bluuebunny/crossref_metadata_2025_split huggingface dataset:
Frequency and voltage dependence of dielectric properties, complex electric modulus, and electrical conductivity in Au/7% graphene doped‐PVA/n‐Si (MPS) structures
Authors: Altındal Yerişkin Seçkin , Balbaşı Muzaffer , Tataroğlu Adem 
Published: May 2016

ABSTRACTIn order to increase the capacitance of Au/n‐Si (MS) structure, 7% graphene doped PVA was coated on n‐Si as an interfacial layer. The measured data of capacitance (C) and conductance (G/ω) of Au/7% graphene doped‐PVA/n‐Si (MPS) structure was utilized for the calculation of real and imaginary parts of complex permittivity (ε* = ε′ − jε″), loss tangent (tanδ), complex electric modulus (M* = M′ + jM″), and electrical conductivity (σ). The admittance measurements (C and G/ω) were carried out in the frequency range of 0.5 kHz to 1 MHz at room temperature. Frequency dependence of the dielectric constant (ε′), dielectric loss (ε″) and tanδ shows a dispersive behavior at low frequencies. This behavior was explained by Maxwell–Wagner relaxation. Due to the dipolar and the interfacial polarizations, as well as the surface states (Nss) and the interfacial PVA layer, the parameters exhibited a strong dependence on frequency and applied bias voltage. The σ versus log(f) plot exhibited both low and high frequency dispersion phenomena such that at low frequencies σ value corresponding to the dc conductivity (σdc), but at high frequencies it corresponds to the ac conductivity (σac). M′ and M″, both, have low values in the low frequency region. However, an increase is observed with the increasing frequency due to the short‐range mobility of charge carriers. As a result, the change in dielectric parameters and electric modulus with frequency is the result of relaxation phenomena and surface states. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43827.
PLA/Pluronic® nanoparticles as potential oral delivery systems: Preparation, colloidal and chemical stability, and loading capacity
Authors: Palacio Juliana , Agudelo Natalia A. , Lopez Betty L. 
Published: May 2016

ABSTRACTMixed nanoparticles of PLA and Pluronic® were developed to overcome the low chemical and colloidal stability in the gastrointestinal track for PLA nanoparticles. The aim of present study was to improve the stability of coating the PLA nanoparticle surface with hydrophilic polymers, such as poly(ethylene oxide). The Pluronic® covered PLA nanoparticles were prepared through nanoprecipitation method. The method was optimized in terms of addition order, type, and concentration of Pluronic® and stirring velocity to obtain particles with sizes around 100 nm. The ζ potential measurements and thermal analysis confirmed the formation of PEO layers around the nanoparticles. Dynamic Light Scattering studies of mixed PLA/Pluronic® nanoparticles showed colloidal and chemical stability during storage and in simulated gastrointestinal fluids, suggesting this system as an alternative for the delivery of therapeutics via oral administration. The nanoparticles ability of encapsulating hydrophobic drugs was evaluated using Nile Red as a probe molecule. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43828.
Fault Detection Based On Online Probability Density Function Estimation
Authors: Ghaniee Zarch Majid , Alipouri Yousef , Poshtan Javad 
Published: May 2016

AbstractThis study presents a new fault detection scheme based on the probability density function (PDF) of system output. Unlike the classical fault detection and diagnosis methods, in the proposed method, distribution of the system output is estimated online. To achieve this goal, an algorithm is introduced to estimate PDF online using fuzzy logic. Furthermore, convergence of this algorithm is investigated. Then, a residual is constructed that can show the existence of a fault in the system. The main advantages of the proposed method are robustness against measurement noise, even though it does not need the exact model and measured data of inputs and states. Simulation results show that this scheme can detect abrupt faults very well.
Bemessungsereignisse für vorübergehende Bau‐ bzw. Revisionsphasen bei Hochwasserschutzbauwerken
Authors: Niehüser Sebastian , Jensen Jürgen , Bender Jens 
Published: May 2016

