bluuebunny/crossref_metadata_2025_split huggingface dataset:
Palladium‐Catalyzed Asymmetric 1,4‐Addition of Diarylphosphines to Nitroalkenes for the Synthesis of Chiral P,N‐Compounds
Authors: Feng Jian‐Jun , Huang Miao , Lin Zi‐Qi , Duan Wei‐Liang 
Published: November 2012

AbstractA highly stereoselective asymmetric 1,4‐addition of diarylphosphines to nitroalkenes catalyzed by a bis(phosphine) pincer‐palladium complex has been developed for the synthesis of chiral P,N compounds with good to excellent enantioselectivities (up to 94% ee) under mild conditions.
Diastereoselective Synthesis of Pyrazolines using a Bifunctional Brønsted Acidic Ionic Liquid under Solvent‐Free Conditions
Authors: Safaei Shirin , Mohammadpoor‐Baltork Iraj , Khosropour Ahmad R. , Moghadam Majid , Tangestaninejad Shahram , Mirkhani Valiollah 
Published: November 2012

AbstractAn efficient protocol for the excellent diastereoselective synthesis of pyrazolines via a three‐component reaction of aldehydes, hydrazines and dimethyl acetylenedicarboxylate (DMAD) in the presence of a bifunctional Brønsted acidic ionic liquid as a reusable catalyst under solvent‐free conditions is reported. Easy work‐up, short reaction times, high yields of the products and an environmentally benign procedure avoiding toxic organic solvents are other significant features of this method.
A Domino Desulfitative Coupling/Acylation/Hydration Process Cocatalyzed by Copper(I) and Palladium(II): Synthesis of Highly Substituted and Functionalized Pyrimidines
Authors: Quan Zheng‐Jun , Hu Wang‐Hua , Jia Xiao‐Dong , Zhang Zhang , Da Yu‐Xia , Wang Xi‐Cun 
Published: November 2012

AbstractA domino desulfitative coupling/acylation/hydration process to synthesize C‐2‐(2‐oxo‐2‐phenylethylidene)‐ and N‐3‐carbonyl‐substituted pyrimidines by unprecedented CC and CN cross‐coupling reactions is described. This methodology couples 3,4‐dihydropyrimidine‐2‐thiones and alkynes under modified Liebeskind–Srogl conditions using palladium acetate and copper(I) carboxylate. Remarkably the copper(I) carboxylates simultaneously act as desulfitative and acylation reagents in the reaction.
Solid‐Supported Rhodium(0) Nano‐/Microparticles: An Efficient Ligand‐Free Heterogeneous Catalyst for Microwave‐Assisted Suzuki–Miyaura Cross‐Coupling Reaction
Authors: Guha Nitul Ranjan , Reddy Chennayala Bal , Aggarwal Nidhi , Sharma Dharminder , Shil Arun K. , Bandna  , Das Pralay 
Published: November 2012

AbstractSolid‐supported nano‐ and microparticles of rhodium(0) (SS‐Rh) were prepared and applied as a ligand free heterogeneous catalyst for Suzuki–Miyaura cross‐coupling reaction with wide range of substrate scope. A hitherto unknown Rh‐catalyzed Suzuki cross‐coupling reaction of aldehyde and cyanohaloarenes was observed rather than the usual nucleophilic arylation.The catalyst can be removed by simple filtration and recycled upto twelve runs without any deterioration of activity.
Modular POP Ligands in Rhodium‐Mediated Asymmetric Hydrogenation: A Comparative Catalysis Study
Authors: Núñez‐Rico José L. , Etayo Pablo , Fernández‐Pérez Héctor , Vidal‐Ferran Anton 
Published: November 2012

