bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of alternating voltage treatment on corrosion resistance of AZ91D magnesium alloy
Authors: Liu X. , Zhang T. , Shao Y. , Meng G. , Wang F. 
Published: February 2011

AbstractAZ91D magnesium alloy was treated by the alternating voltage (AV) treatment technique. The optimal AV‐treatment parameters of the alloy were determined by orthogonal experiments. Polarization curve, electrochemical impedance spectroscopy (EIS), and scanning electrochemical microscopy (SECM) were used to understand the effect of AV‐treatment on the corrosion resistance of the alloy. AFM, contact angle, and XPS were employed to investigate further the influence of AV‐treatment on the properties of the surface film formed on the alloy after AV‐treatment. The results showed that a uniform and stable film was formed and the corrosion resistance of AZ91D magnesium alloy was significantly improved after AV‐treatment. This was caused by the noticeable change of the chemical structure and semi‐conducting properties of the surface film after AV‐treatment.
Synthesis of Blockcopolymers P3HT‐b‐PS Using a Combination of Grignard‐Metathesis and Nitroxide‐Mediated Radical Polymerization
Authors: Britze Antje , Möllmann Vera , Grundmeier Guido , Luftmann Heinrich , Kuckling Dirk 
Published: February 2011

AbstractThe synthesis of π‐conjugated NMRP‐macroinitiators using GRIGNARD‐metathesis polymerization in combination with azide/alkyne‐“click” chemistry has been investigated. Alkoxyamine‐functionalized poly(3‐hexylthiophene)s (P3HTs) have been used for block copolymer preparations in presence of styrene. Molecular weight and molecular weight distribution of the polymers have been determined in SEC‐measurements, while end‐group determination was performed with MALDI‐ToF‐MS. The molecular weight of the P3HT macroinitiators was influenced by the amount of Ni‐catalyst during the GRIM reaction. Those macroinitiators have been used to prepare block copolymers in subsequent nitroxide‐mediated radical polymerization (NMRP). Thin‐layer‐morphologies of the block copolymers were investigated using tapping‐mode AFM. Short and disordered rods were observed, as well as continuous and parallel fibrils.
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Microstructure and incubation processes in composite liquid crystalline material (5CB) filled with multi walled carbon nanotubes
Authors: Lisetski L. N. , Minenko S. S. , Ponevchinsky V. V. , Soskin M. S. , Goncharuk A. I. , Lebovka N. I. 
Published: February 2011

AbstractThis work reports a study on microstructure, electrical conductivity and phase transitions of 5CB(4‐pentyl‐4′‐cyanobiphenyl) + multi‐walled carbon nanotubes (MWCNTs) composite materials. The concentration of MWCNTs was varied within 0.025 and 1 wt.%. The unmodified (o) and modified (m) MWCNTs were used. The mild milling was applied for shortening length of MWCNTs. Direct microscopic observation of composites at different concentrationsCof MWCNTs evidenced the presence of aggregation and percolation processes. Formation of percolation networks was observed atCp≈ 0.025–0.05% wt andC=Cp≈ 0.1–0.25% wt foro‐MWCNTs andm‐MWCNTs composites, respectively. Increase of the percolation threshold form‐MWCNTs, possibly, reflected their smaller aspect ratior. The conductivity exponents were approximately the same (t≈ 3.3 ± 0.1) for botho‐MWCNTs andm‐MWCNTs. The microstructure of MWCNT aggregates was not stable in time. The initially formed loose aggregates (L‐aggregates) transformed into the more compact C‐aggregates during the incubation time of one week. The incubation resulted in decrease of anisotropy, change in phase behaviour near the nematic‐isotropic transition, and influenced external electric field response of the studied composite material.In dieser Arbeit werden die Mikrostruktur, die elektrische Leitfähigkeit und die Phasenübergänge in Kompositen aus 5CB (4‐pentyl‐4′‐cyanobiphenyl) und mehrschichtigen Kohlenstoff‐Nanoröhren (MWCNTs) behandelt. Die Konzentration der MWCNTs liegt im Bereich zwischen 0.025 und 1 Gew.‐%. Es wurden unbehandelte (o) und modifizierte (m) MWCNTs verwendet. Um die Länge der MWCNTs zu verkürzen, wurden sie schonend gemahlen. Die direkte mikroskopische Beobachtung der Komposite bei unterschiedlichen Konzentrationen von MWCNTs zeigte das Vorhandensein von Aggregations‐ und Perkolationsprozessen an. Die Bildung eines Perkolationsnetzwerkes wurde im Konzentrationsbereich 0,025–0,05% Gew.‐% für o‐MWCNTS und 0,1–0,25 Gew.‐% fürm‐MWCNTs beobachtet. Eine Erhöhung der Perkolationsschwelle für diem‐MWCNTs könnte mit dem kleineren Aspektverhältnis r zusammenhängen. Die Leitfähigkeitsexponenten sind für beide MWCNTs ungefähr gleich (t≈ 3,3 ± 0,1). Die Mikrostruktur der MWCNT Aggregate war zeitlich nicht stabil. Die urspünglich gebildeten losen Aggregate (L‐Aggregate) wandeln sich in die mehr kompakten Aggregate (C‐Aggregate) während der Inkubation innerhalb von einer Woche um. Die Inkubation führt zu einer Abnahme der Anisotropie, einem Wechsel der Phase in der Nähe der nematischen‐isotropen Umwandlung und beeinflusst die Antwort auf ein externes elektrisches Feld der studierten Kompositmaterialien.
Electronic structure and temperature dependence of the linear size of the nanoscale magnetic domains in a disordered bcc‐Fe‐Co alloy
Authors: Len E. G. , Melnyk I. M. , Repetsky S. P. , Lizunov V. V. , Tatarenko V. A. 
Published: February 2011

