bluuebunny/crossref_metadata_2025 huggingface dataset:
Direct CH Arylations of Unactivated Arenes Catalyzed by Amido‐Functionalized Imidazolium Salts
Authors: Ghosh Debalina , Lee Jhen‐Yi , Liu Chian‐Yu , Chiang Yen‐Hsin , Lee Hon Man
Published: February 2014

The synthesis of biaryls from unactivated arenes and a broad range of aryl bromides and chlorides via the direct CH functionalization can be efficiently performed with the aid of amido‐functionalized imidazolium salts as organocatalysts. This method avoids the use of toxic transition metal catalysts and organometallic reagents.

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Quality‐relevant fault diagnosis with concurrent phase partition and analysis of relative changes for multiphase batch processes
Authors: Zhao Chunhui
Published: February 2014

Multiplicity of phases as indicated by changes of process characteristics is an inherent nature of many batch processes for both normal and fault cases. To more efficiently perform online fault diagnosis via reconstruction for multiphase batch processes, the phase nature and the relationship between normal and fault cases within each phase should be deeply addressed. This article proposes a quality‐relevant fault diagnosis strategy with concurrent phase partition and analysis of relative changes for multiphase batch processes. First, a concurrent phase partition algorithm is developed. The basic idea is to track the changes of process characteristics at normal and fault statuses jointly so that multiple sequential modeling phases are identified simultaneously for both normal and fault cases. Then, the relative changes from the normal status to each fault case are analyzed in each phase to reveal the specific fault effects more efficiently. The fault effects are decomposed in two different monitoring subspaces, principal subspace, and residual subspace, by capturing their different roles in removing out‐of‐control signals. The significant increases relative to the normal case are judged to be responsible for the concerned alarm monitoring statistics in each phase. The others are composed of general variations that are deemed to still follow normal rules and thus insignificant to remove alarm monitoring statistics. Those alarm‐responsible fault deviations are then used to develop reconstruction models which can more efficiently recover the fault‐free part for online fault diagnosis. The proposed algorithm is illustrated with a typical multiphase batch process with one normal case and three fault cases. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2048–2062, 2014
A Coordination Compound of Ge0 Stabilized by a Diiminopyridine Ligand
Authors: Chu Terry , Belding Lee , van der Est Art , Dudding Travis , Korobkov Ilia , Nikonov Georgii I.
Published: February 2014

Reduction of the cationic GeII complex [dimpyrGeCl][GeCl3] (dimpyr=2,6‐(ArN=CMe)2NC5H3, Ar=2,6‐iPr2C6H3) with potassium graphite in benzene affords an air sensitive, dark green compound of Ge0, [dimpyrGe], which is stabilized by a bis(imino)pyridine platform. This compound is the first example of a complex of a zero‐valent Group 14 element that does not contain a carbene or carbenoid ligand. This species has a singlet ground state. DFT studies revealed partial delocalization of one of the Ge lone pairs over the π*(CN) orbitals of the imines. This delocalization results in a partial multiple‐bond character between the Ge atom and imine nitrogen atoms, a fact supported by the X‐ray crystallography and IR spectroscopy data.
α‐MsO/TsO/Cl‐Ketone als oxidierte Alkin‐Äquivalente: redoxneutrale Rhodium(III)‐katalysierte C‐H‐Aktivierung zur Synthese von N‐Heterocyclen
Authors: Yu Da‐Gang , de Azambuja Francisco , Glorius Frank
Published: February 2014

α‐Halogenierte und pseudohalogenierte Ketone werden zum ersten Mal als sp3‐Kohlenstoff‐Elektrophile in der Übergangsmetall‐katalysierten C‐H‐Aktivierung sowie als oxidierte Alkin‐Äquivalente in der RhIII‐katalysierten redoxneutralen Anellierung zur Herstellung verschiedener N‐Heterocyclen eingesetzt. Die vorgestellte Methode ist effizient und skalierbar. Durch die milden Reaktionsbedindungen wird eine weite Zahl an funktionellen Gruppen toleriert.
Fourier Transform EPR Spectroscopy of Trityl Radicals for Multifunctional Assessment of Chemical Microenvironment
Authors: Bobko Andrey A. , Dhimitruka Ilirian , Zweier Jay L. , Khramtsov Valery V.
Published: February 2014

Pulse techniques in electron paramagnetic resonance (EPR) allow for a reduction in measurement times and increase in sensitivity but require the synthesis of paramagnetic probes with long relaxation times. Here it is shown that the recently synthesized phosphonated trityl radical possesses long relaxation times that are sensitive to probe the microenvironment, such as oxygenation and acidity of an aqueous solution. In principle, application of Fourier transform EPR (FT‐EPR) spectroscopy makes it possible to acquire the entire EPR spectrum of the trityl probe and assess these microenvironmental parameters within a few microseconds. The performed analysis of the FT‐EPR spectra takes into consideration oxygen‐, proton‐, buffer‐, and concentration‐induced contributions to the spectral shape, therefore enabling quantitative and discriminative assessment of pH, pO2, and concentrations of the probe and inorganic phosphate.
Frame‐Guided Assembly of Vesicles with Programmed Geometry and Dimensions
Authors: Dong Yuanchen , Sun Yawei , Wang Liying , Wang Dianming , Zhou Tao , Yang Zhongqiang , Chen Zhong , Wang Qiangbin , Fan Qinghua , Liu Dongsheng
Published: February 2014

