bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Lower Bound on the Number of Cyclic Function Fields With Class Number Divisible byn
Authors: Pacelli Allison M. 
Published: December 2010

AbstractIn this paper, we find a lower bound on the number of cyclic function fields of prime degreelwhose class numbers are divisible by a given integern. This generalizes a previous result of D. Cardon and R. Murty which gives a lower bound on the number of quadratic function fields with class numbers divisible byn.
A Note on Detecting Algebraic Cycles
Authors: Ravindra G. V. 
Published: December 2010

AbstractThe purpose of this note is to show that the homologically trivial cycles contructed by Clemens and their generalisations due to Paranjape can be detected by the technique of spreading out. More precisely, we associate to these cycles (and the ambient varieties in which they live) certain families which arise naturally and which are defined over ℂ and show that these cycles, along with their relations, can be detected in the singular cohomology of the total space of these families.
Higher Dimensional Spaces of Functions on the Spectrum of a Uniform Algebra
Authors: Basener Richard F. 
Published: December 2010

AbstractIn this paper we introduce a nested family of spaces of continuous functions defined on the spectrum of a uniform algebra. The smallest space in the family is the uniform algebra itself. In the “finite dimensional” case, from some point on the spaces will be the space of all continuous complex-valued functions on the spectrum. These spaces are defined in terms of solutions to the nonlinear Cauchy–Riemann equations as introduced by the author in 1976, so they are not generally linear spaces of functions. However, these spaces do shed light on the higher dimensional properties of a uniform algebra. In particular, these spaces are directly related to the generalized Shilov boundary of the uniform algebra (as defined by the author and, independently, by Sibony in the early 1970s).
Simplicial Cohomology of Some Semigroup Algebras
Authors: Gourdeau F. , Pourabbas A. , White M. C. 
Published: December 2010

AbstractIn this paper, we investigate the higher simplicial cohomology groups of the convolution algebra ℓ1(S) for various semigroupsS. The classes of semigroups considered are semilattices, Clifford semigroups, regular Rees semigroups and the additive semigroups of integers greater thanafor some integera. Our results are of two types: in some cases, we show that some cohomology groups are 0, while in some other cases, we show that some cohomology groups are Banach spaces.
A Remark on a Modular Analogue of the Sato–Tate Conjecture
Authors: Kuo Wentang 
Published: December 2010

AbstractThe original Sato–Tate Conjecture concerns the angle distribution of the eigenvalues arising from non-CM elliptic curves. In this paper, we formulate amodular analogue of the Sato–Tate Conjecture and prove that the angles arising from non-CM holomorphic Hecke eigenforms with non-trivial central characters are not distributed with respect to the Sate–Tatemeasure for non-CM elliptic curves. Furthermore, under a reasonable conjecture, we prove that the expected distribution is uniform.
Linking Number of Singular Links and the Seifert Matrix
Authors: Hebda James J. , Hsieh Chun-Chung , Tsau Chichen M. 
Published: December 2010

AbstractWe extend the notion of linking number of an ordinary link of two components to that of a singular link with transverse intersections, in which case the linking number is a half-integer. We then apply it to simplify the construction of the Seifert matrix, and therefore the Alexander polynomial, in a natural way.
On the Existence of Asymptotic-lp Structures in Banach Spaces
Authors: Tcaciuc Adi 
Published: December 2010

AbstractIt is shown that if a Banach space is saturated with infinite dimensional subspaces in which all “special” n-tuples of vectors are equivalent with constants independent of n-tuples and of n, then the space contains asymptotic-lp subspaces for some 1 ≤ p ≤ ∞. This extends a result by Figiel, Frankiewicz, Komorowski and Ryll-Nardzewski.
A Novel Buffering Technique for Aqueous Processing of Zinc Oxide Nanostructures and Interfaces, and Corresponding Improvement of Electrodeposited ZnO‐Cu2O Photovoltaics
Authors: Musselman Kevin P. , Marin Andrew , Wisnet Andreas , Scheu Christina , MacManus‐Driscoll Judith L. , Schmidt‐Mende Lukas 
Published: December 2010