AbstractThe formation of the homogeneous magnetic short‐range‐ordered regions in disordered bcc‐Fe0.5Co0.5 alloy under the influence of the electron‐energy spectrum realignment with temperature is considered. For the description of electron states in a crystal, the multiband tight‐binding model and the developed method for the cluster expansion of Green's functions and thermodynamic potential of a disordered crystal were applied. Within the scope of the mentioned approach, calculations of both the electron‐energy spectrum and the temperature‐dependent equilibrium values of the pair‐wise magnetic‐correlation parameters of disordered bcc‐Fe0.5Co0.5 alloy were performed. The equilibrium values of parameters of magnetic and interatomic correlations were obtained at minimum free energy.Die Bildung von homogenen magnetisch über kurze Distanzen geordneten Regionen in ungeordneten kubisch raumzentrierten Fe0.5Co0.5‐Legierungen wurde unter dem Einfluss der Ausrichtung des Elektronenenergiespektrums mit der Temperatur untersucht. Für die Beschreibung der elektronischen Zustände im Kristall wurden das tight‐binding‐Modell, die Methode der Cluster‐Ausdehnung der Greenschen Funktion und das thermodynamische Potenzial von ungeordneten Kristallen benutzt. Im Rahmen der erwähnten Ansätze wurden die Berechnungen sowohl der Elektronenergiespektren als auch der temperaturabhängigen Gleichgewichtswerte der paarweise magnetischen Korrelationsparameter von ungeordnetem bcc‐Fe0.5Co0.5‐Legierungen durchgeführt. Die Gleichgewichtsparameter der magnetischen und interatomischen Korrelationen wurden unter der Bedingung erhalten, dass die freie Energie minimiert wurde.
Structure and properties of C60 fullerene films with titanium atoms
Authors: Shpilevsky E.M. , Shpilevsky M.E. , Prylutskyy Y.I. , Matzuy L.Y. , Zakharenko M.I. , Le Normand F. 
Published: February 2011

AbstractStructure, mechanical and electrical properties of thin films prepared by means of co‐deposition of fullerenes C60 and titanium were studied. The obtained results show the potential applicability of titanium‐fullerene films as electrotechnical materials and coatings.Die Struktur und die mechanischen und elektrischen Eigenschaften von dünnen Fulleren C60‐Titan‐Schichten, die über Abscheidungsverfahren hergestellt wurden, wurden untersucht. Die erzielten Ergebnisse zeigen mögliche Anwendungen von Titan‐Fulleren‐Filmen als elektrotechnische Materialien und Beschichtungen.
Simulation of percolation threshold in composites filled with conducting particles of various morphologies
Authors: Vovchenko L. , Vovchenko V. 
Published: February 2011

