bluuebunny/crossref_metadata_2025_split huggingface dataset:
In Situ Synthesis of Ti5Si3 Matrix Nanocomposites Reinforced with Nanoparticles by High‐Energy Mechanical Alloying
Authors: Li Chuang , Gu Dongdong , Shen Yifu , Meng Guangbin , Li Yufang 
Published: March 2011

AbstractIn the present work, in situ TiN/Ti5Si3 nanocomposite powder was prepared by high‐energy mechanical alloying of a Ti and Si3N4 powder mixture via the following route: 9Ti + Si3N4 = Ti5Si3 + 4TiN. Constitution phases and microstructural features of the milled powders at different milling times were studied by XRD, SEM, and TEM. The operative formation mechanisms behind the microstructural developments were disclosed. It showed that the original Si3N4 and Ti constituents demonstrated two different reaction mechanisms during milling, i.e., a progressive mechanism of Si3N4 (≤20 h) and a speedy mechanism of Ti (≤10 h). The morphologies of the milled composite powders experienced a successive change: pre‐refining – coarsening – re‐refining on increasing the applied milling time. The variation of the operative mechanisms was ascribed to the existence/exhaustion of the ductile Ti constituent in the milling system due to the nonoccurrence/initiation of the in situ reaction. The 20 h milled powder was the typical nanocomposites featured by the nanocrystalline Ti5Si3 matrix reinforced with in situ TiN nanoparticles. The grain sizes of the in situ formed Ti5Si3 and TiN phases were generally ≤15 nm, exhibiting coherent interfacial structure between reinforcement and matrix.
Atomic Layer Deposition of Conductive Coatings on Cotton, Paper, and Synthetic Fibers: Conductivity Analysis and Functional Chemical Sensing Using “All‐Fiber” Capacitors
Authors: Jur Jesse. S. , Sweet William J. , Oldham Christopher J. , Parsons Gregory N. 
Published: March 2011

AbstractConductive coatings on complex fibrous systems are attracting interest for new electronic and other functional systems. Obtaining a quantitative conductivity value for complex surface coatings is often difficult. This work describes a procedure to quantify the effective electrical conductivity of conductive coatings on non‐conductive fibrous networks. By applying a normal force orthogonal to the current and field direction, fiber/fiber contact is improved and consistent conductance values can be measured. Nylon fibers coated with an electroless silver plating shows effective conductivity up to 1950 S cm−1, and quartz fibers coated with tungsten by atomic layer deposition (ALD) show values up to ∼1150 S cm−1. Cotton fibers and paper coated with a range of ZnO film thicknesses by ALD show effective conductivity of up to 24 S cm−1 under applied normal force, and conductivity scaled as expected with film coating thickness. Furthermore, we use the conductive coatings to produce an “all‐fiber” metal–insulator–metal capacitor that functions as a liquid chemical sensor. The ability to reliably analyze the effective conductivity of coatings on complex fiber systems will be important to design and improve performance of similar devices and other electronic textiles structures.
Uniform π‐System Alignment in Thin Films of Template‐Grown Dicarbonitrile‐Oligophenyls
Authors: Klappenberger Florian , Kühne Dirk , Marschall Matthias , Neppl Stefan , Krenner Wolfgang , Nefedov Alexei , Strunskus Thomas , Fink Karin , Wöll Christof , Klyatskaya Svetlana , Fuhr Olaf , Ruben Mario , Barth Johannes V. 
Published: March 2011

AbstractThe ordering and conformational properties of dicarbonitrile‐para‐oligophenyls are studied with complementary methods, namely X‐ray structure analysis, low‐temperature scanning tunneling microscopy, and near‐edge X‐ray absorption fine‐structure spectroscopy. The packing of the functionalized variants differs from their technologically interesting para‐oligophenyl counterparts, both in the bulk crystal phase and in thin films grown by organic molecular beam epitaxy (OMBE) under ultra‐high vacuum conditions on the Ag(111) surface. In the crystal phase, the conformation depends on the number n of phenyl rings, exhibiting an intriguing screw‐like structure in the case of n = 4 at room temperature as well as at 180 K. For OMBE‐grown thin films, the whole series acquires the same type of conformation, characterized by alternately twisted phenyl rings, similar to the pure oligophenyl species. However, for all tested molecules, the orientation of the molecular reference plane is uniform within the entire film and coincides with the surface plane. This contrasts with the herringbone ordering adopted by the phenyl backbones without the carbonitrile groups. Our results demonstrate how the functionalization of moieties with extended conjugated electron systems can help to improve the structural homogeneity in technologically relevant organic thin films.
Collective Motion of Conducting Filaments in Pt/n‐Type TiO2/p‐Type NiO/Pt Stacked Resistance Switching Memory
Authors: Kim Kyung Min , Song Seul Ji , Kim Gun Hwan , Seok Jun Yeong , Lee Min Hwan , Yoon Jung Ho , Park Jucheol , Hwang Cheol Seong 
Published: March 2011

