bluuebunny/crossref_metadata_2025_split huggingface dataset:
Crystal‐Plane‐Controlled Surface Chemistry and Catalytic Performance of Surfactant‐Free Cu2O Nanocrystals
Authors: Hua Qing , Cao Tian , Bao Huizhi , Jiang Zhiquan , Huang Weixin 
Published: October 2013

AbstractSurfactant‐free Cu2O nanocrystals, including cubes exposing {100} crystal planes, octahedra exposing {111} crystal planes, and rhombic dodecahedra exposing {110} crystal planes, were used as model catalysts to study the effect of the crystal plane on the surface chemistry and catalytic performance for CO oxidation of Cu2O nanocrystals. The catalytic performance follows the order of octahedra≫rhombic dodecahedra>cubes; this suggests that Cu2O(111) is most active in catalyzing CO oxidation among Cu2O (111), (110), and (100) surfaces. CO temperature‐programmed reduction results demonstrate that Cu2O octahedra are the most easily reduced of the Cu2O cubes, octahedra, and rhombic dodecahedra. Diffuse reflectance FTIR spectra show that CO chemisorption on Cu2O nanocrystals depends on their shape and the chemisorption temperature. CO chemisorption is strongest on rhombic dodecahedra at 30 °C, but at 150 °C on octahedra. Both the reducibility and chemisorption ability of various Cu2O nanocrystals toward CO are consistent with their catalytic performance in CO oxidation. The observed surface chemistry and catalytic performance in CO oxidation of various Cu2O nanocrystals can be well correlated with their exposed crystal plane and surface composition/structure. Cu2O octahedra expose the {111} crystal plane with coordinated, unsaturated CuI sites, and thus, are most active in chemisorbing CO and catalyzing CO oxidation. These results nicely demonstrate the crystal‐plane‐controlled surface chemistry and catalytic performance of oxide catalysts.
Adsorption of HMF from Water/DMSO Solutions onto Hydrophobic Zeolites: Experiment and Simulation
Authors: Xiong Ruichang , León Marta , Nikolakis Vladimiros , Sandler Stanley I. , Vlachos Dionisios G. 
Published: October 2013

AbstractThe adsorption of 5‐hydroxymethylfurfural (HMF), DMSO, and water from binary and ternary mixtures in hydrophobic silicalite‐1 and dealuminated Y (DAY) zeolites at ambient conditions was studied by experiments and molecular modeling. HMF and DMSO adsorption isotherms were measured and compared to those calculated using a combination of grand canonical Monte Carlo and expanded ensemble (GCMC–EE) simulations. A method based on GCMC–EE simulations for dilute solutions combined with the Redlich–Kister (RK) expansion (GCMC–EE–RK) is introduced to calculate the isotherms over a wide range of concentrations. The simulations, using literature force fields, are in reasonable agreement with experimental data. In HMF/water binary mixtures, large‐pore hydrophobic zeolites are much more effective for HMF adsorption but less selective because large pores allow water adsorption because of H2O–HMF attraction. In ternary HMF/DMSO/water mixtures, HMF loading decreases with increasing DMSO fraction, rendering the separation of HMF from water/DMSO mixtures by adsorption difficult. The ratio of the energetic interaction in the zeolite to the solvation free energy is a key factor in controlling separation from liquid mixtures. Overall, our findings could have an impact on the separation and catalytic conversion of HMF and the rational design of nanoporous adsorbents for liquid‐phase separations in biomass processing.
Preparation of Sustainable Photocatalytic Materials through the Valorization of Industrial Wastes
Authors: Sugrañez Rafael , Cruz‐Yusta Manuel , Mármol Isabel , Morales Julián , Sánchez Luis 
Published: October 2013

