2014. © 2014 Wiley Periodicals, Inc.
Copper‐Based Metal–Organic Frameworks as Reusable Heterogeneous Catalysts for the One‐Pot Syntheses of Imidazo[1,2‐a]pyridines
Authors: Puthiaraj Pillaiyar , Ramu Andy , Pitchumani Kasi 
Published: May 2014

AbstractA copper terephthalate metal–organic framework (Cu(BDC) MOF, BDC=1,4‐benzenedicarboxylate) is used as a highly efficient heterogeneous catalyst for the one‐pot, atom‐economical synthesis of imidazo[1,2‐a]pyridines that proceeds through the three‐component coupling of aldehydes, aminopyridines, and nitromethane. This heterocyclic synthesis, which uses MOFs for the first time, involves an intermolecular aza‐Michael addition with a subsequent intramolecular cyclization and uses air as an environmentally benign oxidant. This heterogeneous Cu(BDC) MOF can be reused without the loss of its activity. Its catalytic efficiency was also highlighted by comparing it with other catalytic systems that have been used for the syntheses of imidazo[1,2‐a]pyridines. This procedure not only eliminates the use of environmentally hazardous reagents but also involves mild reaction conditions.
Tumor necrosis factor reduces the amplitude of rat cortical spreading depression in vivo
Authors: Richter Frank , Lütz Wibke , Eitner Annett , Leuchtweis Johannes , Lehmenkühler Alfred , Schaible Hans‐Georg 
Published: May 2014

ObjectiveBrain damage and ischemia often trigger cortical spreading depression (CSD), which aggravates brain damage. The proinflammatory cytokine tumor necrosis factor (TNF) is significantly upregulated during brain damage, but it is unknown whether TNF influences spreading depression in cerebral cortex in vivo. This question is important because TNF not only furthers inflammatory reactions but might also be neuroprotective. Here we tested the hypothesis that TNF affects CSD, and we explored the direction in which CSD is modified by TNF.MethodsCSD, elicited by pressure microinjection of KCl, was recorded in anesthetized rats and mice. TNF was administered locally into a trough, providing local TNF treatment of a cortical area. For further analysis, antibodies to TNF receptor (TNFR) 1 or 2 were applied, or CSD was monitored in TNFR1 and TNFR2 knockout mice. γ‐Aminobutyric acid (GABA)A receptors were blocked by bicuculline. Immunohistochemistry localized the cortical expression of TNFR1 and TNFR2.ResultsLocal application of TNF to the cortex reduced dose‐dependently the amplitude of CSD. This effect was prevented by blockade or knockout of TNFR2 but not by blockade or knockout of TNFR1. TNFR2 was localized at cortical neurons including parvalbumin‐positive inhibitory interneurons, and blockade of GABAA receptors by bicuculline prevented the reduction of CSD amplitudes by TNF.InterpretationWe identified a functional link between TNF and CSD. TNF activates TNFR2 in cortical inhibitory interneurons. The resulting release of GABA reduces CSD amplitudes. In this manner, TNF might be neuroprotective in pathological conditions. Ann Neurol 2014;76:43–53
Acidic‐pH‐Activatable Fluorescence Probes for Visualizing Exocytosis Dynamics
Authors: Asanuma Daisuke , Takaoka Yousuke , Namiki Shigeyuki , Takikawa Kenji , Kamiya Mako , Nagano Tetsuo , Urano Yasuteru , Hirose Kenzo 
Published: May 2014

AbstractLive imaging of exocytosis dynamics is crucial for a precise spatiotemporal understanding of secretion phenomena, but current approaches have serious limitations. We designed and synthesized small‐molecular fluorescent probes that were chemically optimized for sensing acidic intravesicular pH values, and established that they can be used to sensitively and reliably visualize vesicular dynamics following stimulation. This straightforward technique for the visualization of exocytosis as well as endocytosis/reacidification processes with high spatiotemporal precision is expected to be a powerful tool for investigating dynamic cellular phenomena involving changes in the pH value.
Photocaging of Carboxylic Acids: A Modular Approach
Authors: Szymański Wiktor , Velema Willem A. , Feringa Ben L. 
Published: May 2014