AbstractFilamentary resistance switching (RS) is one of the more obvious and useful phenomena in the family of RS mechanisms. In filamentary RS, the long reset switching time and substantially large power consumption are the critical obstacles for microelectronic applications. In this study, an innovative solution to overcome this reset problem is suggested by stacking n‐type TiO2 and p‐type NiO films. Interestingly, in this stacked structure, the region where filament rupture and rejuvenation occurs could be arbitrarily controlled to be at any location between the interface with the metal electrode and the TiO2/NiO interface by using an appropriate switching sequence. This collective motion behavior of conducting filaments can be practically used to reduce reset switching time from ∼100 μs to ∼150 ns, with an extremely high off/on resistance ratio of ∼106.
Doping of Organic Semiconductors Using Molybdenum Trioxide: a Quantitative Time‐Dependent Electrical and Spectroscopic Study
Authors: Gwinner Michael C. , Pietro Riccardo Di , Vaynzof Yana , Greenberg Kathryn J. , Ho Peter K. H. , Friend Richard H. , Sirringhaus Henning 
Published: March 2011

AbstractDoping of organic semiconductors (OSCs) with transition metal oxides such as molybdenum trioxide (MoO3) has been used as a powerful method to overcome common issues such as contact resistance and low conductivity, which are limiting factors in organic optoelectronic devices. In this study, the mechanism and efficiency of MoO3‐induced p‐type doping in OSCs are investigated by means of simultaneous electrical and spectroscopic measurements on lateral diodes. It is demonstrated that energetic changes in the MoO3 energy levels outside vacuum can limit charge‐transfer doping and device performance. It is shown and investigated that these changes crucially depend on the OSC. The time evolution of important OSC parameters such as induced charge density, doping concentration and efficiency, conductivity and mobility, is deduced. Moreover, the energetic and chemical changes in MoO3 are investigated via ultraviolet and x‐ray photoemission spectroscopy. Combining these experiments, important conclusions are drawn on the time‐dependence and stability of MoO3‐doping of OSCs, as well as on the processing conditions and device architectures suitable for high‐performance devices.
Functional Materials for Rechargeable Batteries
Authors: Cheng Fangyi , Liang Jing , Tao Zhanliang , Chen Jun 
Published: March 2011

AbstractThere is an ever‐growing demand for rechargeable batteries with reversible and efficient electrochemical energy storage and conversion. Rechargeable batteries cover applications in many fields, which include portable electronic consumer devices, electric vehicles, and large‐scale electricity storage in smart or intelligent grids. The performance of rechargeable batteries depends essentially on the thermodynamics and kinetics of the electrochemical reactions involved in the components (i.e., the anode, cathode, electrolyte, and separator) of the cells. During the past decade, extensive efforts have been dedicated to developing advanced batteries with large capacity, high energy and power density, high safety, long cycle life, fast response, and low cost. Here, recent progress in functional materials applied in the currently prevailing rechargeable lithium‐ion, nickel‐metal hydride, lead acid, vanadium redox flow, and sodium‐sulfur batteries is reviewed. The focus is on research activities toward the ionic, atomic, or molecular diffusion and transport; electron transfer; surface/interface structure optimization; the regulation of the electrochemical reactions; and the key materials and devices for rechargeable batteries.
On the Effect of the Amorphous Silicon Microstructure on the Grain Size of Solid Phase Crystallized Polycrystalline Silicon
Authors: Sharma Kashish , Branca Annalisa , Illiberi Andrea , Tichelaar Frans D. , Creatore Mariadriana , van de Sanden Mauritius C. M. 
Published: March 2011