In molecular self‐assembly molecules form organized structures or patterns. The control of the self‐assembly process is an important and challenging topic. Inspired by the cytoskeletal‐membrane protein lipid bilayer system that determines the shape of eukaryotic cells, we developed a frame‐guided assembly process as a general strategy to prepare heterovesicles with programmed geometry and dimensions. This method offers greater control over self‐assembly which may benefit the understanding of the formation mechanism as well as the functions of the cell membrane.
Nucleophile‐Dependent Regio‐ and Stereoselective Ring Opening of 1‐Azoniabicyclo[3.1.0]hexane Tosylate
Authors: Ji Mi‐Kyung , Hertsen Dietmar , Yoon Doo‐Ha , Eum Heesung , Goossens Hannelore , Waroquier Michel , Van Speybroeck Veronique , D'hooghe Matthias , De Kimpe Norbert , Ha Hyun‐Joon
Published: February 2014

1‐[(1R)‐(1‐Phenylethyl)]‐1‐azoniabicyclo[3.1.0]hexane tosylate was generated as a stable bicyclic aziridinium salt from the corresponding 2‐(3‐hydroxypropyl)aziridine upon reaction with p‐toluenesulfonyl anhydride. This bicyclic aziridinium ion was then treated with various nucleophiles including halides, azide, acetate, and cyanide in CH3CN to afford either piperidines or pyrrolidines through regio‐ and stereoselective ring opening, mediated by the characteristics of the applied nucleophile. On the basis of DFT calculations, ring‐opening reactions under thermodynamic control yield piperidines, whereas reactions under kinetic control can yield both piperidines and pyrrolidines depending on the activation energies for both pathways.
Nanowire Shish‐Kebab Structures and Molecular Orientation Control of All‐Conjugated Diblock Copolymers
Authors: Yang Hua , Wang Lei , Yu Xinhong , Zhang Jidong , Geng Yanhou , Han Yanchun
Published: February 2014

Herein we propose a facile strategy to prepare nanowires and nanowire “shish‐kebab” (NWSK) structures by controlling the crystallization behavior of all‐conjugated rod–rod diblock copolymers poly[(p‐phenylene)‐block‐(3‐hexylthiophene)]s (PPP‐b‐P3HT (BmTn)) with varying main chain lengths. Depending on the block length and ratio (i.e., PPP/P3HT, abbreviated as B/T), nanowires with low B/T ratios (copolymers with long P3HT blocks; B8T32 and B14T34) and NWSKs with high B/T ratios (copolymers with long PPP blocks; B29T9 and B39T18) were formed for PPP‐b‐P3HT all‐conjugated diblock copolymers. The formation of nanowires is governed by a strong interchain π–π stacking similar to the P3HT homopolymer, with an edge‐on orientation of the P3HT moiety, whereas NWSKs are formed as a result of the particular face‐on molecular orientation of PPP moiety. As the length of the P3HT moiety was increased (the block ratio of PPP/P3HT reduced), the NWSKs were transformed into nanowires gradually because of the decreasing density of “kebabs”. For diblock copolymers with high PPP/P3HT ratios, the transition of the molecular orientation from face‐on to edge‐on was obtained by thermal annealing.
Synthesis of New Diphosphine Ligands and their Application in Pd‐Catalyzed Alkoxycarbonylation Reactions
Authors: Pews‐Davtyan Anahit , Fang Xianjie , Jackstell Ralf , Spannenberg Anke , Baumann Wolfgang , Franke Robert , Beller Matthias
Published: February 2014

Carbocyclic and N‐heterocyclic analogues of the industrially applied ligand bis(di‐tert‐butylphosphinomethyl)benzene (1) have been synthesized in moderate to very good yields. The new ligands are based on benzene, tetralin, lutidine, pyrazine, quinoxaline, and maleimide backbones. Electronic and steric variations of the phosphorous donor sites were performed. As a benchmark reaction, the palladium‐catalyzed methoxycarbonylation of 1‐octene has been tested. Ester yields up to 64 % and high linear selectivities up to 92 % were achieved.
Base‐Line‐gestützte Verformungsmessungen an einer semi‐integralen Hohlkastenbrücke
Authors: von der Haar Christoph , Marx Steffen , Bolle Guido
Published: February 2014

Verformungsmessungen an Brückentragwerken können im Rahmen von Monitoringmaßnahmen aufschlussreiche Informationen zum Tragverhalten und zum Bauwerkszustand liefern. Geodätische Messverfahren werden für diese Durchbiegungsmessungen bevorzugt eingesetzt. Diese Verfahren ermöglichen reflektorlose und messbasisfreie Verformungsmessungen bei Abtastraten von mehreren hundert Kilohertz. Die eingesetzten Laserscanner sind in der Regel sehr teuer, wodurch diese bei Messperioden von mehreren Wochen oder Jahren und gemäßigten Genauigkeitsanforderungen an Attraktivität verlieren. Demgegenüber wird in diesem Beitrag ein relativ preiswertes Verfahren für Verformungsmessungen an Hohlkastenbrücken vorgestellt. Bei diesem Verfahren wird ein Seil oder Draht durch das Brückenbauwerk gespannt. Dieses fungiert als verformungsneutrale Messbasis (“Base‐Line”) und ermöglicht die Messwertaufnahme bzw. die Verformungsmessung mit optischen Wegaufnehmern. Dieses Messverfahren wird im Zuge von Testmessungen an einer semi‐integralen Spannbeton‐Talbrücke im Zuge der Europastraße E18 in Norwegen eingesetzt. Die Voruntersuchungen zu dem Messverfahren, durchgeführte Probemessungen an einer Hohlkastenbrücke im Stadtgebiet von Hannover und erste Ergebnisse der Testmessungen an der Talbrücke in Norwegen werden im folgenden Beitrag präsentiert.

