bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Polycrystalline Approach to the Cyclic Behaviour of f.c.c. Alloys – Intra‐Granular Heterogeneity
Authors: Feaugas Xavier , Pilvin Philippe 
Published: July 2009

AbstractFor several decades, the plastic deformation mechanisms of f.c.c. metals under cyclic loading have received considerable attention. The extensive work on this subject has gradually lead to the identification of the physical processes to be included in a formal scheme of fatigue behavior. Accordingly, we propose a review of the physical mechanisms of plastic deformation in f.c.c. metals and alloys to define the state‐of‐the‐art and motivate future studies. The aim is to demonstrate the importance of a good knowledge of the heterogeneous nature of deformation at the intra‐granular scale in defining a physical model of cyclic behavior. A large characterization of the different stages associated with the evolution of heterogeneous dislocation structures during tensile and cyclic loadings is given for an austenitic stainless steel AISI 316L. A unified view of these various structures is proposed in the form of a modified Pedersen's map [εmax = f(εpcum), where εmax is the maximum plastic strain and εpcum the cumulative plastic strain] in the case of tensile loading and different kinds of cyclic loading: uni‐axial and multi‐axial tests under stress or strain amplitude control. The specificities of each domain defined in the map are discussed in terms of long‐range internal stresses in order to formalize, in a simple composite scheme, the intra‐granular stress–strain field. The importance of taking into account this scheme and the nature of the different dislocations populations in a polycrystalline model is illustrated.
An Overview of the Anatomy of Crystal Plasticity Models
Authors: Cailletaud Georges 
Published: July 2009

AbstractSingle crystals, polycrystals, and DS alloys can be modeled in the same framework by means of crystal plasticity. This paper wants to show the common features of the different approaches on the grain level, and the additional assumptions that are needed to derive polycrystal or DS models. Phenomenological rules are introduced for representing the hardening in the single crystal constitutive equations. Series of examples are given to illustrate the capabilities of the various approaches that are mainly related to the crystallographic character, and to the fact that the macroscopic yield locus is not predefined, but built from a collection of linear yield conditions.
Effect of Electric Field on Coulomb‐Stabilized Excitons in Host/Guest Systems for Deep‐Blue Electrophosphorescence
Authors: Haneder Stephan , Da Como Enrico , Feldmann Jochen , Rothmann Michael M. , Strohriegl Peter , Lennartz Christian , Molt Oliver , Münster Ingo , Schildknecht Christian , Wagenblast Gerhard 
Published: July 2009

AbstractHere, a study of the electric field induced quenching on the phosphorescence intensity of a deep‐blue triplet emitter dispersed in different host materials is presented. The hosts are characterized by a higher triplet excitonic level with respect to the emitter, ensuring efficient energy transfer and exciton confinement, whereas they differ in the highest occupied molecular orbital (HOMO) alignment, forming type I and type II host/guest heterostructures. While the type I structure shows negligible electric field induced quenching, a quenching up to 25% for the type II at a field of 2 MV/cm is reported. A similar quenching behaviour is also reported for thin films of the pure emitter, revealing an important luminescence loss mechanism for aggregated emitter molecules. These results are interpreted by considering Coulomb stabilized excitons in the type II heterostructure and in the pure emitter, that become very sensitive to dissociation upon application of the field. These results clarify the role of external electric field quenching on the phosphorescence of triplet emitters and provide useful insights for the design of deep‐blue electrophosphorescent devices with a reduced efficiency roll‐off.
Electric‐Field‐Assisted Nanostructuring of a Mott Insulator
Authors: Dubost Vincent , Cren Tristan , Vaju Cristian , Cario Laurent , Corraze Benoit , Janod Etienne , Debontridder François , Roditchev Dimitri 
Published: July 2009

AbstractHere, the first experimental evidence for a strong electromechanical coupling in the Mott insulator GaTa4Se8 that allows highly reproducible nanoscaled writing by means of scanning tunneling microscopy (STM) is reported. The local electric field across the STM junction is observed to have a threshold value above which the clean (100) surface of GaTa4Se8 becomes mechanically instable: at voltage biases >1.1 V, the surface suddenly inflates and comes in contact with the STM tip, resulting in nanometer‐sized craters. The formed pattern can be indestructibly “read” by STM at a lower voltage bias, thus allowing 5 Tdots inch−2 dense writing/reading at room temperature. The discovery of the electromechanical coupling in GaTa4Se8 might give new clues in the understanding of the electric pulse induced resistive switching recently observed in this stoichiometric Mott insulator.
Controlling Electron and Hole Charge Injection in Ambipolar Organic Field‐Effect Transistors by Self‐Assembled Monolayers
Authors: Cheng Xiaoyang , Noh Yong‐Young , Wang Jianpu , Tello Marta , Frisch Johannes , Blum Ralf‐Peter , Vollmer Antje , Rabe Jürgen P. , Koch Norbert , Sirringhaus Henning 
Published: July 2009