AbstractIn this paper the effect of the microstructure of remote plasma‐deposited amorphous silicon films on the grain size development in polycrystalline silicon upon solid‐phase crystallization is reported. The hydrogenated amorphous silicon films are deposited at different microstructure parameter values R* (which represents the distribution of SiHx bonds in amorphous silicon), at constant hydrogen content. Amorphous silicon films undergo a phase transformation during solid‐phase crystallization and the process results in fully (poly‐)crystallized films. An increase in amorphous film structural disorder (i.e., an increase in R*), leads to the development of larger grain sizes (in the range of 700–1100 nm). When the microstructure parameter is reduced, the grain size ranges between 100 and 450 nm. These results point to the microstructure parameter having a key role in controlling the grain size of the polycrystalline silicon films and thus the performance of polycrystalline silicon solar cells.
A mild and clean synthesis of alkyl azides from alkyl halides mediated by poly(4‐vinylpyridine)‐supported sodium azide under nonaqueous conditions
Authors: Karimi Zarchi Mohammad Ali , Escandari Zohreh 
Published: March 2011

AbstractAlkyl halides were efficiently converted to their corresponding alkyl azides under mild nonaqueous conditions with a polymer‐supported azide as a new polymeric reagent at room temperature at high yields and purities. All of the byproducts were removed by filtration, and pure products were obtained by the evaporation of the solvent. The spent polymeric reagent could usually be removed quantitatively and regenerated. The regenerated polymeric reagent could be reused several times. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Grafting of molecularly imprinted polymers from the surface of Fe3O4 nanoparticles containing double bond via suspension polymerization in aqueous environment: A selective sorbent for theophylline
Authors: Luo Xubiao , Deng Fang , Luo Shenglian , Tu Xinman , Yang Lixia 
Published: March 2011

AbstractMolecularly imprinted polymers (MIPs) were grafted from the surface of Fe3O4 nanoparticles containing double bond via suspension polymerization in aqueous environment, and the leakage of Fe3O4 nanoparticles from MIPs was overcome in this study. The effect of different cross‐linker on adsorption capacity of the resultant magnetic MIPs was investigated using pure trimethylolpropane trimethacrylate (TRIM) or the mixture of TRIM and divinylbenzene (DVB) as cross‐linker. Both magnetic MIPs exhibited higher adsorption capacity for the template theophylline than the corresponding non‐imprinted polymer, and Freundlich model fitted reasonably well for theophylline adsorption on both magnetic MIPs. In addition, both magnetic MIPs exhibited good recognition properties for the template theophylline versus caffeine, and the selectivity of magnetic MIPs using pure TRIM as cross‐linker (mag‐MIP‐TRIM) was much higher than those using the mixture of TRIM and DVB as cross‐linker (mag‐MIP‐TRIM and DVB). The adsorption dynamics of theophylline on both magnetic MIPs fitted well with the first‐order kinetic model, but the adsorption equilibrium on mag‐MIP‐TRIM and DVB reached faster than that on mag‐MIP‐TRIM. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Reversible phosphorylation regulation of NADPH‐linked polyol dehydrogenase in the freeze‐avoiding gall moth, Epiblema scudderiana: role in glycerol metabolism
Authors: Holden Helen A. , Storey Kenneth B. 
Published: March 2011

AbstractLarvae of the goldenrod gall moth, Epiblema scudderiana, use a freeze avoidance strategy of cold hardiness to survive the winter. A key metabolic adaption that supports subzero survival is the accumulation of large amounts of glycerol as a colligative antifreeze. Production of glycerol relies on polyol dehydrogenase (PDH) which catalyzes the NADPH‐dependent conversion of glyceraldehyde into glycerol. Kinetic analysis of PDH from E. scudderiana revealed significant changes in properties as a result of subzero temperature acclimation; the Km for glyceraldehyde in 5°C‐acclimated larvae was 7.0 mM and doubled in − 15°C‐exposed larvae. This change suggested that PDH is regulated by a state‐dependent covalent modification. Indeed, high and low Km forms could be interconverted by incubating larval extracts in vitro under conditions that stimulated either endogenous protein kinases or protein phosphatases. Protein kinase incubations doubled the Km glyceraldehyde of the 5°C enzyme, whereas protein phosphatase incubations decreased the Km of the − 15°C enzyme by about 50%. PDH was purified by ion exchange and affinity chromatography steps and then subjected to electrophoresis. Staining with ProQ Diamond phosphoprotein stain showed a much higher phosphate content of PDH from − 15°C‐acclimated larvae, a result that was further confirmed by immunoblotting that showed a much greater phosphoserine content on the − 15°C enzyme. These experiments established that PDH is regulated by state‐dependent reversible phosphorylation in E. scudderiana and suggest that this regulatory mechanism makes a significant contribution to controlling the synthesis, maintenance, and degradation of glycerol pools over the winter months. © 2011 Wiley Periodicals, Inc.
Conjugate Additions to Alkylidene Bis(Sulfoxides)
Authors: Brebion Franck , Vincent Guillaume , Chelli Saloua , Kwasnieski Ophélie , Najera Francisco , Delouvrié Bénédicte , Marek Ilan , Derat Etienne , Goddard Jean‐Philippe , Malacria Max , Fensterbank Louis 
Published: March 2011