AbstractIn Deutschland werden Hochwasserschutzbauwerke i. d. R. so bemessen, dass sie einem Hochwasserereignis mit einer definierten Eintrittswahrscheinlichkeit standhalten können. Bei der Festlegung der anzusetzenden Eintrittswahrscheinlichkeit sollten die im Versagensfall zu erwartenden Schäden in dem zu schützenden Bereich berücksichtigt werden. Die erwartete Nutzungsdauer für z. B. Deiche beträgt dabei i. d. R. zwischen 50 und 100 Jahren. Die geotechnischen Nachweise sind entsprechend europäischer Regelungen und nationalen Ergänzungen für eine Referenzperiode von 50 Jahren durchzuführen. Hinweise zum Hochwasserschutz in Bau‐ und Revisionszeiten werden nur beispielhaft erwähnt, wie anfallende Baumaßnahmen nur in Jahreszeiten auszuführen, in denen die Wahrscheinlichkeit großer Hochwasserereignisse geringer ist. Dabei stellt sich jedoch die Frage nach einem Wiederkehrintervall, das hier angesetzt werden sollte. Letztlich geht es um die Abschätzung der Wahrscheinlichkeit, dass ein bestimmtes Ereignis an einem Standort in einem Zeitraum der Bau‐ und Revisionsphase eintritt.In diesem Beitrag wird exemplarisch ein Ansatz unter Anwendung der Poisson‐Verteilung vorgestellt, der den Zusammenhang zwischen der Eintrittswahrscheinlichkeit von Bemessungsereignissen unter Einbeziehung der benötigten Bau‐ und Revisionszeiten sowie der Schutzbedürftigkeit des Hinterlands berücksichtigt.Design events for temporary construction or revision periods of flood protection measuresFlood protections measures in Germany are designed in a way that they can withstand a flooding event with a defined frequency of occurrence. The evaluation of the return period of the design event should include potential damages in the hinterland or the protected area, respectively. However, flood protection structures are usually designed for an estimated operation time between 50 and 100 years. The geotechnical evidence has to be carried out in accordance with European regulations and their national supplements for a reference period of 50 years. But, the realization of the flood protection in terms of temporary construction or revision phases is only mentioned exemplarily as to perform them in seasons in which the likelihood of large floods is less. Here, the question arises about the return period to account for. Hence, the focus is on estimating the probability that a particular event occurs at a specific site during the construction or revision period.In this paper, we introduce an approach based on the Poisson distribution taking into account the relation between the frequency of occurrence of design events and the construction or revision period as well as the vulnerability of the area to be protected.
Tragwerksplanung und Rohbauausführung des neuen Henninger Turm
Authors: Gerritzen Dominique , Sack Steffen , Bachmann Hubert , Mukherjee Dilip , Tang Xiaofeng 
Published: May 2016

AbstractIm vorliegenden Beitrag wird über besondere Fragestellungen und Lösungen bei der Tragwerksplanung und der Rohbauausführung des neuen Henninger Turm in Frankfurt berichtet. Bei dem 140 m hohen Henninger Turm handelt es sich um ein schwingungsanfälliges Bauwerk, welches besondere Anforderungen an die Planung der aussteifenden Bauteile, die Gründung und die Modellierung des Tragwerks stellt. Zunächst wird dargestellt, wie der anspruchsvolle Entwurf der Architekten (MSW – Meixner Schlüter Wendt) bei einer maximalen Raumausnutzung möglichst wirtschaftlich tragwerksplanerisch umgesetzt und die Kombination der unterschiedlichen Gebäudearten von Turm und Sockel fugenlos realisiert wurde. Weiterhin werden besondere Lösungen bei der Bauausführung aufgezeigt, mit denen es gelang, den Rohbau des gesamten Henninger Turm in etwas mehr als 1 ½ Jahren fertig zu stellen.Structural design and construction of the new Henninger TurmThe following paper covers special issues and solutions on the structural design and construction of the new Henninger Turm in Frankfurt. The 140 m tall high‐rise building susceptible to structure oscillations demanded special efforts in the design of the bracing structural elements, the foundation and the structural modelling. The first part of the paper focuses on how the ambitious architetural design by MSW – Meixner Schlüter Wendt was adopted in a maximum space and cost‐efficient structural design in which the contrary building types, high‐rise building and base structure, were combined jointless. The second part shows special construction solutions due to which the complete shell construction could be completed in somewhat more than 1 ½ years.
Proton Affinities of Cationic Carbone Adducts [AC(PPh3)2]+(A=Halogen, Hydrogen, Methyl) and Unusual Electronic Structures of the Cations and Dications [AC(H)(PPh3)2]2+
Authors: Petz Wolfgang , Kuzu Istemi , Frenking Gernot , Andrada Diego M. , Neumüller Bernhard , Fritz Maximilian , Münzer Jörn E. 
Published: May 2016