AbstractHighly efficient and enantioselective hydrogenation reactions for α‐(acylamino)acrylates, itaconic acid derivatives and analogues, α‐substituted enol ester derivatives, and α‐arylenamides (25 substrates) catalyzed by chiral cationic rhodium complexes of a set of POP ligands have been developed. The catalytic systems derived from these POP ligands provided a straightforward access to enantiomerically enriched α‐amino acid, carboxylic acid, amine, and alcohol derivatives that are valuable chiral building blocks. Excellent efficiencies (full conversion in all cases) and extremely high enantiomeric excesses (94–99% ee) were achieved for a wide range of α‐substituted enol ester derivatives, regardless of the substitution pattern. The R‐oxy group of the ligand (methoxy or triphenylmethoxy) strongly influences the enantioselectivity and catalytic activity. Greater steric bulk around the metal centre correlated to greater (or similar) enantioselectivity, but also to slower hydrogenation. Furthermore, the hydrogenation rates observed with the four model substrates follow the same trend, independently of the R‐oxy group of the ligand: methyl 2‐acetamidoacrylate>dimethyl itaconate>1‐phenylvinyl acetate>N‐(1‐phenylvinyl)acetamide. A substrate‐to‐catalyst ratio (S/C) of up to 10,000:1 was sufficient for total hydrogenation of a model substrate of intermediate reactivity (dimethyl itaconate), and did not imply any loss in conversion or enantioselectivity.
Aminocarbonylation of (Hetero)aryl Bromides with Ammonia and Amines using a Palladium/DalPhos Catalyst System
Authors: Alsabeh Pamela G. , Stradiotto Mark , Neumann Helfried , Beller Matthias 
Published: November 2012

AbstractVariants of the DalPhos [2‐aminophenylbisadamantyl)phosphine] ligand family were examined in a palladium‐catalyzed carbonylative amination reaction using inexpensive carbon monoxide and ammonia as reagents. As a result of this survey, the Pyr‐DalPhos ligand was identified as being effective for the selective aminocarbonylation of aryl bromides with ammonia, as well as primary and secondary alkylamines. A variety of primary aromatic, heteroaromatic and N‐substituted benzamides were formed in moderate to good yields. As part of this study, a (Mor‐DalPhos)Pd‐benzoyl complex was prepared and crystallographically characterized, thereby showing the viability of the carbonyl insertion step.
A Facile Route to Benzo[a]fluorenes via a Palladium‐Catalyzed Reaction of 2‐Alkynylbromobenzene with 2‐(2‐Alkynylphenyl)malonate
Authors: Luo Yong , Pan Xiaolin , Wu Jie 
Published: November 2012

AbstractA palladium‐catalyzed reaction of 2‐alkynylbromobenzenes with 2‐(2‐alkynylphenyl)malonates gives rise to benzo[a]fluorenes in good yields. This tandem process is efficient with the formation of three bonds from easily available starting materials.
The Catalytic Potential ofCoptis japonicaNCS2 Revealed – Development and Utilisation of a Fluorescamine‐Based Assay
Authors: Pesnot Thomas , Gershater Markus C. , Ward John M. , Hailes Helen C. 
Published: November 2012

AbstractThe versatility and potential of a norcoclaurine synthase (NCS) fromCoptis japonicaNCS2 has been investigated, together with the development and application of a novel fluorescence‐based high‐throughput assay using nearly forty amines/aldehydes. The stereocontrol exerted byCjNCS2 on selected non‐natural substrates has been determined, where the tetrahydroisoquinolines (THIAs) were formed as the (1S)‐isomer in >95%ee, as observed with the natural product norcoclaurine. Docking calculations involving THIA mechanism intermediates, utilising the reportedThalictrum flavumNCS X‐ray crystallographic structure, were carried out and combined with theCjNCS2 screening results to further understand the mode of action of NCS. These findings suggested that in addition to the key active‐site residues K122 and E110, D141 is also mechanistically essential for the enzymatic transformation. The exceptional tolerance of NCS towards aldehyde substrates is furthermore supported by our proposed mechanism in which the aldehydes protrude out of the enzymatic pocket.
Experimental study of a liquid fluidization in a microfluidic channel
Authors: Zivkovic Vladimir , Biggs Mark J. , Alwahabi Zeyad T. 
Published: November 2012