AbstractA general study on the conjugate addition of anionic nucleophiles to alkylidene bis(sulfoxides) is presented. Alkoxides gave high yielding and diastereoselective addition reactions, which could be influenced by solvents and the counteranion. Azides provided an interesting entry into sulfinyl‐substituted triazoles. Organometallics, mainly copper reagents, proved also to be valuable nucleophiles, and complete inversion of the stereoselectivity was achieved in the addition reaction with the latter. Modelizations provide a rationale for the observed diastereoselectivity.
Large‐scale circulation anomalies associated with persistent low temperature over Southern China in January 2008
Authors: Bueh Cholaw , Shi Ning , Xie Zuowei 
Published: March 2011

AbstractA pre‐existing anticyclonic anomaly over Scandinavia/western Russia played a crucial role in the persistent low temperature event over southern China in January 2008. This anticyclonic anomaly extended eastward along the arctic coast of the Eurasian continent, and then induced the persistent low temperature over southern China. Considering that anticyclonic anomalies over Scandinavia/western Russia rarely extended eastward to central Siberia, the simultaneous presence of this feature along with the vigorous Rossby wave propagation along the African‐Asian jet stream is found to be a fundamental factor in the occurrence of the persistent event. Copyright © 2011 Royal Meteorological Society
Immunohistochemical study of human costotransverse joints: A preliminary investigation
Authors: Dedrick G.S. , Sizer P.S. , Sawyer B.G. , BrismeÈ J.M. , Smith M.P. 
Published: March 2011

AbstractThe human costotransverse joint (CTJ) is the articulation between the posterior tubercle of the ribs with the first through tenth costal facet of the thoracic transverse processes. While the CTJ is well defined anatomically and considered a synovial joint, the human CTJ as a pain generating structure is controversial and not supported from a histological perspective. The objective of the present study was to investigate the histological pain producing properties of CTJ capsule tissue. Ten micron cross‐sections at each level (1–10) were stained with H & E or immunostained with antisera against Substance P (SP), calcitonin‐gene‐related peptide (CGRP), and neuropeptide Y (NPY). Immunoreactivity was confirmed for SP, CGRP, and NPY within the CTJ tissue samples of two unembalmed male cadavers. The presence of previously mentioned neuropeptides suggests that human CTJ is capable of producing pain through somatic and autonomic nervous systems. Therefore, clinicians should consider the CTJ as a differential diagnostic possibility when examining and treating painful thoracic conditions. Clin. Anat. 24:741–747, 2011. © 2011 Wiley‐Liss, Inc.
Approaches to Enzyme and Substrate Design of the Murine Dnmt3a DNA Methyltransferase
Authors: Jurkowska Renata Z. , Siddique Abu Nasar , Jurkowski Tomasz P. , Jeltsch Albert 
Published: March 2011

AbstractDnmt3a‐C, the catalytic domain of the Dnmt3a DNA‐(cytosine‐C5)‐methyltransferase, is active in an isolated form but, like the full‐length Dnmt3a, shows only weak DNA methylation activity. To improve this activity by directed evolution, we set up a selection system in which Dnmt3a‐C methylated its own expression plasmid in E. coli, and protected it from cleavage by methylation‐sensitive restriction enzymes. However, despite screening about 400 clones that were selected in three rounds from a random mutagenesis library of 60 000 clones, we were not able to isolate a variant with improved activity, most likely because of a background of uncleaved plasmids and plasmids that had lost the restriction sites. To improve the catalytic activity of Dnmt3a‐C by optimization of the sequence of the DNA substrate, we analyzed its flanking‐sequence preference in detail by bisulfite DNA‐methylation analysis and sequencing of individual clones. Based on the enrichment and depletion of certain bases in the positions flanking >1300 methylated CpG sites, we were able to define a sequence‐preference profile for Dnmt3a‐C from the −6 to the +6 position of the flanking sequence. This revealed preferences for T over a purine at position −2, A over G at −1, a pyrimidine at +1, and A and T over G at +3. We designed one “good” substrate optimized for methylation and one “bad” substrate designed not to be efficiently methylated, and showed that the optimized substrate is methylated >20 times more rapidly at its central CpG site. The optimized Dnmt3a‐C substrate can be applied in enzymatic high‐throughput assays with Dnmt3a‐C (e.g., for inhibitor screening), because the increased activity provides an improved dynamic range and better signal/noise ratio.
Tuning the Regio‐ and Stereoselectivity of CH Activation in n‐Octanes by Cytochrome P450 BM‐3 with Fluorine Substituents: Evidence for Interactions Between a CF Bond and Aromatic π Systems
Authors: Wu Li‐Lan , Yang Chung‐Ling , Lo Feng‐Chun , Chiang Chih‐Hsiang , Chang Chun‐Wei , Ng Kok Yaoh , Chou Ho‐Hsuan , Hung Huei‐Ying , Chan Sunney I. , Yu Steve S.‐F. 
Published: March 2011