AbstractA novel buffering method is presented to improve the stability of zinc oxide processed in aqueous solutions. By buffering the aqueous solution with a suitable quantity of sacrificial zinc species, the dissolution of functional zinc oxide structures and the formation of unwanted impurities can be prevented. The method is demonstrated for ZnO films and nanowires processed in aqueous solutions used for the selective etching of mesoporous anodic alumina templates and the electrochemical deposition of Cu2O. In both cases, improved ZnO stability is observed with the buffering method. ZnO‐Cu2O heterojunction solar cells (bilayer and nanowire cells) synthesized using both traditional and buffered deposition methods are characterized by impedance spectroscopy and solar simulation measurements. Buffering the Cu2O deposition solution is found to reduce unwanted recombination at the heterojunction and improve the photovoltaic performance.
Inter‐ and Intramolecular Hydroamination of Unactivated Alkenes Catalysed by a Combination of Copper and Silver Salts: The Unveiling of a Brønstedt Acid Catalysis
Authors: Michon Christophe , Medina Florian , Capet Frédéric , Roussel Pascal , Agbossou‐Niedercorn Francine 
Published: December 2010

AbstractThe combined use of a copper halide, a silver salt and a phosphane ligand was applied for the catalysis of inter‐ and intramolecular hydroamination of alkenes. The reactions of unactivated olefins with nitrogen substrates were investigated. Mechanistic investigations demonstrated that the catalytic system generated a Brønsted acid which appeared to be the prominent catalytic species.
Lewis Acid‐Catalyzed CH Functionalization for Synthesis of Isoindolinones and Isoindolines
Authors: Qian Bo , Guo Shengmei , Xia Chungu , Huang Hanmin 
Published: December 2010

AbstractThe Lewis acid‐catalyzed CH functionalization of 2‐substituted azaarenes with N‐sulfonylaldimines has been developed, which provides a rapid and efficient approach for synthesis of heterocycle‐containing isoindolinones and isoindolines.
Chiral Amino Diol Derivatives as New Modular Organocatalysts for the Enantioselective α‐Chlorination of Cyclic β‐Keto Esters
Authors: Etayo Pablo , Badorrey Ramón , Díaz‐de‐Villegas María D. , Gálvez José A. 
Published: December 2010

AbstractHighly modular chiral amino diol derivatives have been used as organocatalysts in the enantioselective α‐chlorination of cyclic β‐keto esters. Optimization of the catalyst structure and the reaction conditions has allowed the synthesis of optically active α‐chlorinated products with high enantioselectivities (up to 96% ee) using inexpensive commercially available N‐chlorosuccinimide (NCS) as the chlorine source under mild conditions.
Catalytic Asymmetric Inverse‐Electron‐Demand (IED) [4+2] Cycloaddition of Salicylaldimines: Preparation of Optically Active 4‐Aminobenzopyran Derivatives
Authors: Bernardi Luca , Comes‐Franchini Mauro , Fochi Mariafrancesca , Leo Virginia , Mazzanti Andrea , Ricci Alfredo 
Published: December 2010

AbstractThe catalytic asymmetric inverse‐electron‐demand (IED) [4+2] cycloaddition of various salicylaldehyde‐derived N‐arylimines with electron‐rich alkenes in the presence of chiral BINOL‐derived phosphoric acid catalysts has been studied with the aim of obtaining optically active 4‐aminobenzopyran derivatives. Dienophiles such as 2,3‐dihydro‐2H‐furan, benzyl N‐vinylcarbamate and 2‐vinylindole have been employed.
Highly Enantioselective Zinc‐Catalyzed Friedel–Crafts Alkylation of Indoles with Ethyl Trifluoropyruvate
Authors: Hui Yonghai , Chen Weiliang , Wang Wentao , Jiang Jun , Cai Yunfei , Lin Lili , Liu Xiaohua , Feng Xiaoming 
Published: December 2010

AbstractA highly enantioselective Friedel–Crafts alkylation of indoles with ethyl trifluoropyruvate has been developed using N,N′‐dioxide‐zinc(II) complexes. Both enantiomers of the desired adducts were obtained by the use of enantiomeric ligands in excellent results (up to 99% yield and 98% ee) within 0.5 h under mild conditions. On the basis of the experimental results, a proposed working model was proposed to explain the origin of the asymmetric induction.
Synergistic Effect: Hydroalkoxylation of Allenes through Combination of Enantiopure BIPHEP‐Gold Complexes and Chiral Anions
Authors: Aikawa Kohsuke , Kojima Masafumi , Mikami Koichi 
Published: December 2010

AbstractA synergistic effect is observed for the combination of a neutral dinuclear gold complex with a chiral silver phosphate in the intramolecular hyroalkoxylation of allenes to give furan derivatives in high yields and enantioselectivities. The monocationic dinuclear gold complex affords higher catalytic activity and enantioselectivity than the neutral or dicationic digold complexes. The synergistic effect is thus highly promising to provide a guiding principle in designing an efficient chiral environment for creating an asymmetric catalyst.
Synthesis and characterization of Na‐alginate/acrylamide hydrogel and its application in dye removal
Authors: Gad Y. H. , Aly R. O. , Abdel‐Aal S. E. 
Published: December 2010