Base‐line deformation measurements on a semi‐integral box girder bridge

Deformation measurements as part of monitoring activities can provide information about the behavior and structural condition of bridge structures. Geodetic measurement methods are preferred for these deflection measurements. These methods allow reflectorless measurements at sampling rates of several hundred kilohertz. But the used laser scanners are very expensive, by this they are losing attractiveness for measurement periods of several weeks or years and in case of moderate accuracy requirements. In contrast, a relatively inexpensive method to measure the deformations of box girder bridges is presented in this paper. In this method, a cable or wire is clamped through the bridge structure. This acts as measurement base (“base‐line") and allows deformation measurements by optical transducers. This measurement method is currently being tested as part of a monitoring program at a semi‐integral viaduct in Norway. Preliminary studies of the measurement method, conducted measurements on a box girder bridge near of Hanover and first results of test measurements at the Norwegian viaduct are presented.
Die Baakenhafenbrücke – innovative Nutzungsvielfalt und Nachhaltigkeit
Authors: Liebig Henning , Rogers Paul , Trumpf Heiko , Eyre Jim , Graubner Carl‐Alexander , Gnauert Jörg , Proost Mike , Vreven Koen
Published: February 2014

Im August 2013 wurde die Baakenhafenbrücke eröffnet und der Öffentlichkeit übergeben. Die Brücke wurde am größten Hafenbecken der neuen Hamburger HafenCity realisiert und ist die infrastrukturelle Voraussetzung für die dichte Mischung aus Wohn‐ und Freizeitnutzung, grünen Freiräumen und Arbeitsplätzen am Hafenbecken. Zugleich genügt sie den vielfältigen Nutzungsanforderungen einer modernen, nachhaltigen Stadtentwicklung, schafft Aufenthaltsräume und bindet sich harmonisch ins Umfeld ein, ohne Barrieren zu bilden.

Die Brücke kann sowohl zu Fuß als auch mit dem Fahrrad oder Auto überquert werden. Für Fußgänger ist eine besonders attraktive Lösung entwickelt worden: Zwei getrennt von der Fahrbahn geführte, geschwungene Gehwege, die der Brücke ihre charakteristische Form verleihen, bieten in ihren Wölbungen einladende Aussichtspunkte und Sitzgelegenheiten und laden zum Verweilen ein. In Bezug auf Entwicklung und Nachhaltigkeit geht von dem Brückenbauprojekt eine starke Signalwirkung aus, die weit über die Grenzen der HafenCity hinaus Einfluss nehmen wird.

The Baakenhafen bridge – Innovative, multifunctional and sustainable

Opened in August 2013 the new Baakenhafen bridge is an important piece of urban infrastructure, unlocking a key site on the HafenCity development in Hamburg. In the short term, the bridge will serve as a means of access to the Baakenhafen peninsula for the site wide construction effort. Following this wave of development, the bridge will serve its primary purpose of connecting the inhabitants and users of this new district with the city to the North. For this reason, the bridge has been designed to accommodate several modes of travel: vehicular, bicycle and pedestrian. The bridge provides generous footpaths along both edges, isolated from vehicular traffic, creating a quiet, protected environment. The rise and fall of these footpaths provide unique views in all directions. While the footpath dips towards the water it also swells in width creating a generous terraced seating area. Pedestrians are invited to sit and use the bridge as a destination as well as a connection. The impact of the bridge will be felt far beyond the extent of its immediate site as it acts as a catalyst for development and regeneration on a neighbourhood scale.
Orthotrope Platten im Stahlbrückenbau
Authors: Seiler Josef
Published: February 2014

Meilensteine der Bautechnikgeschichte:

Historischer Aufsatz von Karl Schaechterle: Neue Fahrbahnkonstruktionen für stählerne Straßenbrücken.

mit einem Kommentar von Josef Seiler
Dalsfjordbrua – 523 Meter Hängebrücke in Westnorwegen
Authors: Methner Raphael
Published: February 2014

Im Zuge des kontinuierlichen Ausbaus der norwegischen Infrastruktur erfolgt seit September 2010 die endgültige Fertigstellung der Dalsfjordverbindung an der Westküste Norwegens. Neben etwa 3, 8 Kilometer Tunnelkonstruktion ist der Bau der Dalsfjord‐Hängebrücke der bedeutungsvollste Bestandteil dieser Neubaumaßnahme. In diesem Beitrag werden die wesentlichen Betonarbeiten der Hängebrücke erläutert. Diese umfassen die Tragseilverankerungen, die Pylone sowie die Vorlandbrücken. Neben der Darstellung von Ausführungsthemen wird auf die projektspezifischen Besonderheiten eingegangen. Speziell Wetter, Strömungen und (in den Wintermonaten) wenig Sonnenlicht sowie die begrenzte Verfügbarkeit von Baustoffen und Maschinen erforderten eine detaillierte Arbeitsvorbereitung. Zudem erschwerten begrenzte Zugangsmöglichkeiten und geringe Ausweichflächen die Ausführung.

Dalsfjordbrua – 523 meters suspension bridge in western Norway

As part of the continuous expansion of the Norwegian infrastructure since September 2010, the final completion of the Dalsfjord connection has started on the west coast of Norway. In addition to approximately 3.8 kilometer of tunnel construction, building the Dalsfjord suspension bridge is the most significant part of this new connection. In this paper, the essential works of the concrete suspension bridge are explained. These include the cable anchorages, the pylons and the approach bridges. Besides the representation of construction details, in particular project‐specific features are presented. Especially weather, currents and limited sunlight (during winter months) as well as the limited availability of building materials and machinery required a detailed work preparation. In addition limited access and little alternative areas had made execution difficult.
Untersuchung einer 50 Jahre alten Spannbetonbrücke zur Genauigkeitssteigerung von Lebensdauerprognosen
Authors: Sanio David , Ahrens Mark Alexander , Mark Peter , Rode Sonja
Published: February 2014