AbstractWe employed the water‐ soluble cytochrome P450 BM‐3 to study the activity and regiospecificity of oxidation of fluorinated n‐octanes. Three mutations, A74G, F87V, and L188Q, were introduced into P450 BM‐3 to allow the system to undergo n‐octane oxidation. In addition, the alanine at residue 328 was replaced with a phenylalanine to introduce an aromatic residue into the hydrophobic pocket to examine whether or not van der Waals interactions between a CF substituent in the substrate and the polarizable π system of the phenylalanine may be used to steer the positioning of the substrate within the active‐site pocket of the enzyme and control the regioselectivity and stereoselectivity of hydroxylation. Interestingly, not only was the regioselectivity controlled when the fluorine substituent was judiciously positioned in the substrate, but the electron input into the iron–heme group became tightly coupled to the formation of product, essentially without abortive side reactions. Remarkable enhancement of the coupling efficiency between electron input and product formation was observed for a range of fluorinated octanes in the enzyme even without the A328F mutation, presumably because of interactions of the CF substituent with the π system of the porphyrin macrocycle within the active‐site pocket. Evidently, tightening the protein domain containing the heme pocket tunes the distribution of accessible enzyme conformations and the associated protein dynamics that activate the iron porphyrin for substrate hydroxylation to allow the reactions mediated by the high‐valent FeIVO to become kinetically more commensurate with electron transfer from the flavin adenine dinucleotide (FAD)/flavin mononucleotide (FMN) reductase. These observations lend compelling evidence to support significant van der Waals interactions between the CF2 group and aromatic π systems within the heme pocket when the fluorinated octane substrate is bound.
Micellar Extraction of Zinc with Di(2‐ethylhexyl)phosphoric Acid and the Addition of the Cationic Surfactant Cetyltrimethylammonium Bromide
Authors: Raatz Simone , Klapper Peter , Repke Jens‐Uwe 
Published: March 2011

AbstractDurch den Zusatz von Tensiden kann die Extraktion deutlich beeinflusst werden. Für Tensidkonzentration geringfügig oberhalb der kritischen Mizellbildungskonzentration steigt die Stofftransportrate durch die Bildung inverser Mizellen und eines dadurch verursachten mizellaren Zinkextraktionsmechanismus. Anhand von Extraktionsgleichgewichten und Stoffaustauschuntersuchungen wird die Beeinflussung der Zinkextraktion mit dem Kationenaustauscher Di(2‐ethylhexyl)phosphorsäure (D2EHPA) unter Zugabe des Tensids Cetyltrimethylamoniumbromid (CTAB) aufgezeigt und phänomenologisch erläutert.
Evaluation of Readily Accessible Azoles as Mimics of the Aromatic Ring of D‐Phenylalanine in the Turn Region of Gramicidin S
Authors: van der Knaap Matthijs , Lageveen Lianne T. , Busscher Henk J. , Mars‐Groenendijk Roos , Noort Daan , Otero José M. , Llamas‐Saiz Antonio L. , van Raaij Mark J. , van der Marel Gijsbert A. , Overkleeft Herman S. , Overhand Mark 
Published: March 2011

AbstractThe influence of replacing the d‐phenylalanine residue with substituted and unsubstituted azoles on the structure and biological activity of the antibiotic gramicidin S was investigated against a representative panel of Gram‐positive and Gram‐negative bacteria strains. Substituted triazole derivatives, obtained using a convergent synthetic strategy, are as active as gramicidin S, provided that any substituent on the triazole moiety is not too large. The unsubstituted triazole derivative was biologically less active than the parent natural product, gramicidin S. In general for the triazole series, the hemolytic activity could be correlated with the antibacterial activity, that is, the higher the antibacterial activity, the higher the toxicity towards blood cells. Interestingly, its imidazole counterpart showed high antibacterial activity, combined with significantly diminished hemolytic activity.