AbstractControlling contact resistance in organic field‐effect transistors (OFETs) is one of the major hurdles to achieve transistor scaling and dimensional reduction. In particular in the context of ambipolar and/or light‐emitting OFETs it is a difficult challenge to obtain efficient injection of both electrons and holes from one injecting electrode such as gold since organic semiconductors have intrinsically large band gaps resulting in significant injection barrier heights for at least one type of carrier. Here, systematic control of electron and hole contact resistance in poly(9,9‐di‐n‐octylfluorene‐alt‐benzothiadiazole) ambipolar OFETs using thiol‐based self‐assembled monolayers (SAMs) is demonstrated. In contrast to common believe, it is found that for a certain SAM the injection of both electrons and holes can be improved. This simultaneous enhancement of electron and hole injection cannot be explained by SAM‐induced work‐function modifications because the surface dipole induced by the SAM on the metal surface lowers the injection barrier only for one type of carrier, but increases it for the other. These investigations reveal that other key factors also affect contact resistance, including i) interfacial tunneling through the SAM, ii) SAM‐induced modifications of interface morphology, and iii) the interface electronic structure. Of particular importance for top‐gate OFET geometry is iv) the active polymer layer thickness that dominates the electrode/polymer contact resistance. Therefore, a consistent explanation of how SAM electrode modification is able to improve both electron and hole injection in ambipolar OFETs requires considering all mentioned factors.
Bismuth‐Doped Ceria, Ce0.90Bi0.10O2: A Selective and Stable Catalyst for Clean Hydrogen Combustion
Authors: Beckers Jurriaan , Lee Adam F. , Rothenberg Gadi 
Published: July 2009

AbstractBismuth‐doped cerias are successfully applied as solid “oxygen reservoirs” in the oxidative dehydrogenation of propane. The lattice oxygen of the ceria is used to selectively combust hydrogen from the dehydrogenation mixture at 550 °C. This process has three key advantages: it shifts the dehydrogenation equilibrium to the desired products side, generates heat, aiding the endothermic dehydrogenation, and simplifies product separation (water vs. hydrogen). Furthermore, the process is safer, since it uses the catalyst’s lattice oxygen instead of gaseous oxygen. We show here that bismuth‐doped cerias are highly active and stable towards hydrogen combustion, and explore four different approaches for optimising their application in the oxidative dehydrogenation of propane: first, the addition of extra hydrogen which lowers hydrocarbon conversion by suppressing both combustion and coking; second, the addition of tin which completely inhibits coking; third, the addition of platinum which increases selectivity, but at the expense of lower activity. The best results are obtained through tuning the reaction temperature. At 400 °C, high activity and selectivity were obtained for the bismuth‐doped ceria Ce0.90Bi0.10O2. Here, 90% of the hydrogen feed is converted at 98% selectivity. This optimal reaction temperature can be rationalised from the hydrogen and propene temperature‐programmed reduction (TPR) profiles: 400 °C lies above the reduction maximum of hydrogen, yet below that of propene. That is, this temperature is sufficiently high to facilitate rapid hydrogen combustion, but low enough to prevent hydrocarbon conversion.
A synonymous mutation in TCOF1 causes Treacher Collins syndrome due to mis‐splicing of a constitutive exon
Authors: Macaya D. , Katsanis S.H. , Hefferon T.W. , Audlin S. , Mendelsohn N.J. , Roggenbuck J. , Cutting G.R. 
Published: July 2009

AbstractInterpretation of the pathogenicity of sequence alterations in disease‐associated genes is challenging. This is especially true for novel alterations that lack obvious functional consequences. We report here on a patient with Treacher Collins syndrome (TCS) found to carry a previously reported mutation, c.122C > T, which predicts p.A41V, and a novel synonymous mutation, c.3612A > C. Pedigree analysis showed that the c.122C > T mutation segregated with normal phenotypes in multiple family members while the c.3612A  >  C was de novo in the patient. Analysis of TCOF1 RNA in lymphocytes showed a transcript missing exon 22. These results show that TCS in the patient is due to haploinsufficiency of TCOF1 caused by the synonymous de novo c.3612A > C mutation. This study highlights the importance of clinical and pedigree evaluation in the interpretation of known and novel sequence alterations. © 2009 Wiley‐Liss, Inc.
Epoxidöffnungskaskaden zur Synthese polycyclischer Polyether‐Naturstoffe
Authors: Vilotijevic Ivan , Jamison Timothy F. 
Published: July 2009