AbstractThree‐dimensional (3‐D) Monte Carlo simulation has been performed for predicting the percolation threshold in electrical conductivity of polymer composites filled with randomly oriented conductive particles of various morphologies. The conductive fillers like graphite nanoplatelets have been simulated as interpenetrating thin disks and oblate ellipsoids of revolution. For large aspect ratios we find close agreement between disks and oblate ellipsoids of revolution for the average number of bonds per object BC ≈ 2.3, that is in agreement with previous calculations for other shapes of filler (e. g. oblate prisms). The vermicular particles of thermoexfoliated graphite (TEG) have been simulated as the chains of disks jointed in a special manner. The values of percolation threshold have been calculated for various configuration of graphite chains (fragments of vermicular TEG particles) using the Monte Carlo method. The percolation threshold was shown to be determined by the number of disks m and angle between connected disks. It was found that critical volume fraction strongly depends on disks' aspect ratio ε, their orientation within a chain and length of this chain: ϕc decreases with increase of m and ε. The comparison of numerical results with our previous experimental data showed a reasonably good agreement.Die dreidimensionale (3‐D) Monte‐Carlo‐Simulation wurde zur Ermittlung der Perkolationsschwelle bei der elektrischen Leitfähigkeit von Polymer‐Kompositen, die mit regellos orientierten leitfähigen Teilchen unterschiedlicher Struktur gefüllt sind, eingesetzt. Leitfähige Füllstoffe wie Graphit‐Nanoplatten werden als durchdringende Dünnplatten und abgeplattete Sphäroide simuliert. Bei den großen Seitenverhältnissen wurde eine gute Übereinstimmung zwischen Platten und abgeplatteten Sphäroiden für die Durchschnittszahl der Verbindungen pro Objekt BC ≈ 2.3, entsprechend den vorigen Berechnungen für die anderen ähnlichen Formen wie abgeplattete Prismen gefunden. Weiterhin wurden die fadenförmigen Teilchen eines thermoexfolierten Graphits als Ketten von den auf besondere Weise verbundenen m Platten simuliert. Durch das Monte‐Carlo‐Verfahren wurde die Perkolationsschwelle für unterschiedliche Formen von Graphit‐Verbindungen (Bestandteile der wurmförmigen TEG‐Teilchen), bestimmt von m‐Zahl der Platten und vom Winkel zwischen den verbundenen Platten, berechnet. Es wurde festgestellt, dass die Fraktion des kritischen Volumens von den Platten‐Seitenverhältnissen ε, der Platten‐Orientierung in der Kette und von der Ketten‐Länge abhängig ist: ϕc wird durch die Erhöhung von m und ε reduziert. Die numerischen Ergebnisse wurden dann mit den experimentellen Werten verglichen.
Persistent photocurrent and defects in TlBr
Authors: Kažukauskas V. , Ziminskij A. , Bozhko V. , Muronchuk G. 
Published: February 2011

AbstractWe had observed the persistent photoconductivity in TlBr. The long lasting current relaxations took place after the band‐to‐band light excitation at the temperatures below about 200 K. It was demonstrated by the thermally stimulated current method that this phenomenon is related to the trapping states with the thermal activation energy of 0.08–0.12 eV. Moreover, upon filling of the traps the enhanced photoconductivity was induced that could be thermally quenched above about 180 K. The quenching of the photoconductivity is initiated by the emptying of the trapping states with the activation energy of 0.63–0.65 eV.Es wurde eine persistente Photoleitfähigkeit in TlBr beobachtet. Die langzeitigen Strom‐Relaxationen fanden auch nach der Band‐zu‐Band Lichtanregung bei Temperaturen unter 200 K statt. Bei der Anwendung der Methode des thermisch stimulierten Stroms wurde gezeigt, dass dieser Effekt durch Zustände mit thermischen Aktivierungsenergien von 0.08–0.12 eV verursacht werdenkönnte. Darüber hinaus führte eine Füllung dieser Zustände zu der erhöhten Photoleitfähigkeit. Dieser Zustand konnte bei Temperaturen über 180 K thermisch gelöscht werden. Die Löschung der Photoleitfähigkeit erfolgte bei der Entleerung der Zustände mit Aktivierungsenergien von 0.63–0.65 eV.
Characterization of carbon black‐filled immiscible polypropylene/polystyrene blends
Authors: Tan Yeqiang , Song Yihu , Cao Qing , Zheng Qiang 
Published: February 2011

AbstractThe electrical and rheological behaviors of carbon black (CB)‐filled immiscible polypropylene (PP)/polystyrene (PS) blends were investigated. The compounding sequence influences the phase morphology of the ternary CB/PP/PS composites and the distribution of CB aggregates. Simultaneous measurements of resistance and dynamic modulus were carried out to monitor the phase coalescence of the ternary composites and CB migration and agglomeration in the PS phase during annealing at temperatures above the melting point of PP. The variation of resistivity is mainly attributed to CB agglomeration in the PS phase and the interfacial region, while the variation of dynamic modulus is regarded as the superimposition of the phase coalescence and CB agglomeration in the PS phase. The ternary composites with the majority of CB particles distributed in the interfacial region show the lowest conductive percolation threshold and the most stable resistivity–temperature performance during heating–cooling cycles. Copyright © 2011 Society of Chemical Industry
Proteomic characterization of the multiple forms of the PLAs from the venom of the social wasp Polybia paulista
Authors: dos Santos Lucilene Delazari , da Silva Menegasso Anally Ribeiro , dos Santos Pinto José Roberto Aparecido , Santos Keity Souza , Castro Fabio Morato , Kalil Jorge Elias , Palma Mario Sergio 
Published: February 2011