Die Belastung bestehender Infrastruktur nimmt stetig zu. Bauwerke, insbesondere Brücken, müssen heute deutlich höheren Lasten standhalten als zum Zeitpunkt ihrer Planung und Erbauung. Insbesondere Ermüdung ist bei der Überprüfung und Nachrechnung der Bauwerke ein wesentlicher Aspekt, der in der Vergangenheit schon zu Schadensfällen geführt hat. Im Rahmen des DFG‐Forschungsprojekts “Genauigkeitsgrenzen von Lebensdauerprognosen – Experimentelle und numerische Untersuchung einer Spannbetonhochstraße unter Ermüdungsbeanspruchung” konnte an einer über 50 Jahre alten Spannbetonbrücke in Düsseldorf ein umfangreiches Bauwerksmonitoring (Komponenten: Dauermessung von Spannstahl‐ und Betondehnungen, Prüfung von Materialproben, Probebelastung, usw.) des Bauwerks durchgeführt werden. Es wird gezeigt, wie die generelle Unsicherheit, die mit Lebensdauerprognosen einhergeht, gezielt reduziert werden kann und sich dadurch die rechnerische Lebensdauer um ein Vielfaches verlängert. Unter “bestmöglichen Bedingungen” – experimentell fundierter Kenntnis relevanter Eingangsgrößen – werden die Auswirkungen diverser Parameter (Material, Verkehrslasten, Strukturmodell, usw.) herausgearbeitet und ihre Beiträge auf die Prognosequalität quantifiziert. Dazu werden zunächst das Bestandsbauwerk, dann der Ersatzneubau sowie die Situation im Heerdter Dreieck in Düsseldorf, die eine spezielle Planung erforderte, erläutert.

Increasing the accuracy of lifetime prediction by structural monitoring of a 50‐year old pre‐stressed concrete bridge

Demands on the existent infrastructure are continuously rising. Today, structures, especially bridges, have to resist significantly increased loads compared to the ones scheduled during projection and erection. In course of inspections and reassessments fatigue turned out to be of high‐relevance and even led to cases of severe damage in the past. In the DFG‐funded research project “Precision limits of lifetime prognoses – experimental and numerical investigation of an existent bridge structure subjected to fatigue” focus has been set on substantial structural monitoring of a 50‐year old pre‐stressed concrete bridge located in Düsseldorf. The measures comprise among others long‐time recording of strains (concrete and tendons), material testing and trial loading. It is shown how to capture and systematically reduce inherent uncertainty of lifetime predictions. Thereby the computed structural lifetime considerably increases. In a “best case scenario”, where comprehensive experimental input data is at hand, single parameters (e.g.: material, traffic loads, and structural model) impact on the prognosis as well as on its belonging precision has been quantified. Therefore both, the existent as well as the newly erected structure in the context of Heerdter Dreieck in Düsseldorf which demands for specific projection measures are elucidated.
Ergebnisse und Erkenntnisse zu durchgeführten Nachrechnungen von Betonbrücken in Deutschland
Authors: Fischer Oliver , Müller Andreas , Lechner Thomas , Wild Matthias , Kessner Kathrin
Published: February 2014

Zur Vereinheitlichung der Vorgehensweise bei der Nachrechnung von Straßenbrücken wurde in Deutschland im Mai 2011 die “Nachrechnungsrichtlinie” eingeführt. Im Rahmen eines von der deutschen Bundesanstalt für Straßenwesen (BASt) initiierten und von den Autoren des vorliegenden Beitrags bearbeiteten Forschungsvorhabens wurden in den vergangenen Monaten Nachrechnungsergebnisse zu insgesamt 146 Betonbrücken aus ganz Deutschland gesammelt und ausgewertet. Wesentliches Ziel des Projekts war es, Grundlagen für eine noch effizientere Nachrechnung mit aussagekräftigen Ergebnissen zu schaffen. Nachfolgend werden zunächst typische “rechnerische Defizite” benannt, welche Zusatzbetrachtungen erforderlich machen, die über die Anwendung der Sonderregelungen der Nachweisstufe 2 hinausgehen. Anschließend werden Empfehlungen zur Nachrechnung allgemein sowie zum Umgang mit rechnerischen Defiziten gegeben und es werden Vorschläge zur Aufbereitung von Nachrechnungsergebnissen vorgestellt und diskutiert.

Findings and insights concerning the results of re‐analyzed concrete bridges in Germany

In May 2011 the new guideline “Nachrechnungsrichtlinie” (standard for bridge re‐analysis and assessment) was recommended for application in order to implement a harmonized basis for the assessment of existing road bridges. Within the framework of a research project initiated and funded by the Federal Highway Research Institute (BASt) re‐analysis results of in total 146 concrete bridges were collected and evaluated. One major goal of this project was to provide a basis for a more efficient re‐analysis and an improved documentation of the results. The present paper firstly describes typical “calculatory deficits” requiring additional considerations upon completion of the so‐called re‐analysis stage 2. Subsequently, general recommendations for future re‐analyses are being provided, advices are given in terms of the handling of deficits and a proposal is made and discussed regarding presentation and documentation of re‐analysis results.
Search prefilters for mid‐infrared absorbance spectra of clear coat automotive paint smears using stacked and linear classifiers
Authors: Lavine Barry K. , Fasasi Ayuba , Mirjankar Nikhil , Sandercock Mark , Brown Steven D.
Published: February 2014

By using stacked partial least squares classifiers and genetic algorithms for feature selection and classification, it is demonstrated that search prefilters can be developed to extract investigative lead information from clear coat paint smears. The results obtained in this study also show that identifying specific wavelengths or wavelet coefficients in IR spectral data is superior to identifying informative wavelength windows when applying pattern recognition techniques to IR spectra from the paint data query (PDQ) database when differentiating paint samples by assembly plant. Search prefilters developed using specific wavelengths or wavelet coefficients outperformed search prefilters that utilized spectral regions. Clear coat paint spectra from the PDQ database may not be well suited for stacking as there are few spectral intervals that can reliably distinguish the different sample groups (i.e., assembly plants) in the data. The information contained in the IR spectra about assembly plant may not be highly compartmentalized in an interval, which also works against stacking. The similarity of the IR spectra within a plant group and the noise present in the IR spectra may also be obscuring information present in spectral intervals. Copyright © 2014 John Wiley & Sons, Ltd.
The Dark Side of Hydrogen Bonds in the Design of Optical Materials: A Charge‐Density Perspective
Authors: Nelyubina Yulia V. , Puntus Lada N. , Lyssenko Konstantin A.
Published: February 2014