AbstractThis work reports the syntheses and the first crystal structures of the cationic carbone adducts [FC(PPh3)2]+and [BrC(PPh3)2]+and the protonated dication [FC(H)(PPh3)2]2+, which are derived from the carbone C(PPh3)2. Quantum chemical calculations and bonding analyses were carried out for the series of cations [AC(PPh3)2]+and dications [AC(H)(PPh3)2]2+, where A=H, Me, F, Cl, Br, I. The bonding analysis suggests that the cations are best described as phosphane complexes L→(CA)+←L (L=PPh3), which are related to the neutral borylene adducts L→(BA)←L (L=cyclic carbene; A=H, aryl) that were recently isolated. The carbone adducts [AC(PPh3)2]+possess a π electron lone pair at carbon and they can easily be protonated to the dications [AC(H)(PPh3)2]2+. The calculations of the dications indicate that the molecules are best represented as complexes L→(CHA)2+←L (L=PPh3) where a carbene dication is stabilized by the ligands. The central carbon atom in the cations and even in the dications carries a negative partial charge, which is larger than the negative charge at fluorine. There is also the peculiar situation in which the carbon–fluorine bonds in [FC(PPh3)2]+and [FC(H)(PPh3)2]2+exhibit the expected polarity with the negative end at fluorine, but the carbon atom has a larger negative charge than fluorine. Given the similarity of carbodiphosphorane C(PPh3)2and carbodicarbene C(NHC)2, we expect that analogous compounds [AC(NHC)2]+and [AC(H)(NHC)2]2+with similar features as [AC(PPh3)2]+and [AC(H)(PPh3)2]2+can be isolated.
Zinc Porphyrin Metal‐Center Exchange at the Solid–Liquid Interface
Authors: Franke Matthias , Marchini Florencia , Jux Norbert , Steinrück Hans‐Peter , Lytken Ole , Williams Federico J. 
Published: May 2016

AbstractDemetalation of zinc 5,10,15,20‐tetraphenylporphyrin (ZnTPP) under acidic conditions and ion exchange with Cu2+ ions at neutral pH are both rapid reactions in the liquid medium. However, for ZnTPP monolayers adsorbed on a Au(111) surface exposed to aqueous solution, we find that, although ion exchange takes place rapidly as expected, demetalation does not occur, even at pH values as low as 0. Based on this, we conclude that metal center exchange on the surface does not proceed through a free‐base porphyrin as an intermediate. Furthermore, once formed, CuTPP is stable on the surface and the reverse exchange from CuTPP to ZnTPP in the presence of Zn2+ ions could not be achieved. The preference for copper is so strong that even an attempt to exchange adsorbed ZnTPP with Ni2+ ions in the presence of traces of Cu2+ yielded CuTPP rather than NiTPP.
Differential Recognition of Anions with Selectivity towards F− by a Calix[6]arene–Thiourea Conjugate Investigated by Spectroscopy, Microscopy, and Computational Modeling by DFT
Authors: Nehra Anita , Bandaru Sateesh , Yarramala Deepthi S. , Rao Chebrolu Pulla 
Published: May 2016