AbstractPhotocaged compounds are important tools for studying and regulating multiple processes, including biological functions. Reported herein is the use of the Passerini multicomponent reaction for modular preparation of photocaged carboxylic acids. The reaction is compatible with several functionalities and proceeds smoothly both in water and dichloromethane. The choice of aldehyde determines the wavelength used for deprotection and enables formation of orthogonally protected products. The isocyanide component can be used for introduction of reactive tags and photosensitizers, as well as for immobilization on a solid support.
Trihapto‐Koordination eines Borirens an ein einzelnes Metallatom: ein heterocyclisches Analogon des η3‐Cyclopropenylliganden
Authors: Braunschweig Holger , Dewhurst Rian D. , Radacki Krzysztof , Tate Christopher W. , Vargas Alfredo 
Published: May 2014

AbstractEin erstes Beispiel für einen einkernigen Komplex mit einem η3‐koordinierten Borirenliganden wurde durch photolytischen Transfer eines Arylborylens auf Diphenylacetylen und Abspaltung von drei CO‐Gruppen aus dem Edukt erhalten. Der η3‐Borirenkomplex enthält ein Chrom(0)‐Zentrum, das zusätzlich η6‐artig an eine Phenylgruppe koordiniert. Der Komplex wird mit 15 % Ausbeute isoliert, und außerdem fällt das Metall‐freie Boriren in 62 % Ausbeute an. Die Bindung des Chromzentrums an den Borirenring wurde mit DFT‐Methoden untersucht.
[CpRu]‐Catalyzed Carbene Insertions into Epoxides: 1,4‐Dioxene Synthesis through SN1‐Like Chemistry with Retention of Configuration
Authors: Achard Thierry , Tortoreto Cecilia , Poblador‐Bahamonde Amalia I. , Guénée Laure , Bürgi Thomas , Lacour Jérôme 
Published: May 2014

AbstractRather than lead to the usual deoxygenation pathway, metal carbenes derived from α‐diazo‐β‐ketoesters undergo three‐atom insertions into epoxides using a combination of 1,10‐phenanthroline and [CpRu(CH3CN)3][BArF] as the catalyst. Original 1,4‐dioxene motifs are obtained as single regio‐ and stereoisomers. A perfect syn stereochemistry (retention, e.r. up to 97:3) is observed for the ring opening, which behaves as an SN1‐like transformation.
Highly Selective Allylborations of Aldehydes Using α,α‐Disubstituted Allylic Pinacol Boronic Esters
Authors: Hesse Matthew J. , Essafi Stéphanie , Watson Charlotte G. , Harvey Jeremy N. , Hirst David , Willis Christine L. , Aggarwal Varinder K. 
Published: May 2014

Abstractα,α‐Disubstituted allylic pinacol boronic esters undergo highly selective allylborations of aldehydes to give tetrasubstituted homoallylic alcohols with exceptional levels of anti‐Z‐selectivity (>20:1). The scope of the reaction includes both acyclic and cyclic allylic boronic esters which lead to acyclic and exocyclic tetrasubstituted homoallylic alcohols. The use of β‐borylated allylic boronic esters gave fully substituted alkenes bearing a boronic ester which underwent further cross‐coupling enabling a highly modular and stereoselective approach to the synthesis of diaryl tetrasubstituted alkenes. Computational analysis revealed the origin of the remarkable selectivity observed.
The Origin of the Selectivity and Activity of Ruthenium‐Cluster Catalysts for Fuel‐Cell Feed‐Gas Purification: A Gas‐Phase Approach
Authors: Lang Sandra M. , Bernhardt Thorsten M. , Krstić Marjan , Bonačić‐Koutecký Vlasta 
Published: May 2014

AbstractGas‐phase ruthenium clusters Run+ (n=2–6) are employed as model systems to discover the origin of the outstanding performance of supported sub‐nanometer ruthenium particles in the catalytic CO methanation reaction with relevance to the hydrogen feed‐gas purification for advanced fuel‐cell applications. Using ion‐trap mass spectrometry in conjunction with first‐principles density functional theory calculations three fundamental properties of these clusters are identified which determine the selectivity and catalytic activity: high reactivity toward CO in contrast to inertness in the reaction with CO2; promotion of cooperatively enhanced H2 coadsorption and dissociation on pre‐formed ruthenium carbonyl clusters, that is, no CO poisoning occurs; and the presence of Ru‐atom sites with a low number of metal–metal bonds, which are particularly active for H2 coadsorption and activation. Furthermore, comprehensive theoretical investigations provide mechanistic insight into the CO methanation reaction and discover a reaction route involving the formation of a formyl‐type intermediate.
Programmable and Highly Resolved In Vitro Detection of 5‐Methylcytosine by TALEs
Authors: Kubik Grzegorz , Schmidt Moritz J. , Penner Johanna E. , Summerer Daniel 
Published: May 2014