AbstractSodium‐alginate/acrylamide (Na‐alginate/AAm) cross‐linked hydrogel was prepared by using gamma irradiation. The gel content and the water absorbency behavior of the obtained hydrogel were investigated. The thermal and morphological properties of the prepared hydrogel were studied using thermogravimetric analysis and scanning electron microscopy. The thermal stability of Na‐alginate significantly changed when mixed with AAm. The adsorption of basic violet 7 dye on the prepared hydrogel was studied under different experimental conditions. The adsorption process for the basic dye was proven pH dependent. The maximum amount adsorbed (mg/g) of the Na‐alginate/AAm for the dye was found to be 78.1.0 mg/g at pH 9.0. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Cross‐linking of aqueous base‐developable, photosensitive polynorbornene
Authors: Raeis‐Zadeh Mehrsa , Elce Ed , Knapp Brian , Kohl Paul A. 
Published: December 2010

AbstractThe effect of epoxy‐based cross‐linking additives with different functionalities on the photolithographic properties, adhesion to substrates, and cross‐link density of a tetramethyl ammonium hydroxide‐developable polynorbornene‐based dielectric was investigated. Three different multifunctional epoxy additives were investigated: difunctional, trifunctional, and tetrafunctional compounds. It was found that incorporation of a small quantity (1 wt % of solution) of an ultraviolet‐absorbing tetrafunctional cross‐linker, tetraphenylol ethane tetraglycidyl ether, activated the photo‐catalyst and improved the sensitivity of a previously photosensitive polynorbornene‐based formulation by a factor of 3.7. The impact of the epoxy cross‐linkers on the physical and optical properties of the polymer formulations was evaluated. The contrast was improved from 7.37, for the control formulation, to 24.2. The polymer‐to‐substrate adhesion was also improved by addition of the tetrafunctional epoxy cross‐linker, which facilitates the development of high‐aspect‐ratio structures. Hollow‐core pillar structures in 40‐μm‐thick films with a depth‐to‐width aspect ratio of 13 : 1 were produced. The cross‐link density was studied by using swelling measurements of cured films to evaluate the average molecular weight between cross‐links. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Anticipatory approach to design robust iterative learning control for uncertain time‐delay systems
Authors: Meng Deyuan , Jia Yingmin 
Published: December 2010

AbstractThis paper is devoted to robust iterative learning control (ILC) design for time‐delay systems (TDS) with uncertainties in both model plant and delay time. An ILC law is considered by using anticipation in time to compensate for the effects of delay, which has three design parameters: the weighting function, the lead time and the learning gain. For iteration‐invariant TDS, it is shown that a necessary and sufficient condition can be obtained for the tracking error to converge for all admissible plant uncertainties. If the uncertainty is considered to be varying randomly from iteration to iteration, resulting in iteration‐varying TDS, then a necessary and sufficient condition can be derived to ensure the convergence of the expected tracking error. For TDS in both cases, it is also shown that the convergence is monotonic in the sense of the ℒ︁2‐norm, and the estimated delay is sufficiently anticipatory for the selection of the lead time to achieve the robust ILC design. Simulation results are included to verify the theoretical study.Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
Zig‐zagging into the future: the role of biofuels in India
Authors: Das Subhashree , Priess Joerg A 
Published: December 2010

AbstractIndia announced a long‐awaited and much‐needed national biofuel policy in December 2009 with a mandate of achieving 20% blending of bioethanol and biodiesel by 2017. However, while the determination of specific time‐bound targets is a crucial step in the Indian biofuel program, several aspects of the guidelines reflect uncertainty that may render the 20% target unachievable. This perspective traces the rapid changes in political strategies of biofuels in India over the last decade and reviews significant scientific progress, achieved in the same period. Our observation indicates that biofuel policies in India have followed a zigzag course interspersed with several positive initiatives, severely discouraging advocacies and occasional neglect of biofuels. The multiplicity of related policies, each partially addressing biofuel issues have amounted to increasing ambiguity.We present an analysis of the tenets of the current policy with respect to land availability, related land use, and economic and marketing institutions, which are some of the important determinants of success for the Indian biofuel program. Some recommendations emanating from the analysis are (1) to estimate of available land and land use change effects; (2) to build resilience for energy crops towards climate change; and (3) to strengthen marketing and financial mechanisms at grass‐roots level. In conclusion we emphasize the need for timely scientific assessments and the subsequent incorporation into policy formulation to enable India to achieve the overall goal of sustainable biofuel production. © 2010 Society of Chemical Industry and John Wiley & Sons, Ltd
Oxygen radicals shaping evolution: Why fatty acid catabolism leads to peroxisomes while neurons do without it
Authors: Speijer Dave 
Published: December 2010