SignificanceThis study reports the first ever experimental study of true micro‐fluidization: a liquid‐fluidized bed of 30.5 μm micro‐particles within a rectangular micro‐channel of 400 × 175 μm2. The failure to fluidize the micro‐particles with water demonstrated the importance of surface forces for micro‐fluidization. Use of ethanol instead leads to fluidization that is largely well described by conventional fluidization equations, although higher values of empirical constant (k and n) are obtained for Richardson‐Zaki correlation.
Possible Health Benefits From Reducing Occupational Magnetic Fields
Authors: Bowman Joseph D. , Ray Tapas K. , Park Robert M. 
Published: November 2012

AbstractBackgroundMagnetic fields (MF) from AC electricity are a Possible Human Carcinogen, based on limited epidemiologic evidence from exposures far below occupational health limits.MethodsTo help formulate government guidance on occupational MF, the cancer cases prevented and the monetary benefits accruing to society by reducing workplace exposures were determined. Life‐table methods produced Disability Adjusted Life Years, which were converted to monetary values.ResultsAdjusted for probabilities of causality, the expected increase in a worker's disability‐free life are 0.04 year (2 weeks) from a 1 microtesla (µT) MF reduction in average worklife exposure, which is equivalent to $5,100/worker/µT in year 2010 U.S. dollars (95% confidence interval $1,000–$9,000/worker/µT). Where nine electrosteel workers had 13.8 µT exposures, for example, moving them to ambient MFs would provide $600,000 in benefits to society (uncertainty interval $0–$1,000,000).ConclusionsWhen combined with the costs of controls, this analysis provides guidance for precautionary recommendations for managing occupational MF exposures. Am. J. Ind. Med. 56:791–805, 2013. Copyright © 2012 Wiley Periodicals, Inc.
“Sinus headache”: rhinogenic headache or migraine? An evidence‐based guide to diagnosis and treatment
Authors: Patel Zara M. , Kennedy David W. , Setzen Michael , Poetker David M. , DelGaudio John M. 
Published: November 2012

BackgroundPatients present to physicians across multiple disciplines with the complaint of sinus headache. This lay term is widely accepted in the media, yet has been repeatedly questioned in the medical literature, and experts in the fields of otolaryngology, neurology, and allergy have agreed that it is an overused and often incorrect diagnosis in the majority of patients. There have been review articles and consensus panels established regarding this issue, but thus far no guidelines based purely on a review of the level of evidence provided by the literature.MethodsA systematic review of the literature was performed and the Clinical Practice Guideline Manual, Conference on Guideline Standardization (COGS), and the Appraisal of Guidelines and Research Evaluation (AGREE) instrument recommendations were followed. Study inclusion criteria were: adult population >18 years old, self‐diagnosed or physician‐diagnosed “sinus headache,” clearly defined diagnostic criteria in diagnostic studies, and clearly defined primary clinical end‐point in therapeutic studies.ResultsWe identified and evaluated the literature on diagnosing and treating patients with a primary complaint of sinus headache. The literature was reviewed for both quality of research design as well as benefit and harm of the proposed interventions.ConclusionIf a thorough neurologic and otolaryngologic evaluation is performed, the majority of patients presenting with sinus headache in the absence of significant acute inflammatory findings will be diagnosed with migraine. In this situation, the appropriate treatment for the majority of patients presenting with sinus headache is migraine directed therapy. In a highly select group of patients, directed nasal surgery addressing endonasal contact points may be an option.
Die Polyamorphie von Calciumcarbonat und ihre Bedeutung für die Biomineralisation: Wie viele amorphe Calciumcarbonat‐Phasen gibt es?
Authors: Cartwright Julyan H. E. , Checa Antonio G. , Gale Julian D. , Gebauer Denis , Sainz‐Díaz C. Ignacio 
Published: November 2012