A combined investigation of the structural, electronic, and optical properties of three crystalline nonaaqualanthanoid(III) triflates, [Ln(H2O)9(CF3SO3)3], has provided unambiguous experimental evidence for charge redistribution in the first coordination sphere of a lanthanide ion as a result of hydrogen bonds with outer‐sphere anions. As well as resulting in charge transfer from the noncoordinated anions to the coordinated water molecules, these hydrogen bonds give rise to a new excited state, an hydrogen‐bond‐induced charge‐transfer state, which is observed experimentally for the first time. This state was shown to be responsible for the previously unknown negative aspect of hydrogen bonds with a lanthanide‐bound water molecule: rather than increasing the luminescence efficiency of the complex, they can lead to additional quenching that is unfavorable for the task‐specific design of optical materials.
Grafting Perylenes to ZnO Nanoparticles
Authors: Schönamsgruber Jörg , Zeininger Lukas , Hirsch Andreas
Published: February 2014

A new prototype of dendritic perylenes suitable for the chemical functionalization of inorganic nanoparticles was synthesized and characterized. The bay‐functionalized perylene core of these molecular architectures was coupled to a catechol moiety, which serves as an anchor group for the functionalization of metal oxides, in particular ZnO. To increase the solubility of both the perylene and the targeted hybrid nanostructures, a Newkome‐type dendron bearing nine positive charges was introduced. This charge was also employed to stabilize the nanoparticles and further protect them from Ostwald ripening through Coulombic repulsion. ZnO quantum dots with an average diameter of 5 nm were synthesized and functionalized with the perylene derivative. Successful functionalization was clearly demonstrated by dynamic light scattering, zeta‐potential measurements, thermogravimetric analysis/MS, and UV/Vis and fluorescence spectroscopy. The generated particle dispersions were stable against agglomeration for more than eight weeks.
Reversible Binding of Solvent to Naked PbII Centers in Unusual Homoleptic Alkynyl‐Based Pt2Pb2 Clusters
Authors: Berenguer Jesús R. , Fernández Julio , Gil Belén , Lalinde Elena , Sánchez Sergio
Published: February 2014

We report a series of luminescent sandwich‐type clusters [Pt2Pb2(C≡CR)8] (R=Tol, 1; C6H4OMe‐3, 2; C6H4OMe‐4, 3) with a dynamic Pt2Pb2 metallic core, which is key to their intriguing stimuli‐responsive photophysical properties. The solvent‐free solids 1–3 display an orange emission ascribed to charge transfer from Pt–alkynyl fragments to a delocalized orbital with mixed Pt2Pb2/C≡CR nature, with a predominant lead contribution and Pb⋅⋅⋅Pb bonding character (3MLCCT/3IL). They exhibit mechanical, color, and luminescence changes that are reversible and perceivable with the naked eye, which are attributed to small inter‐ and intramolecular structural modifications induced by gentle grinding. Interestingly, 1 and 2 also exhibit remarkable and fast reversible vapochromic responses to donor solvent vapors (acetone, THFMe‐2: yellow; NCMe: green, vs. dry solids: orange). The structures of 1(acetone)2⋅2(Me2CO), 2(acetone)3, and 2(THFMe‐2)2 allow the vapochromic responses to be ascribed to the fast creation/disruption of solvate clusters [Pt2Pb2(C≡CR)8Sx] (x≥2), with concomitant electronic and geometrical modifications within the Pt2Pb2 core, which are easily accessible through a slight change in the stereochemical activity of the lone pair. The binding of one (or two) solvent molecules to Pb2+ increases the Pb⋅⋅⋅Pb separation in the metallic core, causing a destabilization of the target orbital and larger energy gaps of the transitions. All the solvates exhibit remarkable rigidochromism upon a decrease in temperature, which is also associated with the gradual increase in the transannular Pb⋅⋅⋅Pb separation, as revealed by X‐ray crystallography of 1(acetone)2 at different temperatures. Investigation of the crystal lattice of 1⋅CH2Cl2 and 3⋅2 CH2Cl2 further suggests that the lack of vapor stimuli response of complex 3 could be attributed to the presence of competitive additional secondary intermolecular Pb⋅⋅⋅O(OMe) contacts, which give rise to a more compact network built up from extended chains of clusters.
Synthesis of 2,5‐Diaryl‐Substituted Thiophenes as Helical Mimetics: Towards the Modulation of Islet Amyloid Polypeptide (IAPP) Amyloid Fibril Formation and Cytotoxicity
Authors: Hassanpour Avid , De Carufel Carole Anne , Bourgault Steve , Forgione Pat
Published: February 2014

A range of 2,5‐diarylated thiophenes were synthesised as small molecule mimetics of the α‐helix to modulate the amyloidogenesis and cytotoxic effect of islet amyloid polypeptide (IAPP). 3‐Substituted thiophene‐2‐carboxylic acids were used as key intermediates and functionalised by palladium decarboxylative cross‐coupling and direct CH activation successively with overall yields ranging from 23 to 95 %. The effect of the ligands on IAPP amyloid fibril formation was evaluated with the thioflavin T (ThT) fluorescence‐based assay. Furthermore, the capacity of these compounds to inhibit the cytotoxic effect of IAPP was assessed using β‐pancreatic cells.
Catalytic Asymmetric Formal [3+3] Cycloaddition of an Azomethine Ylide with 3‐Indolylmethanol: Enantioselective Construction of a Six‐Membered Piperidine Framework
Authors: Shi Feng , Zhu Ren‐Yi , Dai Wei , Wang Cong‐Shuai , Tu Shu‐Jiang
Published: February 2014