AbstractAnion recognition studies were performed with triazole‐appended thiourea conjugates of calix[6]arene (i.e., compound 6L) by absorption and 1H NMR spectroscopy by using nineteen different anions. The composition of the species of recognition was derived from ESI mass spectrometry. The absorption spectra of compound 6L showed a new band at λ=455 nm in the presence of F− due to a charge transfer from the anion to the thiourea moiety and the absorbance increases almost linearly in the concentration range 5 to 200 μm. This is associated with a strong visual color change of the solution. Other anions, such as H2PO4− and HSO4−, exhibit a redshift of the λ=345 nm band and the spectral changes are associated with the formation of an isosbestic point at λ=343 nm. 1H NMR studies further confirm the binding of F− efficiently to the thiourea group among the halides by shifting the thiourea proton signals downfield followed by their disappearance after the addition of more than one equivalent of F−. The other anions also showed interactions with compound 6L, however, their binding strength follows the order F−>CO32−>H2PO4−≈CH3COO−>HSO4−. The NMR spectral changes clearly revealed the anion‐binding region of the arms in case of all these anions. The anion binding to compound 6L indeed stabilizes a flattened‐cone conformation as deduced based on the calix‐aromatic proton signals and was further confirmed by VT 1H NMR experiments. The stabilization of the flattened‐cone conformation was further augmented by the interaction of the butyl moiety of the nBu4N+ counterion. The structural features of the anion‐bound species were demonstrated by DFT computations and the resultant structures carried the features that were predicted based on the 1H NMR spectroscopic measurements. In addition, SEM images showed a marigold flower‐type morphology for compound 6L and this has been transformed into a chain‐like structure of connected spherical particles in the presence of F−. The anion‐induced microstructural features are reflective of the binding strength, size, and shape of the anions. The binding strengths of the anions by compound 6L were further compared with that of compound 4L, a calix[4]arene analogue of compound 6L, in order to address the role of the number of arms built on the calixarene platform based on absorption spectroscopy, 1H NMR spectroscopy, and DFT computations and it was found that compound 6L is a better receptor for F−, which extends its interactions from all the three arms.
Combined Chemical Activation and Fenton Degradation to Convert Waste Polyethylene into High‐Value Fine Chemicals
Authors: Chow Cheuk‐Fai , Wong Wing‐Leung , Ho Keith Yat‐Fung , Chan Chung‐Sum , Gong Cheng‐Bin 
Published: May 2016

AbstractPlastic waste is a valuable organic resource. However, proper technologies to recover usable materials from plastic are still very rare. Although the conversion/cracking/degradation of certain plastics into chemicals has drawn much attention, effective and selective cracking of the major waste plastic polyethylene is extremely difficult, with degradation of C−C/C−H bonds identified as the bottleneck. Pyrolysis, for example, is a nonselective degradation method used to crack plastics, but it requires a very high energy input. To solve the current plastic pollution crisis, more effective technologies are needed for converting plastic waste into useful substances that can be fed into the energy cycle or used to produce fine chemicals for industry. In this study, we demonstrate a new and effective chemical approach by using the Fenton reaction to convert polyethylene plastic waste into carboxylic acids under ambient conditions. Understanding the fundamentals of this new chemical process provides a possible protocol to solve global plastic‐waste problems.
Solid‐Phase Synthesis and Characterization of N‐Terminally Elongated Aβ−3–x‐Peptides
Authors: Beyer Isaak , Rezaei‐Ghaleh Nasrollah , Klafki Hans‐Wolfgang , Jahn Olaf , Haußmann Ute , Wiltfang Jens , Zweckstetter Markus , Knölker Hans‐Joachim 
Published: May 2016

AbstractIn addition to the prototypic amyloid‐β (Aβ) peptides Aβ1–40 and Aβ1–42, several Aβ variants differing in their amino and carboxy termini have been described. Synthetic availability of an Aβ variant is often the key to study its role under physiological or pathological conditions. Herein, we report a protocol for the efficient solid‐phase peptide synthesis of the N‐terminally elongated Aβ‐peptides Aβ−3–38, Aβ−3–40, and Aβ−3–42. Biophysical characterization by NMR spectroscopy, CD spectroscopy, an aggregation assay, and electron microscopy revealed that all three peptides were prone to aggregation into amyloid fibrils. Immunoprecipitation, followed by mass spectrometry, indicated that Aβ−3–38 and Aβ−3–40 are generated by transfected cells even in the presence of a tripartite β‐site amyloid precursor protein cleaving enzyme 1 (BACE1) inhibitor. The elongated Aβ peptides starting at Val(−3) can be separated from N‐terminally‐truncated Aβ forms by high‐resolution isoelectric‐focusing techniques, despite virtually identical isoelectric points. The synthetic Aβ variants and the methods presented here are providing tools to advance our understanding of the potential roles of N‐terminally elongated Aβ variants in Alzheimer's disease.
Regioselective Alkylative Carboxylation of Allenamides with Carbon Dioxide and Dialkylzinc Reagents Catalyzed by an N‐Heterocyclic Carbene–Copper Complex
Authors: Gholap Sandeep Suryabhan , Takimoto Masanori , Hou Zhaomin 
Published: May 2016