AbstractOxygen radical formation in mitochondria is a highly important, but incompletely understood, attribute of eukaryotic cells. I propose a kinetic model in which the ratio between electrons entering the respiratory chain via FADH2 or NADH is a major determinant in radical formation. During the breakdown of glucose, this ratio is low; during fatty acid breakdown, this ratio is much higher. The longer the fatty acid, the higher the ratio and the higher the level of radical formation. This means that very long chain fatty acids should be broken down without generation of FADH2 for mitochondria. This is accomplished in peroxisomes, thus explaining their role and evolution. The model explains many recent observations regarding radical formation by the respiratory chain. It also sheds light on the reasons for the lack of neuronal fatty acid (beta‐) oxidation and for beneficial aspects of unsaturated fatty acids. Last but not least, it has very important implications for all models describing eukaryotic origins.
Asymmetric Hydrogenation of Minimally Functionalised Terminal Olefins: An Alternative Sustainable and Direct Strategy for Preparing Enantioenriched Hydrocarbons
Authors: Pàmies Oscar , Andersson Pher G. , Diéguez Montserrat 
Published: December 2010

AbstractThis account discusses the progress made in the asymmetric hydrogenation of minimally functionalised terminal olefins as a new, alternative, sustainable and direct strategy for preparing enantioenriched hydrocarbons. It discusses the latest development in catalyst design, from the initial discovery of lanthanide catalytic precursors, through the use of transition‐metal/diphosphine–iminophosphorane precursors, to the successful iridium/P,N catalytic systems.
Flexibility and Sorption Selectivity in Rigid Metal–Organic Frameworks: The Impact of Ether‐Functionalised Linkers
Authors: Henke Sebastian , Schmid Rochus , Grunwaldt Jan‐Dierk , Fischer Roland A. 
Published: December 2010

AbstractThe functionalisation of well‐known rigid metal–organic frameworks (namely, [Zn4O(bdc)3]n, MOF‐5, IRMOF‐1 and [Zn2(bdc)2(dabco)]n; bdc=1,4‐benzene dicarboxylate, dabco=diazabicyclo[2.2.2]octane) with additional alkyl ether groups of the type ‐O‐(CH2)n‐O‐CH3 (n = 2–4) initiates unexpected structural flexibility, as well as high sorption selectivity towards CO2 over N2 and CH4 in the porous materials. These novel materials respond to the presence/absence of guest molecules with structural transformations. We found that the chain length of the alkyl ether groups and the substitution pattern of the bdc‐type linker have a major impact on structural flexibility and sorption selectivity. Remarkably, our results show that a high crystalline order of the activated material is not a prerequisite to achieve significant porosity and high sorption selectivity.
Acetals as Novel Fuel Additives from Glycerol and Olefins
Authors: Neubert Lorenz , Paetzold Eckhard , Fischer Chrstine , Beller Matthias , Kragl Udo , Kragl Udo , Schümann Ulrike , Sadlowski Thomas , Kempers Peter , Schörken Ulrich 
Published: December 2010

AbstractIn einem Eintopf‐Verfahren werden aus Olefinen durch Hydroformylierung mit Synthesegas (CO/H2 = 1/1) und nachfolgende säurekatalysierte Umsetzung mit Glycerin langkettige Acetale in Ausbeuten > 95 % hergestellt. Die erhaltenen Gemische von 5‐ und 6‐Ringverbindungen stellen neuartige potenzielle Kraftstoffadditive dar. Durch Optimierung der Reaktionsbedingungen und geeignete Katalysatorwahl ([Rh(COD)]acac/Xantphos) gelingt eine hochregioselektive Hydroformylierung zu den linearen Acetalen. Zur Herstellung von ausreichenden Mustermengen wurde Glycerin mit Alkenen im 2‐L‐Autoklav und mit Aldehyden im 60‐L‐Rührreaktor umgesetzt.
The characterization of prepared organoclay materials (DDMA) and gas sorption of chlorobenzene
Authors: Jarraya Ikram , Fourmentin Sophie , Benzina Mourad , Bouaziz Samir 
Published: December 2010