A catalytic asymmetric formal [3+3] cycloaddition of 3‐indolylmethanol and an in situ‐generated azomethine ylide has been established to construct a chiral six‐membered piperidine framework with two stereogenic centers. This approach not only represents the first enantioselective cycloaddition of isatin‐derived 3‐indolylmethanol, but also has realized an unusual enantioselective formal [3+3] cycloaddition of azomethine ylide rather than its common [3+2] cycloadditions. Besides, this protocol combines the merits of a multicomponent reaction and organocatalysis, which efficiently assembles a variety of isatin‐derived 3‐indolylmethanols, aldehydes, and amino esters into structurally diverse spiro[indoline‐3,4′‐pyridoindoles] with one all‐carbon quaternary stereogenic center in high yields and excellent enantioselectivities (up to 93 % yield, >99 % enantiomeric excess (ee)). Although the diastereoselectivity of the reaction is generally moderate, most of the diastereomers can be separated by using column chromatography followed by preparative TLC.
Organocatalytic One‐Pot Synthesis of Highly Substituted Pyridazines from Morita–Baylis–Hillman Carbonates and Diazo Compounds
Authors: Mao Haibin , Lin Aijun , Tang Zhongkai , Hu Hongwen , Zhu Chengjian , Cheng Yixiang
Published: February 2014

A biologically inspired organocatalytic one‐pot synthesis of highly functionalized pyridazines, which are ubiquitous structural units in a number of biologically active compounds, has been developed by starting from readily available diazo compounds and Morita–Baylis–Hillman (MBH) carbonates. Under mild reaction conditions, this synthetic route tolerated significant substrate variation to deliver a broad range of substituted products, including CF3‐substituted pyridazines derivatives. Moreover, the introduction of trifluoromethyl groups into the ring of pyridazine could be completed conveniently from 2,2,2‐trifluorodiazoethane.
Highly Enantioselective Extraction of Underivatized Amino Acids by the Uryl‐Pendant Hydroxyphenyl‐Binol Ketone
Authors: Huang Haofei , Chen Qian , Choi Misun , Nandhakumar Raju , Su Zhishan , Ham Sihyun , Kim Kwan Mook
Published: February 2014

The hydroxyphenyl chiral ketone, (S)‐3, reacts with D‐amino acids bearing hydrophobic side chains exclusively over the L‐amino acids in a two‐phase liquid–liquid extraction, and thus acts as a highly stereoselective extractant. Calculations for the energy‐minimized structures for the imine diastereomers and the comparison of the selectivities with other phenyl ketones, (S)‐4 and (S)‐5, demonstrate that the hydrogen bond between the carboxylate group and the phenolic hydroxyl group contributes to the remarkable enantioselectivities. The multiple hydrogen bonds present in the imine of (S)‐3 reinforce the rigidity, and results in the difference between the stabilities of the imine diastereomers. The imine could be hydrolyzed in methanolic HCl solution, and the extraction of the evaporated residues revived the organic layer of (S)‐3, which could enter into a new extractive cycle and leaves the D‐amino acid with enantiomeric excess (ee) values of over 97 % in the aqueous layer.
Inorganic Double‐Helix Nanotoroid of Simple LithiumPhosphorus Species
Authors: Ivanov Alexander S. , Boldyrev Alexander I. , Frenking Gernot
Published: February 2014

A theoretical study of Li90P90, which possesses a circular double‐helix structure that resembles the Watson–Crick DNA structure, is reported. This is a new bonding motif in inorganic chemistry. The calculations show that the molecule might become synthesized and that it could be a model for other inorganic species which possess a double‐helix structure.
Stable Mixed‐Valent Radicals from Platinum(II) Complexes of a Bis(dioxolene) Ligand
Authors: Loughrey Jonathan J. , Sproules Stephen , McInnes Eric J. L. , Hardie Michaele J. , Halcrow Malcolm A.
Published: February 2014

Three diplatinum(II) complexes [{PtL}2(μ‐thea)] (H4thea=2,3,6,7‐tetrahydroxy‐9,10‐dimethyl‐9,10‐dihydro‐9,10‐ethanoanthracene) have been prepared, with diphosphine or bipyridyl “L” co‐ligands. One‐electron oxidation of these complexes gave radical cations containing a mixed‐valent [thea]3− ligand with discrete catecholate and semiquinonate centers separated by quaternary methylene spacers. The electronic character of these radicals is near the Robin–Day class II/III border determined by UV/Vis/NIR and EPR spectroscopies. Crystal‐structure determinations and a DFT calculation imply that oxidation of the thea4− ligand may lead to an increased through‐space interaction between the dioxolene π systems.
Saturated Excitation Microscopy with Optimized Excitation Modulation
Authors: Yonemaru Yasuo , Yamanaka Masahito , Smith Nicholas I. , Kawata Satoshi , Fujita Katsumasa
Published: February 2014

Saturated excitation (SAX) microscopy utilizes the nonlinear relation between fluorescence emission and excitation under saturated excitation to improve the spatial resolution of confocal microscopy. In this study, we theoretically and experimentally investigate the saturation of fluorescence excitation under modulated excitation to optimize the excitation conditions for SAX microscopy. Calculation of the relationships between fluorescence and excitation intensity with different modulation frequencies reveals that the lifetime of the triplet state of the fluorescent probe strongly affects the strength of the demodulated fluorescence signals. We also find that photobleaching shows little dependence on the modulation frequency. These investigations allow us to determine the optimum excitation conditions, that is, the conditions providing sufficient fluorescence saturation without strong photobleaching. For a sample stained with ATTO Rho6G phalloidin, we estimate the optimal excitation conditions, which are produced with 50 kHz excitation modulation and a 50 μsec pixel dwell time, and successfully perform three‐dimensional imaging with sub‐diffraction resolution.
Organohelium Compounds: Structures, Stabilities and Chemical Bonding Analyses
Authors: Fourré Isabelle , Alvarez Elsa , Chaquin Patrick
Published: February 2014