AbstractThe alkylative carboxylation of allenamide catalyzed by an N‐heterocyclic carbene (NHC)–copper(I) complex [(IPr)CuCl] with CO2 and dialkylzinc reagents was investigated. The reaction of allenamides with dialkylzinc reagents (1.5 equiv) and CO2 (1 atm.) proceeded smoothly in the presence of a catalytic quantity of [(IPr)CuCl] to afford (Z)‐α,β‐dehydro‐β‐amino acid esters in good yields. The reaction is regioselective, with the alkyl group introduced onto the less hindered γ‐carbon, and the carboxyl group introduced onto the β‐carbon atom of the allenamides. The first step of the reaction was alkylative zincation of the allenamides to give an alkenylzinc intermediate followed by nucleophilic addition to CO2. A variety of cyclic and acyclic allenamides were found to be applicable to this transformation. Dialkylzinc reagents bearing β‐hydrogen atoms, such as Et2Zn or Bu2Zn, also gave the corresponding alkylative carboxylation products without β‐hydride elimination. The present methodology provides an easy route to alkyl‐substituted α,β‐dehydro‐β‐amino acid ester derivatives under mild reaction conditions with high regio‐ and stereoselectivtiy.
Chiral Phosphate in Rhodium‐Catalyzed Asymmetric [2+2+2] Cycloaddition: Ligand, Counterion, or Both?
Authors: Barbazanges Marion , Caytan Elsa , Lesage Denis , Aubert Corinne , Fensterbank Louis , Gandon Vincent , Ollivier Cyril 
Published: May 2016

AbstractInvestigations based on NMR spectroscopy, mass spectrometry, and DFT calculations shed light on the metallic species generated in the rhodium‐catalyzed asymmetric [2+2+2] cycloaddition reaction between diynes and isocyanates with the chiral phosphate TRIP. The catalytic mixture comprising [{Rh(cod)Cl}2], 1,4‐diphenylphosphinobutane (dppb), and Ag(S)‐TRIP actually gives rise to two species, both having an effect on the stereoselectivity. One is a rhodium(I) complex in which TRIP is a weakly coordinating counterion, whereas the other is a bimetallic Rh/Ag complex in which TRIP is a strongly coordinating X‐type ligand.
A Snapshot of the Properties of Single Nanoparticles at the Moment of a Collision
Authors: Huang Xinjian , Deng Haiqiang , Liu Cheng , Jiang Jing , Zeng Qiang , Wang Lishi 
Published: May 2016

AbstractDirect electrochemical characterization of freely moving nanoparticles (NPs) at the individual particle level is challenging. A method is presented that can achieve this goal based on the collision between a NP and an ultramicroelectrode (UME). By applying a sinusoidal potential to the UME and monitoring the current response in the frequency domain, a sudden change in the phase angle indicates the arrival of a NP at the UME. The response induced by the collision can be isolated and used to explore the properties of the NP. This method, analogous to a high‐speed camera, can obtain a snapshot of the properties of the single NP at the moment of a collision. The proposed method was employed to investigate the properties of both the hard catalytic Pt NP and soft electroactive emulsion droplets, and many new insights were revealed thereafter. The method also has the potential to be applied in many other fields, where the interested signals appear as discrete events.
Iridium‐Catalyzed Intramolecular Methoxy C−H Addition to Carbon–Carbon Triple Bonds: Direct Synthesis of 3‐Substituted Benzofurans from o‐Methoxyphenylalkynes
Authors: Torigoe Takeru , Ohmura Toshimichi , Suginome Michinori 
Published: May 2016