AbstractGene expression is extensively regulated by specific patterns of genomic 5‐methylcytosine (mC), but the ability to directly detect this modification at user‐defined genomic loci is limited. One reason is the lack of molecules that discriminate between mC and cytosine (C) and at the same time provide inherent, programmable sequence‐selectivity. Programmable transcription‐activator‐like effectors (TALEs) have been observed to exhibit mC‐sensitivity in vivo, but to only a limited extent in vitro. We report an mC‐detection assay based on TALE control of DNA replication that displays unexpectedly strong mC‐discrimination ability in vitro. The status and level of mC modification at single positions in oligonucleotides can be determined unambiguously by this assay, independently of the overall target sequence. Moreover, discrimination is reliably observed for positions bound by N‐terminal and central regions of TALEs. This indicates the wide scope and robustness of the approach for highly resolved mC detection and enabled the detection of a single mC in a large, eukaryotic genome.
Assessing the Brønsted Basicity of Diaminoboryl Anions: Reactivity toward Methylated Benzenes and Dihydrogen
Authors: Dettenrieder Nicole , Aramaki Yoshitaka , Wolf Benjamin M. , Maichle‐Mössmer Cäcilia , Zhao Xiaoxi , Yamashita Makoto , Nozaki Kyoko , Anwander Reiner 
Published: May 2014

AbstractTreatment of toluene or p‐xylene with diaminoboryllithium results in consecutive reactions, involving boryl‐anion‐mediated deprotonation at the benzylic position followed by nucleophilic substitution at the boron center, producing benzylborane species and LiH. Diaminoboryllithium also cleaves H2 heterolytically affording diaminohydroborane and LiH, while the reaction of lithium diaminoboryl(bromo)cuprate with H2 takes place accompanied by reduction of CuI to give diaminohydroborane, LiH, and Cu0.
Towards High‐Performance Lewis Acid Organocatalysis
Authors: Ratjen Lars , van Gemmeren Manuel , Pesciaioli Fabio , List Benjamin 
Published: May 2014

AbstractThe combination of Lewis acid organocatalysis and internal hydrogen‐bond assistance was used to develop a new type of highly active disulfonimide catalyst. The increased Lewis acidity was documented by activity comparisons as well as theoretical investigations. Finally, the potential of the hydrogen‐bond‐assisted disulfonimide catalyst was demonstrated by its application in an enantioselective transformation.
Linear‐nonlinear dichotomy of the rheological response of particle‐filled polymers
Authors: Randall Amy M. , Robertson Christopher G. 
Published: May 2014

ABSTRACTNovel nanoparticles, polymer‐particle coupling agents, and functionalized polymers are being developed to enhance the performance of particle‐reinforced polymer systems such as advanced rubber compounds for automobile tires. Understanding the complex rheological behavior of rubber is critical to providing insights into both processability and end‐use properties. One unique aspect of the rheology of filled elastomers is that the incorporation of particles introduces a hysteretic softening (Payne effect) at small dynamic strains. This study demonstrates that this nonlinear viscoelastic behavior needs to be considered when attempting to correlate steady shear response (Mooney viscosity) to oscillatory shear measurements from test equipment such as the Rubber Process Analyzer (RPA). While a wide array of unfilled gum elastomers show good correlation between Mooney viscosity and dynamic torque from the RPA at all of the strain amplitudes used, rubber compounds containing silica and carbon black particles only exhibit good agreement between the two measures of processability when the oscillatory strain amplitude is high enough to sufficiently break up the filler network. Other features of the filler network and its influence on nonlinear rheology are considered in this investigation, including the effects of polymer–filler interactions on filler flocculation and the use of Fourier transform rheometry to illustrate the “linear‐nonlinear dichotomy” of the Payne effect. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40818.
Polyaniline with high crystallinity degree: Synthesis, structure, and electrochemical properties
Authors: Du Xianfeng , Xu Youlong , Xiong Lilong , Bai Yang , Zhu Jianbo , Mao Shengchun 
Published: May 2014