AbstractWährend die Polymorphie des Calciumcarbonats gut erforscht ist und seine kristallinen Modifikationen – Calcit, Aragonit und Vaterit – oft insbesondere im Zusammenhang mit der Biomineralisation untersucht wurden, ist das Phänomen der Polyamorphie noch nicht lange bekannt. Auch die Existenz von mehr als einer amorphen Calciumcarbonatphase ist erst vor Kurzem klar geworden. In diesem Aufsatz fassen wir zusammen, was über die Polyamorphie des Calciumcarbonats auf der einen Seite und über die Rolle des amorphen Calciumcarbonats in der Biomineralisation auf der anderen Seite bekannt ist. Unsere Betrachtungen ermöglichen uns aufzuzeigen, dass die Behandlung amorphen Calciumcarbonats im Rahmen des physikalischen Verständnisses der Polyamorphie zu neuartigen Einblicken führt, wie unterschiedliche Polymorphe überhaupt aus ihren Vorstufen entstehen können. Dies ist von großer Bedeutung für unser Verständnis der Prinzipien der Biomineralisation sowie der Mittel und Wege, wie Kristallisation in medizinischen, pharmazeutischen oder industriellen Zusammenhängen gesteuert werden kann.
Die Lys48‐verknüpfte Polyubiquitinkette als proteasomales Signal: kein Einzelkind mehr
Authors: Kravtsova‐Ivantsiv Yelena , Sommer Thomas , Ciechanover Aaron 
Published: November 2012

AbstractDie Konjugation von Ubiquitin (Ub) an Proteine ist an der Regulation vieler Prozesse beteiligt. Die Modifikation dient als in trans wirkendes Erkennungselement, wobei strangabwärts gelegene Effektoren an das modifizierte Protein binden und dessen Schicksal und/oder Funktion bestimmen. Die allgemein akzeptierte Auffassung ist, dass eine PolyUb‐Kette, die über das interne Lys48 von Ub verknüpft und an einem internen Lys‐Rest des Substrats verankert ist, das kanonische Signal für die Erkennung und den Abbau durch das Proteasom darstellt. Jüngste Studien haben jedoch gezeigt, dass das Signal weitaus vielfältiger ist und dass Ketten auf der Basis anderer interner Verknüpfungen sowie lineare oder heterologe Ketten aus Ub oder Ub‐artigen Proteinen und selbst MonoUb vom Proteasom erkannt werden. Darüber hinaus wurden auch Ketten beschrieben, die an andere als interne Lys‐Reste binden. All diese jüngsten Entdeckung stellen die gegenwärtig akzeptierte Sichtweise in Frage.
Nanotechnology‐Enabled Energy Harvesting for Self‐Powered Micro‐/Nanosystems
Authors: Wang Zhong Lin , Wu Wenzhuo 
Published: November 2012

AbstractHealth, infrastructure, and environmental monitoring as well as networking and defense technologies are only some of the potential areas of application of micro‐/nanosystems (MNSs). It is highly desirable that these MNSs operate without an external electricity source and instead draw the energy they require from the environment in which they are used. This Review covers various approaches for energy harvesting to meet the future demand for self‐powered MNSs.
Electrospinning of polymer nanofibers loaded with noncovalently functionalized graphene
Authors: Das Sriya , Wajid Ahmed S. , Bhattacharia Sanjoy K. , Wilting Michael D. , Rivero Iris V. , Green Micah J. 
Published: November 2012

AbstractPristine graphene/polyvinyl alcohol (PVA) nanofibers were prepared by electrospinning an aqueous solution of polyvinylpyrrolidone‐stabilized graphene and PVA. This is the first report of electrospun nanofibers reinforced with dispersed pristine graphene. We examine the relationship between graphene loading and critical electrospinning parameters. Microscopy indicates uniform fiber formation and excellent graphene dispersion within the fiber. Rheological data indicates that the excellent level of graphene dispersion enhances the modulus of the polymer by 205%. We also find that the graphene significantly increases the fibers' thermal stability (increase of 15°C) and crystallinity (59% increase) above the baseline. In fact, the graphene may act as nucleating points for increased crystallinity. These graphene/polymer nanofibers have the potential to serve in a variety of applications, including electrodes, conductive wires, and biomedical materials. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Synthesis and characterization of high‐performance polyimides based on 6,4′‐diamino‐2‐phenylbenzimidazole
Authors: Xia Qingming , Liu Junpeng , Dong Jie , Yin Chaoqing , Du Yuxuan , Xu Qian , Zhang Qinghua 
Published: November 2012