AbstractIn this paper, adsorptive performance of Tunisian natural clay materials has been investigated as a potential adsorbent for Volatile Organic Compounds (VOCs). The materials used were taken from Aleg and Douiret formations in the south of Tunisia. Organoclay materials (OC) were prepared by intercalating didodecyldimethyl ammonium bromide on clay materials. This intercalation allowed the improvement of the porous texture of the studied materials. The adsorption isotherms showed that the intercalation of the didodecyldimethyl ammonium bromide on clay materials improved their adsorption capacities of chlorobenzene with an adsorption capacity up to 375 mg g−1 for calcined modified clay of Douiret.
Three‐parameter cubic equation of state for pure components of heavy oils
Authors: Kumar Ashutosh , Henni Amr 
Published: December 2010

AbstractA three‐parameter cubic equation of state for pure hydrocarbons is proposed to model PVT properties of heavy hydrocarbons found in heavy oils. Thirty hydrocarbons up to C40 and some commonly found (associated) non‐hydrocarbons in heavy oils have been used to regress the parameters. Predicted results from the proposed equation for the liquid density, vapour pressure, saturated liquid density, and saturated vapour density have been compared with the widely used Peng–Robinson (PR), Soave–Redlich–Kwong (SRK), and Patel and Teja (PT) equations of state. With the increase in carbon number in hydrocarbon, the % average absolute errors in liquid density, vapour pressure, and saturated liquid density prediction using PR, SRK, and PT equations of state were found to increase, whereas the proposed equation shows consistency in the prediction, with a % average absolute error of 2.5% only.
Kinetic study of copper cementation onto zinc using a rotating packed bed cylindrical reactor
Authors: Amin N. K. , El‐Ashtoukhy E.‐S. Z. 
Published: December 2010

AbstractThe Kinetics of copper cementation onto zinc Raschig rings in a rotating packed bed cylindrical reactors have been studied. The effect of initial concentration of copper ions, packed cylinder rotation speed and diameter of zinc Raschig rings on the rate of cementation has been investigated. The influence of zinc packing geometry (Raschig rings and cylinders), the presence of surfactant (Triton X‐100) and sand particles in the solution were also studied. The rate of cementation was found to increase with increasing cylinder rotation speed raised to a power of 0.947 and solid to liquid ratio. The rate decreases with increasing the initial copper ions concentration and the diameter of zinc Raschig rings. The rate of cementation was inhibited in solutions containing Triton X‐100. Raschig rings were found to increase the rate of cementation more than cylinders. The present reactor proved to be more efficient than the traditional solid rotating cylinder reactor for cementation reactions in view of its high area per unit volume and its high rate of mass transfer. The present data can be correlated in terms of the mass transfer coefficient of cementation by the equation: $Sh = 0.0005\quad {\mathop{\rm Re}\nolimits} {}^{0.947} \quad Sc^{0.33} $. For the conditions 13900 < Re < 70500, 2056 < Sc < 2202.Nous avons étudié la cinétique de la cémentation du cuivre sur les anneaux de Raschig en zinc dans un réacteur cylindrique à lit de garnissage rotatif. Nous avons également examiné les effets des concentrations initiales d'ions cuivre, de la vitesse de rotation du cylindre à garnissage et du diamètre des anneaux de Raschig en zinc sur le taux de cémentation. L'influence de la géométrie du garnissage en zinc (anneaux de Raschig et cylindres) ainsi que la présence de surfactant (Triton X‐100) et de particules de sable dans la solution ont également été étudiées.Il a été démontré que le taux de cémentation augmente lorsque la vitesse de rotation du cylindre augmente jusqu'à une puissance de 0,947 et un rapport solide/liquide. Le taux diminue lorsque l'on augmente la concentration initiale d'ions cuivre ainsi que le diamètre des anneaux de Raschig en zinc. Le taux de cémentation a été inhibé dans des solutions contenant du Triton X‐100. Selon les résultats, les anneaux de Raschig augmentent plus le taux de cémentation que les cylindres. Le présent réacteur a été plus efficace que les réacteurs traditionnels à cylindres rotatifs solides en matière de réactions de cémentation. Cette efficacité accrue est due à la plus grande surface par unité de volume et son taux élevé de transfert de masse. Les présentes données peuvent être corrélées en matière de coefficient de transfert de masse de cémentation par l'équation: $Sh = 0.0005\quad {\mathop{\rm Re}\nolimits} {}^{0.947} \quad Sc^{0.33} $. Pour les conditions suivantes: 13900 < Re < 70500, 2056 < Sc < 2202. © 2010 Canadian Society for Chemical Engineering