AbstractDie polycyclischen Strukturelementevon Polyether‐Naturstoffen können in einigen Fällen bis auf ihren Ursprung in der Biosynthese zurückverfolgt werden, in anderen, weniger gut verstandenen Fällen jedoch nur auf vorgeschlagene Biosynthesewege, die spekulative Epoxidöffnungskaskaden vorsehen. In diesem Aufsatz wird zusammengefasst, wie solche Reaktionskaskaden zur Synthese polycyclischer Polyether und verwandter Naturstoffe genutzt wurden.magnified imagePolycyclische Polyether‐Naturstoffe sind wegen ihrer faszinierenden Struktur und ihrer biologischen Eigenschaften von besonderem Interesse. Letztere umfassen potenziell therapeutische antibiotische und fungizide Wirkungen sowie Antikrebswirkungen und außerdem eine starke Giftwirkung bis hin zur Letalität. Die polycyclischen Strukturelemente dieser Verbindungsklasse können in einigen Fällen bis auf ihren Ursprung in der Biosynthese zurückverfolgt werden, in anderen, weniger gut verstandenen Fällen jedoch nur auf vorgeschlagene Biosynthesewege, die spekulative Epoxidöffnungskaskaden vorsehen. In diesem Aufsatz wird zusammengefasst, wie solche Reaktionskaskaden zur Synthese polycyclischer Polyether und verwandter Naturstoffe genutzt wurden.
A Persistent α‐Fluorocarbanion and Its Analogues: Preparation, Characterization, and Computational Study
Authors: Prakash G. K. Surya , Wang Fang , Shao Nan , Mathew Thomas , Rasul Golam , Haiges Ralf , Stewart Timothy , Olah George A. 
Published: July 2009

AbstractStarkes Fluor: In Einklang mit theoretischen Studien zu α‐Fluorcarbanionen ergab eine Röntgenstrukturanalyse für das α‐Fluorbis(phenylsulfonyl)methid‐Anion eine pyramidale Konfiguration (siehe Bild). Anspruchsvolle Rechnungen und NMR‐spektroskopische Studien zeigten, dass elektronenziehende Substituenten die Eigenschaften von Bis(phenylsulfonyl)methid‐Anionen entscheidend beeinflussen.magnified image
A Symmetry‐Based Concise Formal Synthesis of Platencin, a Novel Lead against “Superbugs”
Authors: Ghosh Arun K. , Xi Kai 
Published: July 2009

AbstractRascher Zugang: Eine knappe und effiziente formale Synthese von Platencin in neun Stufen nutzt kommerziell erhältliches Ausgangsmaterial und nur eine Schutzgruppe. Die basenkatalysierte Michael‐Cyclisierung der Vorstufe 1 lieferte das Schlüsseldiketon 2, das über die radikalische Zwischenstufe 3 in den gewünschten hydrophoben Strukturteil 4 überführt wurde.magnified image
Innentitelbild: Charge‐Conversional Polyionic Complex Micelles—Efficient Nanocarriers for Protein Delivery into Cytoplasm (Angew. Chem. 29/2009)
Authors: Lee Yan , Ishii Takehiko , Cabral Horacio , Kim Hyun Jin , Seo Ji‐Hun , Nishiyama Nobuhiro , Oshima Hiroki , Osada Kensuke , Kataoka Kazunori 
Published: July 2009

AbstractSehr effizient verläuft der Proteintransport ins Cytoplasma, den K. Kataoka et al. auf S. 5413 ff. beschreiben. Die Stabilität der Micellen aus Protein und polyionischem Blockcopolymerkomplex (PIC) wurde durch eine Zunahme der Ladungsdichte des Proteins durch reversible Modifikation mithilfe von Citaconamid und cis‐Aconitamid erhöht. Die rasche Änderung der Proteinladung in Endosomen führte zur Dissoziation der PIC‐Micellen und zum effizienten Verlassen der Endosome.magnified image
A Persistent α‐Fluorocarbanion and Its Analogues: Preparation, Characterization, and Computational Study
Authors: Prakash G. K. Surya , Wang Fang , Shao Nan , Mathew Thomas , Rasul Golam , Haiges Ralf , Stewart Timothy , Olah George A. 
Published: July 2009