AbstractA new synthesis route was developed to produce the diamine monomer containing benzimidazole units, 6,4′‐diamino‐2‐phenylbenzimidazole (BIA), which was easily prepared by the reduction of 6,4′‐dinitro‐2‐phenylbenzimidazole synthesized via a reaction between 4‐nitro‐1,2‐phenylenediamine and 4‐nitrobenzoyl chloride. The composition and structure of the products were confirmed by Fourier transform infrared, NMR, and elemental analysis. A series of polyimides were prepared by the polycondensation of BIA and various dehydrates, pyromellitic dianhydride, 3,3′,4,4′‐biphenyl tetracarboxylic dianhydride, 4,4′‐oxydiphthalic anhydride, and benzophenone tetracarboxylic dianhydride via a traditional two‐step procedure. The polyimides exhibit excellent thermal stability up to 540°C and high glass transition temperature (Tg) in the range of 382–409°C. The polyimide films are tough and flexible and possess good mechanical properties of tensile strength of 222–232 MPa and modulus of 3.1–5.6 GPa without stretching. The polyimides are amorphous state in wide‐angle X‐ray diffraction patterns, whereas small‐angle X‐ray diffraction patterns show the existence of molecular aggregation. The rigid‐rod structure and intermacromolecular hydrogen bond are likely responsible for the excellent properties of the polyimides. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
The impact of flood control on the loss of wetlands in Argentina
Authors: Brandolin Pablo G. , Ávalos Miguel A. , de Angelo Carlos 
Published: November 2012

ABSTRACT

Wetlands are among the most important ecosystems on Earth, but historically they have been degraded and destroyed by humans. The south east of Córdoba province in central Argentina was covered by hundreds of wetlands in a vast matrix of grasslands and savannas. In the last few centuries, this area has been mostly transformed into agriculture, forcing wetlands to become the last refuge for remaining wildlife.
Since the mid‐1970s, a gradual increase in rainfall has enlarged the area occupied by wetlands. To reverse the situation, vast flooded regions were altered by the construction of artificial drainage channels, including important areas for conservation of biodiversity.
A non‐supervised classification of satellite images was used to assess the changes in flooded areas of south‐eastern Córdoba before the main floods (1987–1988) and after channelizations occurred (2007). Areas with high channelization (Córdoba) and non‐channelization (Santa Fe) were compared for years with the same amount of accumulated rainfall.
The pluviometric registers in both regions showed a trend of increasing annual rainfall, and this was reflected in a 65.9% increase (64 837 ha) of the flooded area in Santa Fe. Conversely, the channelized area in Córdoba suffered a loss of 12% of its ponds, corresponding to a 14.7% reduction of the flooded area (11 655 ha). A greater reduction in the flooded area (42.1%) was observed when considering only the western portion of the Córdoba site where most of the channelization occurred.
These results indicate that besides the mitigation of floods, the channelization in Córdoba favoured agriculture expansion at the expense of wetlands, thereby destroying these wildlife refuges. Wetlands are important for their biodiversity, ecosystem services, and cultural legacy. In central Argentina the channelization process still continues, so it is of the utmost importance to support conservation actions leading to sustainable management and territorial planning of this region.Copyright © 2012 John Wiley & Sons, Ltd.
Stability Analysis for Delayed Neural Networks with Discontinuous Neuron Activations
Authors: Guo Zhenyuan , Huang Lihong 
Published: November 2012

AbstractThis paper considers a class of delayed neural networks with discontinuous neuron activations. Based on the theory of differential equations with discontinuous right‐hand sides, some novel sufficient conditions are derived that ensure the existence and global exponential stability of the equilibrium point. Moreover, by adopting the concept of convergence in measure, convergence behavior for the output is discussed. The obtained results are independent of the delay parameter and can be thought of as a generalization of previous results established for delayed neural networks with Lipschtz continuous neuron activations to the discontinuous case. Finally, we give a numerical example to illustrate the effectiveness and novelty of our results by comparing our results with those in the early literature.
Anwendung des Systems Engineering auf die Arbeitsvorbereitung von Bauprojekten
Authors: Schütz Michael , Hofstadler Christian 
Published: November 2012