AbstractThe phospholipases A1 (PLA1s) from the venom of the social wasp Polybia paulista occur as a mixture of different molecular forms. To characterize the molecular origin of these structural differences, an experimental strategy was planned combining the isolation of the pool of PLAs from the wasp venom with proteomic approaches by using 2‐D, MALDI‐TOF‐TOF MS and classical protocols of protein chemistry, which included N‐ and C‐terminal sequencing. The existence of an intact form of PLA1 and seven truncated forms was identified, apparently originating from controlled proteolysis of the intact protein; in addition to this, four of these truncated forms also presented carbohydrates attached to their molecules. Some of these forms are immunoreactive to specific‐IgE, while others are not. These observations permit to raise the hypothesis that naturally occurring proteolysis of PLA1, combined with protein glycosylation may create a series of different molecular forms of these proteins, with different levels of allergenicity. Two forms of PLA2s, apparently related to each other, were also identified; however, it was not possible to determine the molecular origin of the differences between both forms, except that one of them was glycosylated. None of these forms were immunoreactive to human specific IgE.
Mining the soluble chloroplast proteome by affinity chromatography
Authors: Bayer Roman G. , Stael Simon , Csaszar Edina , Teige Markus 
Published: February 2011

AbstractChloroplasts are fundamental organelles enabling plant photoautotrophy. Besides their outstanding physiological role in fixation of atmospheric CO2, they harbor many important metabolic processes such as biosynthesis of amino acids, vitamins or hormones. Technical advances in MS allowed the recent identification of most chloroplast proteins. However, for a deeper understanding of chloroplast function it is important to obtain a complete list of constituents, which is so far limited by the detection of low‐abundant proteins. Therefore, we developed a two‐step strategy for the enrichment of low‐abundant soluble chloroplast proteins from Pisum sativum and their subsequent identification by MS. First, chloroplast protein extracts were depleted from the most abundant protein ribulose‐1,5‐bisphosphate carboxylase/oxygenase by SEC or heating. Further purification was carried out by affinity chromatography, using ligands specific for ATP‐ or metal‐binding proteins. By these means, we were able to identify a total of 448 proteins including 43 putative novel chloroplast proteins. Additionally, the chloroplast localization of 13 selected proteins was confirmed using yellow fluorescent protein fusion analyses. The selected proteins included a phosphoglycerate mutase, a cysteine protease, a putative protein kinase and an EF‐hand containing substrate carrier protein, which are expected to exhibit important metabolic or regulatory functions.
2‐D DIGE analysis of the mitochondrial proteome from human skeletal muscle reveals time course‐dependent remodelling in response to 14 consecutive days of endurance exercise training
Authors: Egan Brendan , Dowling Paul , O'Connor Paul L. , Henry Michael , Meleady Paula , Zierath Juleen R. , O'Gorman Donal J. 
Published: February 2011

AbstractAdaptation of skeletal muscle to repeated bouts of endurance exercise increases aerobic capacity and improves mitochondrial function. However, the adaptation of human skeletal muscle mitochondrial proteome to short‐term endurance exercise training has not been investigated. Eight sedentary males cycled for 60 min at 80% of peak oxygen consumption (VO2peak) each day for 14 consecutive days, resulting in an increase in VO2peak of 17.5±3.8% (p<0.01). Mitochondria‐enriched protein fractions from skeletal muscle biopsies taken from m. vastus lateralis at baseline, and on the morning following the 7th and 14th training sessions were subjected to 2‐D DIGE analysis with subsequent MS followed by database interrogation to identify the proteins of interest. Thirty‐one protein spots were differentially expressed after either 7 or 14 days of training (ANOVA, p<0.05). These proteins included subunits of the electron transport chain, enzymes of the tricarboxylic acid cycle, phosphotransfer enzymes, and regulatory factors in mitochondrial protein synthesis, oxygen transport, and antioxidant capacity. Several proteins demonstrated a time course‐dependent induction during training. Our results illustrate the phenomenon of skeletal muscle plasticity with the extensive remodelling of the mitochondrial proteome occurring after just 7 days of exercise training suggestive of enhanced capacity for adenosine triphosphate generation at a cellular level.
Generation of well‐defined clickable glycopolymers from aqueous RAFT polymerization of isomaltulose‐derived acrylamides
Authors: Abdelkader Ouaiss , Moebs‐Sanchez Sylvie , Queneau Yves , Bernard Julien , Fleury Etienne 
Published: February 2011