AbstractFluoro power: In agreement with theoretical studies on α‐fluorocarbanions an X‐ray crystal structure shows the α‐fluorobis(phenylsulfonyl)methide anion adopts a pyramidal configuration (see picture). High‐level calculations and NMR spectroscopy studies demonstrate that electron‐withdrawing substituents play a crucial role in modulating the properties of bis(phenylsulfonyl)methide anions.magnified image
Structural Crystallography of Inorganic Oxysalts.IUCr Monographs on Crystallography No. 22. By Sergey V. Krivovichev.
Authors: Albrecht‐Schmitt Thomas 
Published: July 2009

AbstractOxford University Press, Oxford 2009. 320 pp., hardcover, $ 130.00.—ISBN 978‐0199213207magnified image
A Symmetry‐Based Concise Formal Synthesis of Platencin, a Novel Lead against “Superbugs”
Authors: Ghosh Arun K. , Xi Kai 
Published: July 2009

AbstractQuick access: A concise and efficient formal synthesis of platencin has been accomplished in nine steps from a commercially available starting material. The synthesis utilized only one protecting group. The base‐catalyzed Michael cyclization of precursor 1 afforded the key diketone 2, which was converted into the desired core structure 4 via the radical intermediate 3.magnified image
Studies on the effect of pH, temperature and metal ions on the production of pectinase from tamarind kernel powder by submerged fermentation using Aspergillus foetidus (NCIM 505)
Authors: JagadeeshBabu P. E. , Viswanathan Renuka 
Published: July 2009

AbstractFilamentous fungi Aspergillus foetidus NCIM 505 was studied for its capacity to produce exo‐pectinase in submerged fermentation (SMF) from a new substrate of tamarind kernel powder (TKP). The process was further studied to optimize the initial operating variables like pH, time and temperature. Maximum pectinolytic activity was reached at 72 h of growth and the best fungal strain was found to be A. foetidus NCIM 505. Further, to increase the production rate of pectinase, the effects of metal ions were studied. Metal ions like Cu++, Mg++, Fe++, Co++ and Zn++ at different concentrations were used. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Equilibrium and heat of adsorption of phosphine on CaCl2‐modified molecular sieve
Authors: Yu Qiongfen , Tang Xiaolong , Yi Honghong , Ning Ping , Yang Liping , Yang Lina , Yu Lili , Li Hua 
Published: July 2009

AbstractAdsorption characteristics of the virgin and CaCl2‐immersed molecular sieves at 298 K were investigated to select the adsorbent with high adsorption capacity to phosphine. Adsorption isobars and adsorption isotherms over the phosphine partial pressure and temperature ranged 0 ∼ 1000 Pa and 298 ∼ 343 K were measured. The adsorption equilibrium data for phosphine at various temperatures were fitted to Langmuir and Freundlich isotherm models and their isosteric heats of adsorption were determined by the Clausius‐Clapeyron equation. It was found the Freundlich was more suitable for description of phosphine adsorption process through calculating average absolute relative error, and the fitted result about Langmuir model showed the heterogeneous characteristics of modified adsorbent. The isosteric heat of adsorption was about 15 kJ/mol, which indicated adsorptive phosphine removal performance may be a dominant of physical adsorption being easy for desorption. The isosteric heat of adsorption decreased with an increase of the surface loading on CaCl2/5A, which means that CaCl2/5A molecular sieve had an energetically heterogeneous surface. The present study confirmed that the CaCl2/5A molecular sieves would be one of the candidates for separation and recycle of phosphine. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Influence of lanthanum stearate on the crystallization behavior of isotactic polypropylene
Authors: Guo Xiaojing , Zhao Shicheng , Xin Zhong 
Published: July 2009

AbstractThe influence of a nucleating agent, lanthanum stearate (LaSt), on the crystallization behavior of isotactic polypropylene (iPP) was investigated using differential scanning calorimetry (DSC), polarized optical microscopy (POM) and wide‐angle x‐ray scattering (WAXD). It was found that LaSt can act as a β‐nucleating agent and induce the formation of a high content of β‐form during the crystallization of iPP. The content of β‐form is greatly affected by crystallization temperature and cooling rate. High crystallization temperature and low cooling rate are favorable to the formation of β‐form. The results of isothermal crystallization kinetics show that LaSt shortens the crystallization half time (t1/2) and accelerates the crystallization of iPP. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Influence of the OMCs pore structures on the capacitive performances of supercapacitor
Authors: Nong Gu‐Zhen , Wang Hua , Li Wen‐Cui 
Published: July 2009