AbstractDieser Beitrag behandelt die Anwendung der Methodik des Systems Engineering (SE) auf die Arbeitsvorbereitung von Bauprojekten. Es soll dabei gezeigt werden, wie durch systemisches Denken und systematisches Vorgehen die in der Regel knappen Ressourcen für Arbeitsvorbereitung (Zeit und Personal) effizient genutzt werden können.Hierzu werden zunächst die Methodik des Systems Engineering vorgestellt und die Aufgaben, Ziele und Tätigkeiten der Arbeitsvorbereitung erläutert. Auf Basis dieser Grundlagen wird anschließend die Anwendung der SE‐Methodik für die Arbeitsvorbereitung auf Seiten des Auftragnehmers am Beispiel der Rohbauarbeiten beim Musiktheater Linz veranschaulicht. Abschließend werden der Nutzen der Methodik des Systems Engineering und Erkenntnisse aus der Beschäftigung mit dem Thema dargelegt.Application of the Systems Engineering method in production scheduling of building projectsThis article deals with the method of Systems Engineering (SE) in production scheduling of building projects. It shows how system thinking and systematic approach can help to use the scarce resources (time and staff) for production scheduling more efficiently.At first the method of Systems Engineering and the tasks, aims and activities of production scheduling are described. After these basics the application of the SE‐method in production scheduling is shown on the example of the structural works of the opera house of Linz. Finally the benefits of the Systems Engineering method are shown followed by the authors' conclusions.
Radarinterferometrie zum Setzungsmonitoring beim Tunnelbau
Authors: Mark Peter , Niemeier Wolfgang , Schindler Steffen , Blome Andrea , Heek Peter , Krivenko Alexander , Ziem Eberhard 
Published: November 2012

AbstractNach der Methode der “Persistent Scatterer”‐Interferometrie wird ein innovativer Ansatz zum flächenhaften Setzungsmonitoring beim Tunnelbau vorgestellt. Grundlage sind Daten aus 24 Überflügen des Radarsatelliten TerraSAR‐X des Deutschen Zentrums für Luft‐ und Raumfahrt (DLR). Die Leistungsfähigkeit dieses Verfahrens wird am Beispiel des Tunnelbauprojekts “Wehrhahn‐Linie” in Düsseldorf demonstriert. Der Beitrag beschreibt neben den wesentlichen Grundlagen zur Radarinterferometrie auch die besonderen Randbedingungen des Tunnelbauprojekts im Innenstadtbereich der Landeshauptstadt. Die Verifizierung mit punktuellen terrestrischen Messungen belegt die Genauigkeit der Methode im Millimeterbereich. Die Forschungsarbeiten sind Teil der Aktivitäten des Sonderforschungsbereichs 837 “Interaktionsmodelle im maschinellen Tunnelbau” an der Ruhr‐Universität Bochum.Radar interferometry for monitoring of settlements in tunnellingAn innovative approach employing the “Persistent Scatterer” Interferometry to monitor area‐wide settlements induced by tunnelling is presented. The method is based on data from 24 overflights of the TerraSAR‐X satellite provided by the German Aerospace Center (DLR). Exemplified on the tunnelling construction site “Wehrhahn‐Linie” located in Düsseldorf, the performance of the Radar‐Interferometry method is demonstrated. Besides the basic principles of the Radar‐Interferometry, the contribution illustrates specific boundary conditions of a tunnelling project in the intra‐urban area of the state capital city of Düsseldorf. The validation with point wise terrestrial measurements proofs that the method is accurate to a millimetre. The research project is part of the Collaborative Research Center 837 “Interaction modelling in mechanized tunnelling” at the Ruhr‐University of Bochum.