ABSTRACTPolyaniline (PANI) with high crystallinity degree was facilely synthesized on the surface of stainless steel net by galvanostatic method. The effect of polymerization current density on the characteristics of morphology and structure had been investigated by field emission scanning electron microscopy (FE‐SEM), Fourier transforms infrared (FTIR), X‐ray photoelectron spectroscopy (XPS), and X‐ray diffraction (XRD). FE‐SEM observations disclosed that PANI was deposited as nanofibers and their diameters decreased with the polymerization current density. FTIR studies revealed that degree of oxidation increased in order PANI‐2 < PANI‐6 < PANI‐10. XPS measurements displayed that PANI polymerized at 6 mA cm−2 (PANI‐6) exhibited much higher doping level of 77.8%, which favored the conductivity. XRD analysis discovered that the obtained PANI showed high crystallinity degree in which PANI‐6 possessed highest crystallinity degree (Xcr) up to 67%. Electrochemical performances of PANI as electrode materials were studied via cyclic voltammetry. The results presented that PANI‐6 possessed greater discharge capacity and better reversibility. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40827.
Effect of reinforcement of sustainable β‐CaSiO3 nanoparticles in bio‐based epoxy resin system
Authors: Tiimob Boniface J. , Rangari Vijaya K. , Jeelani Shaik 
Published: May 2014

ABSTRACTThe β‐CaSiO3 nanoparticles (NPs) were prepared using calcium carbonate from egg shells and silica as precursors. These NPs were incorporated (1–4 wt %) into bio‐based epoxy resin to fabricate nanocomposites. Thermal and mechanical tests were carried out on these composites. The results of dynamic mechanical analysis showed significant improvement in the storage modulus of 1 and 2 wt % composites. The thermomechanical analysis data revealed ∼19 and 20% of reduction in coefficient of thermal expansion for 1 wt % of CaSiO3 before and after glass transition as compared to the neat epoxy system. Thermogravimetric analysis results also showed delayed thermal degradation of the composites by significant amounts (17–35°C) for 5% of decomposition, a proportional increase in residues corresponding to the loading concentrations. The flexure tests showed significant improvements in strength (17–36%), modulus (5–33%), and toughness for 1–4 wt % of reinforcement of β‐CaSiO3 NPs. Theoretical calculations of the reinforcement effect on the flexure modulus of the composites agree well with the experimental values. The scanning electron micrograph of the fractured surfaces revealed better interfacial interactions in the composites and enhancements in crack path deflections over the neat specimen. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40867.
Influence of the interfacial adhesion on the stringiness of crosslinked polyacrylic pressure‐sensitive adhesives
Authors: Ito Keiko , Shitajima Kohei , Karyu Nozomi , Fujii Syuji , Nakamura Yoshinobu , Urahama Yoshiaki 
Published: May 2014

ABSTRACTThe stringiness of crosslinked polyacrylic pressure‐sensitive adhesives (PSA) was observed during 90° peeling under a constant peel rate with various adherends in order to clarify the influence of interfacial adhesion on the stringiness behavior. The crosslinked random copolymer of butyl acrylate with 5 wt % acrylic acid was used as a representative PSA. Poly(methyl methacrylate) (PMMA), polycarbonate (PC), poly(vinyl chloride) (PVC), fused quartz plates and some surface‐modified poly(ethylene terephthalate) films were used as adherends. The films were pasted on a glass plate using a cyanoacrylate adhesive. The 180° peel strength was higher in the order of PVC >> PMMA ≈ PC > other adherends. All observed stringiness was sawtooth‐shaped, but the stringiness width and length were longer in the same order. The number of sub‐branches formed at the tips of the strings was much more for the PVC, PMMA and PC adherends. Frames formed at the front end of the strings in the case of PVC adherend. Sufficient interfacial adhesion generates large internal deformation of the PSA layer. Internal deformation occurred preferentially over peeling as a result of front frame formation. The string length and the peel load required for the constant peel rate have good correlation with the peel strength. The estimation of generated inner stress in the fibrils of the strings was possible by analysis using the string length for various adherends and the stress–strain curve of pure PSA. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40869.