AbstractCatalytic hydroalkylation of an alkyne with methyl ether was accomplished. Intramolecular addition of the C−H bond of a methoxy group in 1‐methoxy‐2‐(arylethynyl)benzenes across a carbon–carbon triple bond took place efficiently either in toluene at 110 °C or in p‐xylene at 135 °C in the presence of an iridium catalyst. The initial 5‐exo cyclization products underwent double‐bond migration during the reaction to give 3‐(arylmethyl)benzofurans in high yields.
ChemInform Abstract: Anomalous Diffusion of Tin in GaAs.
Authors: ERKAYA H. H. , ROEDEL R. J. , LAREAU R. , WILLIAMS P. , LEAVITT J. , VON NEIDA A. 
Published: May 2016

AbstractDurch die Sn‐Diffusion in ein p‐GaAs‐ Substrat, die in einem "leaky tube"‐Diffusionssystem durchgeführt wird, soll versucht werden, mit einer Niedrigtemp.‐Verfahrenstechnik n ‐ p‐Übergänge zu erzeugen.
ChemInform Abstract: Mössbauer‐Study of the Thermal Transformations of Kaolin Caminau at Temperatures from 383K to 1465 K.
Authors: MOYA T. , FOURNES L. , HAGENMULLER P. , KOLDITZ L. , BLUMENTHAL G. , WEGNER G. 
Published: May 2016

AbstractDas im Kaolin in unterschiedlichen Bindungsformen vorliegende Eisen wird mittels Mössbauer‐Spektroskopie charakterisiert und damit die Vorgänge bei den thermischen Umwandlungen bis 1465 K verfolgt.
ChemInform Abstract: Indium Oxide, Oxygen Photoanode of High Quantum Efficiency.
Authors: SCHUMACHER L. C. , MAMICHE‐AFARA S. , DIGNAM M. J. 
Published: May 2016

AbstractDurch Oxidation (O2, 30 min, 350°C) dünner In‐Metallfilme werden In2O3‐Filme von ca. 1000Å Dicke hergestellt und auf ihre photoelektrochemischen Eigenschaften untersucht.
ChemInform Abstract: Studies in the Flexibility of Macrocycle Ligands. Calculation of Macrocycle Cavity Size by Force‐field Methods.
Authors: DREW M. G. B. , HOLLIS S. , YATES P. C. 
Published: May 2016

AbstractDer Co‐Komplex kristallisiert in der RG P212121 mit Z=4 und ist oktaedrisch koordiniert.
ChemInform Abstract: N‐Aryl‐N′‐acetylureido‐O‐alkylxanthates and Bis‐[N‐aryl‐N′‐acetylureido]‐O‐polymethylene Bisxanthates.
Authors: JOSHI P. C. JUN. , KARNATAK K. B. , SAH M. M. , PANT A. K. 
Published: May 2016

AbstractDie Chloressigsäureureide (I) werden mit Ka1iummethyl‐ oder ‐ethylxanthogenat zu den Acetylureidoxanthogenaten (II) und mit den Dikaliumdixanthogenaten (III) zu (IV) umgesetzt.
ChemInform Abstract: Olefin Synthesis via the Lithium Derivatives of the N,N,N′,N′‐Tetramethyldiamides of Arylmethanephosphonic Acids.
Authors: PETROVA J. , MOMCHILOVA S. , KIRILOV M. 
Published: May 2016

AbstractDie Lithium‐Derivate der Phosphonsäureamide (I) reagieren mit den Aldehyden (II) bei tiefer Temperatur mit hoher Selektivität zu den erythro‐Addukten (III), die bei der Thermolyse die Z‐Olefine (IV) ergeben.
ChemInform Abstract: Stereoselective Insertion of the Isopropenyl Functionality.
Authors: SILVESTRI M. G. , BEDNARSKI P. J. , KHO E. 
Published: May 2016

AbstractDer aus trans‐9‐Methyl‐ 2‐decalon (I) mit (II) gut zugängliche Aldehyd (III) wird ins p‐Tosylhydrazon (IV) übergeführt.