AbstractIn the present study, two mesoporous carbons OMC‐KIT‐6 and OMC‐SBA‐16 were nanocasted using mesoporous silica of KIT‐6 and SBA‐16 as templates and furfuryl alcohol as carbon precursor. Transmission electron microscopy (TEM) and X‐ray diffraction (XRD) characterizations confirmed that the resultant samples are mesoporous carbons, and the as‐prepared OMC‐KIT‐6 has an Ia3d ordered structure, whereas OMC‐SBA‐16 belongs to Im3m space group. The surface area and the average pore size are (1658 m2 g−1 and 3.4 nm) for OMC‐KIT‐6 and (1638 m2 g−1 and 2.9 nm) for OMC‐SBA‐16, respectively. The results of cyclic voltammograms and galvanostatic charge‐discharge tests show that these two mesoporous carbons have excellent capacitive performances. But the difference of capacitive behavior between OMC‐KIT‐6 and OMC‐SBA‐16 may be a result of the difference of pore geometries of these two carbons. In order to find out the function of mesopore in a supercapacitor, we compared the capacitive properties of mesoporous and microporous carbons; the experiment results indicated that these two kinds of carbon exhibit nearly ideal capacitive behavior at low scan rate. When the scan rate is enhanced up to 50 mV s−1 the performance of mesoporous carbon is more stable than microporous carbon. This outcome demonstrated that mesopore plays an important role in forming double layers in the electrode materials. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Effects of carbon sources on fungal morphology and lovastatin biosynthesis by submerged cultivation of Aspergillus terreus
Authors: Jia Zhihua , Zhang Xiaoli , Cao Xuejun 
Published: July 2009

AbstractThe influences of various carbon sources on fungal morphological changes and lovastatin production were investigated in submerged cultivation of a mutant of Aspergillus terreus. Lactose produced the least biomass (2.3 ± 0.15 gDCW l−1); however, the highest maximal specific lovastatin productivity (ρmax) was obtained. Glycerol achieved the highest lovastatin titer (937.5 ± 12.5 mg l−1), while soluble starch resulted in the highest biomass (12.05 ± 0.05 gDCW l−1) and the second highest lovastatin titer (501.3 ± 23.4 mg l−1). With the carbon source turning to be more easily metabolized, the values of ρmax dropped gradually while the corresponding Dp and mean filament ratio rose tardily. The value of ρmax (19.8 mg gDCW−1 d−1) was obtained in the presence of lactose while glucose resulted in the least ρmax (3.0 mg gDCW−1 d−1). This led to a 6.6‐fold decrease. The corresponding Dp and mean filament ratios appeared to reverse the effects, thus producing 1.9 and 3.3‐fold increases, respectively. The slowly utilizable carbon sources regulated the lovastatin production through both the inducement of fungal morphology differentiation and the control of metabolic regulation. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Synthesis of lauryl methacrylate star‐like polymers via ATRP
Authors: Qiu Lei , Wang Yufeng , Lin Qunfang , Zhou Xiaodong 
Published: July 2009

AbstractLauryl methacrylate (LMA) star‐like polymers were synthesized by atom transfer radical polymerization (ATRP) using the ‘arm‐first’ method. Linear poly lauryl methacrylate (PLMA) precursors were firstly prepared with ethyl α‐bromoisobutyrate (EBriB) as initiator and cuprous chloride (CuCl)/N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA) as catalyst in cyclohexanone via ATRP, and subsequently used as macromolecule initiator(MI) to synthesize star polymers in the presence of cross‐linker ethylene glycol dimethacrylate (EGDMA). Several experimental parameters, such as the PLMA arm length, the ratio of MI to cross‐linker, the addition amount and moment of cross‐linker and the reaction time for the star formation were systematically investigated. The samples were removed at regular intervals and analyzed by gel permeation chromatography (GPC) to track Mn and Mw/Mn of star‐like polymer, by which the influence of the experimental parameters on the structures of the star‐like polymers was studied. Employing shorter arm lengths and more cross‐linker could produce star‐like polymers with higher molecular weight and more arms per star. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.