This paper deals with the possibility of forming short and relatively strong carbon–helium bonds in small typical organic molecules through substitution of one or several H atoms by He+. A structural and energetics study (based on high‐level calculations) of this unusual bonding, as well as a topological characterization of the resulting cations, is undertaken. Stable species generally requires substitution of about half of the hydrogen atoms for formation. Under these conditions, the number of such species appears to be potentially unlimited. “True” CHe bonds exhibit equilibrium distances ranging from 1.327 (C2H2He22+) to 1.129 Å (He2CO2+). The energies of neutral He releasing range from approximately 5 kcal mol−1[He2CO2+, (Z)‐C2H2He22+] to 25 kcal mol−1(C2HHe33+), but remain most frequently around 10 kcal mol−1. However, most of He+‐substituted hydrocarbons are metastable with respect to CC cleavage, except derivatives of ethene. Atoms in molecules (AIM) and electron localization function (ELF) topological descriptors classify the CHe bond as a weak charge‐shift interaction [S. Shaik, D. Danovich, B. Silvi, D. L. Lauvergnat, P. C. Hiberty,Chem. Eur. J. 2005, 11, 6358–6371] in agreement with a recent publication by Rzepa [S. H. Rzepa,Nat. Chem. 2010, 2, 390–393]. He2CO2+is the only investigated compound that presents a CHe bonding ELF basin, which indicates a non‐negligible covalent contribution to the bond. Other modifications in the electronic structure, such as the breaking of the triple bond in ethyne derivatives or the loss of aromaticity in C6H3He33+, are also nicely revealed by the ELF topology.
A workflow task scheduling algorithm based on the resources' fuzzy clustering in cloud computing environment
Authors: Guo Fengyu , Yu Long , Tian Shengwei , Yu Jiong
Published: February 2014

Cloud computing is the key and frontier field of the current domestic and international computer technology, workflow task scheduling plays an important part of cloud computing, which is a policy that maps tasks to appropriate resources to execute. Effective task scheduling is essential for obtaining high performance in cloud environment. In this paper, we present a workflow task scheduling algorithm based on the resources' fuzzy clustering named FCBWTS. The major objective of scheduling is to minimize makespan of the precedence constrained applications, which can be modeled as a directed acyclic graph. In FCBWTS, the resource characteristics of cloud computing are considered, a group of characteristics, which describe the synthetic performance of processing units in the resource system, are defined in this paper. With these characteristics and the execution time influence of the ready task in the critical path, processing unit network is pretreated by fuzzy clustering method in order to realize the reasonable partition of processor network. Therefore, it largely reduces the cost in deciding which processor to execute the current task. Comparison on performance evaluation using both the case data in the recent literature and randomly generated directed acyclic graphs shows that this algorithm has outperformed the HEFT, DLS algorithms both in makespan and scheduling time consumed. Copyright © 2014 John Wiley & Sons, Ltd.
A novel noncooperative game competing model using generalized simple additive weighting method to perform network selection in heterogeneous wireless networks
Authors: Salih Yass K. , Hang See Ong , Ibrahim Rabha W. , Yussof Salman , Iqbal Azlan
Published: February 2014

Network selection mechanisms have a significant role in guaranteeing the QoS for users in a heterogeneous wireless networks environment. These mechanisms allow the selection of an optimal wireless network to satisfy the needs of users. Users are provided with the opportunity to select from multiple connectivity opportunities available all over various wireless networks. Furthermore, the network operators themselves can execute active selection strategies that facilitate proper decision making, in which user preferences are considered. This study proposes a new noncooperative competing game‐theoretic model and strategy space based on user preference. This model can solve network selection problems and capture the inter‐linkages of decisions taken by various networks. A generalized simple additive weighting method is incorporated into the framework of noncooperative game theory. In addition, the utility function is employed to assess the usefulness of the system. Simulation results and analysis illustrate the efficacy of the suggested model in attaining optimum network utility for heterogeneous wireless networks while optimizing user satisfaction. Copyright © 2014 John Wiley & Sons, Ltd.
Button‐based method for the prevention of near field communication relay attacks
Authors: Kang Sukin , Kim Jonguk , Hong Manpyo
Published: February 2014

In this study, we developed a novel method for preventing relay attacks over near field communication (NFC) using a simple interface. NFC provides standardized short‐range contactless communication using one of the radio frequency identification communication channels. NFC‐enabled mobile devices can exchange information in close proximity (within 4 cm). In particular, modern mobile phones have adopted NFC technology because of its promising functionalities, for example, mobile payments, Bluetooth pairing, and electronic keys. The distance limitation of NFC communication offers security advantages against passive or active attackers, but it is still vulnerable to relay attacks. During a relay attack, adversaries relay messages between two legitimate participants without any attempt at message modification. There is no requirement for knowledge of a cryptographic key or to share secrets with victims, therefore encrypting messages is not a solution that prevents relay attacks. We propose a new method for relay attack prevention, which uses a simple interface with only one button. In our scheme, the elapsed time of button pressing is used for verification. Our experimental results obtained using the proposed scheme demonstrated the accuracy of our method for verifying human users and the difficulties experienced by human attackers. Copyright © 2014 John Wiley & Sons, Ltd.
A novel grouped multilevel dynamic space–time trellis coding scheme
Authors: Jain Dharmvir , Sharma Sanjay
Published: February 2014