AbstractOriginal carbohydrate‐based acrylamides bearing one azide group in C‐2 or C‐6 position namely, 2‐[(2‐deoxy‐2‐azido‐α‐D‐mannopyranosyloxy)ethanamido]‐ethyl acrylamide (II) and 2‐[(6‐deoxy‐6‐azido‐α‐D‐glucopyranosyloxy)ethanamido]‐ethyl acrylamide (III), and their azide‐free analogue, 2‐[(α‐D‐glucopyranosyloxy)ethanamido]‐ethyl acrylamide (I), have been designed. Whereas the reversible addition fragmentation chain transfer (RAFT) process ensured the preparation of well‐defined glycopolymers from I, the polymerization of monomers II and III proved to be challenging at temperatures compatible with a thermally initiated radical process, due to the presumed concomitant 1,3‐cycloaddition reactions between the azide and the acrylamide moieties. In contrast to III, for which no polymer could be obtained under any conditions, performing the RAFT polymerization of II at 30 °C clearly favored the radical polymerization and conferred a controlled character to the process, affording well‐defined azide‐functionalized glycopolymers and block copolymers. The presence of numerous azide moieties was finally exploited to introduce carbohydrates onto the glycopolymer backbone through copper catalyzed azide‐alkyne cycloaddition. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Design and synthesis of dithieno[3,2‐b:2′3′‐d]pyrrole‐based conjugated polymers for photovoltaic applications: consensus between low bandgap and low HOMO energy level
Authors: Shi Min‐Min , Deng Dan , Chen Lin , Ling Jun , Fu Lei , Hu Xiao‐Lian , Chen Hong‐Zheng 
Published: February 2011

AbstractA strategy of the fine‐tuning of the degree of intrachain charge transfer and aromaticity of polymer backbone was adopted to design and synthesize new polymers applicable in photovoltaics. Three conjugated polymers P1, P2, and P3 were synthesized by alternating the electron‐donating dithieno[3,2‐b:2′3′‐d]pyrrole (D) and three different electron‐accepting (A) segments (P1: N‐(2‐ethylhexyl)phthalimide; P2: 1,4‐diketo‐3,6‐diphenylpyrrolo[3,4‐c]pyrrole; and P3: thiophene‐3‐hexyl formate) in the polymer main chain. Among the three polymers, P2 possessed the broadest absorption band ranging from 300 to 760 nm, the lowest bandgap (1.63 eV), and enough low HOMO energy level (−5.27 eV) because of the strong intrachain charge transfer from D to A units and the appropriate extent of quinoid state in the main chain of P2, which was convinced by the theoretical simulation of molecular geometry and front orbits. Photovoltaic study of solar cells based on the blends of P1–P3 and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) demonstrated that P2:PCBM exhibited the best performance: a power conversion efficiency of 1.22% with a high open‐circuit voltage (VOC) of 0.70 V and a large short‐circuit current (ISC) of 5.02 mA/cm2 were achieved. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Synthesis of polynorbornene‐poly(tert‐butyl acrylate) nanoparticles with original morphologies by tandem ROMP and ATRP in microemulsion
Authors: Nguyen Minh Ngoc , Mougnier Sébastien‐Jun , Ibarboure Emmanuel , Heroguez Valérie 
Published: February 2011

AbstractComposite latex particles based on homopolymers and graft‐copolymers composed of polynorbornene (PNB) and poly(tert‐butyl acrylate) (PtBA) were synthesized in microemulsion conditions by simultaneous combination of two distinct methods of polymerization: Ring‐opening metathesis polymerization (ROMP) and atom transfer radical polymerization (ATRP). Only one commercial compound (first generation Grubbs catalyst) was used to initiate the ROMP of norbornene (NB) and activate the ATRP of tert‐butyl acrylate (tBA). Well‐defined nanoparticles with hydrodynamic diameters smaller than 50 nm were prepared with original morphologies depending on the monomer compositions, the type of combination (polymer blend or graft‐copolymer), and the conditions of microemulsion polymerizations. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011