Grouped multilevel space–time trellis codes (GMLSTTCs) utilize multilevel coding, antenna grouping and STTCs for simultaneously providing coding gain, diversity improvement and increased spectral efficiency. The performance of GMLSTTCs is limited because of using predefined STTCs as component codes in multilevel coding. GMLSTTCs assume perfect channel state information (CSI) at the receiver only and do not consider the CSI at the transmitter. It has been shown that when perfect or partial CSI is available at the transmitter, the performance and capacity of a space–time coded system can be further improved. In this paper, we present new codes, designed by combining GMLSTTCs and the CSI information at the transmitter, henceforth referred to as grouped multilevel dynamic space–time trellis codes (GMLDSTTCs). A code set having different sets of generator sequences is selected that matches best with the current channel profile. The selected code set is used for generating DSTTCs. DSTTCs are used as component codes in GMLSTTCs instead of predefined STTCs to generate GMLDSTTCs. Analysis and simulation results show that GMLDSTTCs outperform GMLSTTCs. Copyright © 2014 John Wiley & Sons, Ltd.
Restrictive mitral annuloplasty with or without surgical ventricular reconstruction in ischaemic cardiomyopathy: impacts on neurohormonal activation, reverse left ventricular remodelling and survival
Authors: Kainuma Satoshi , Taniguchi Kazuhiro , Toda Koichi , Funatsu Toshihiro , Miyagawa Shigeru , Kondoh Haruhiko , Masai Takafumi , Otake Shigeaki , Yoshikawa Yasushi , Nishi Hiroyuki , Sakaguchi Taichi , Ueno Takayoshi , Kuratani Toru , Daimon Takashi , Sawa Yoshiki
Published: February 2014

Aims

In the STICH trial, adding surgical ventricular reconstruction (SVR) to coronary artery bypass grafting (CABG) reduced LV end‐systolic volume index (LVESVI) by 19%, as compared with 6% with CABG alone, providing no survival or functional benefits. Herein, we compared the efficacy of restrictive mitral annuloplasty (RMA) alone with that of RMA combined with SVR in patients with functional mitral regurgitation (MR).

Methods and results

One hundred and six patients with ischaemic cardiomyopathy underwent RMA with (n = 52) or without SVR (n = 54) for functional MR. Pre‐ and post‐operative (1 month) left ventriculography and longitudinal measurements of plasma BNP were performed. Pre‐operatively, patients who underwent RMA plus SVR had a larger LVESVI (126 ± 26 vs. 100 ± 24 mL/m2, P < 0.0001). After surgery, RMA plus SVR reduced LVESVI more than RMA alone (43% vs. 22%, P <0.0001), yielding a nearly identical post‐operative LVESVI (71 ± 17 vs. 78 ± 26 mL/m2). Survival rate was not different between the groups (4‐year survival, 62% vs. 62%, P = 0.99), though among patients with pre‐operative LVESVI ranging from 105 to 150 mL/m2, that was higher in the RMA plus SVR group (73% vs. 40%, P = 0.046), accompanied by a larger percentage reduction in plasma BNP from baseline to the latest follow‐up examination (63 ± 34% vs. 34 ± 46%, P = 0.012). After propensity score adjustment, patients with LVESVI ranging from 105 to 150 mL/m2 who underwent RMA alone showed a greater association with mortality (hazard ratio 7.5, 95% confidence interval 2.1–27, P = 0.010), as compared with those with LVESVI <105 mL/m2 who underwent RMA alone.

Conclusions

RMA plus SVR reduced LVESVI to a greater degree than RMA alone, neutralizing anticipated worse prognosis. Selected patients with functional MR and advanced LV remodelling may benefit by adding SVR to RMA.
Connective tissue growth factor and cardiac diastolic dysfunction: human data from the Taiwan Diastolic Heart Failure Registry and molecular basis by cellular and animal models
Authors: Wu Cho‐Kai , Wang Yi‐Chih , Lee Jen‐Kuang , Chang Sheng‐Nan , Su Mao‐Yuan , Yeh Huei‐Ming , Su Ming‐Jai , Chen Jin‐Jer , Chiang Fu‐Tien , Hwang Juey‐Jen , Lin Jiunn‐Lee , Tsai Chia‐Ti
Published: February 2014

Aims

Connective tissue growth factor (CTGF) is an emerging marker for tissue fibrosis. We investigated the association between CTGF and cardiac diastolic function using cellular and animal models and clinical human data.

Methods and results

A total of 125 patients with a diagnosis of diastolic heart failure (DHF) were recruited from 1283 patients of the Taiwan Diastolic Heart Failure Registry. The severity of DHF was determined by tissue Doppler imaging (E/e′). Cardiac magnetic resonance imaging (CMRI) was used to evaluate myocardial fibrosis in some of the patients (n = 25). Stretch of cardiomyocytes on a flexible membrane base serves as a cellular phenotype of cardiac diastolic dysfunction (DD). A canine model of DD was induced by aortic banding. A significant correlation was found between plasma CTGF and E/e′ in DHF patients. The severity of cardiac fibrosis evaluated by CMRI also correlated with CTGF. In the cell model, stretch increased secretion of CTGF from cardiomyocytes. In the canine model, myocardial tissue CTGF expression and fibrosis significantly increased after 2 weeks of aortic banding. Notably, the expression of CTGF paralleled the severity of LV DD (r = 0.40, P < 0.001 for E/e') and haemodynamic changes (r = 0.80, P < 0.001). After adjusting for confounding factors, CTGF levels still correlated with diastolic parameters in both human and canine models (human plasma CTGF, P < 0.001; canine tissue CTGF, P = 0.04).

Conclusion

Plasma CTGF level correlated with the severity of DD and tissue fibrosis in DHF patients. The mechanism may be through myocardial stretch. Our study indicated that CTGF may serve as an early marker for DHF.