AbstractA new value‐added material was developed from wastes to aim for appropriate waste management and sustainable development. This paper reports the valorization of industrial sandblasting operation wastes (SOWs) as new photocatalytic materials. This waste is composed of Fe2O3 (60.7 %), SiO2 (29.1 %), and Al2O3 (3.9 %) as the main components. The high presence of iron oxides was used to develop photocatalytic properties through their thermal transformation into α‐Fe2O3. The new product, SOW‐T, exhibited a good behavior towards the photochemical degradation of organic dyes. The preparation of advanced photocatalytic materials that exhibit self‐cleaning and depolluting properties was possible by the inclusion of SOW‐T and TiO2 in a cement‐based mortar. The synergy observed between both materials enhanced their photocatalytic action. To the best of our knowledge, this is the first report that describes the use of transformed wastes based on iron oxide for the photochemical oxidation of NOx gases.
Hollow AgI:Ag Nanoframes as Solar Photocatalysts for Hydrogen Generation from Water Reduction
Authors: An Changhua , Wang Jizhuang , Liu Junxue , Wang Shutao , Sun Yugang 
Published: October 2013

AbstractA facile strategy based on the principle of the Kirkendall effect has been developed to synthesize hollow nanoframes and nanoshells of AgI:Ag composites through the controlled anion‐exchange reaction between I− ions and solid AgBr:Ag (or AgCl:Ag) nanoparticles that serve as templates. Regardless of the morphologies of the template nanoparticles, they can be chemically transformed to hollow AgI:Ag structures with morphologies similar to those of the templates. The synthesized hollow AgI:Ag nanostructures can be used as efficient photocatalysts for H2 generation from water reduction and the decomposition of organic pollutants owing to the enhanced absorption of visible light by the Ag components in the hybrid nanostructures. The hollow nanostructures exhibit a higher photocatalytic performance than the corresponding solid nanoparticles possibly because of the large surface area and unique AgI/Ag interfaces associated with the hollow nanostructures.
Controlled Synthesis of Nanosized Palladium icosahedra and Their Catalytic Activity towards Formic‐Acid Oxidation
Authors: Lv Tian , Wang Yi , Choi Sang‐Il , Chi Miaofang , Tao Jing , Pan Likun , Huang Cheng Zhi , Zhu Yimei , Xia Younan 
Published: October 2013

AbstractPd icosahedra with sizes controlled in the range of 5–35 nm were synthesized in high purity through a combination of polyol reduction and seed‐mediated growth. The Pd icosahedra were obtained with purity >94 % and uniform sizes controlled in the range of 5–17 nm by using ethylene glycol as both the reductant and solvent. The studies indicate that the formation of Pd nanocrystals with an icosahedral shape was very sensitive to the reaction kinetics. The success of this synthesis relies on the use of HCl to manipulate the reaction kinetics and thus control the twin structure and shape of the resultant nanocrystals. The size of the Pd icosahedra could be further increased up to 35 nm by seed‐mediated growth, with 17 nm Pd icosahedra serving as seeds. The multiply twinned Pd icosahedra could grow into larger sizes, and their shape and multiply twinned structure were preserved. Thanks to the presence of twin defects, the Pd icosahedra showed a catalytic current density towards formic‐acid oxidation that was 1.9 and 11.6 times higher than that of single‐crystal Pd octahedra, which were also fully covered by {111} facets, and commercial Pd/C, respectively.
Biomass‐Derived Chemicals: Synthesis of Biodegradable Surfactant Ether Molecules from Hydroxymethylfurfural
Authors: Arias Karen S. , Climent Maria J. , Corma Avelino , Iborra Sara 
Published: October 2013

AbstractA new class of biodegradable anionic surfactants with structures based on 5‐alkoxymethylfuroate was prepared starting from 5‐hydroxymethylfurfural (HMF), through a one‐pot–two‐steps process which involves the selective etherification of HMF with fatty alcohols using heterogeneous solid acid, followed by a highly selective oxidation of the formyl group with a gold catalyst. The etherification step was optimized using aluminosilicates as acid catalysts with different pore topologies (H‐Beta, HY, Mordenite, ZSM‐5, ITQ‐2, and MCM‐41), different active sites (Bronsted or Lewis) and different adsorption properties. It was shown that highly hydrophobic defect‐free H‐Beta zeolites with Si/Al ratios higher than 25 are excellent acid catalysts to perform the selective etherification of HMF with fatty alcohols, avoiding the competitive self‐etherification of HMF. Moreover, the 5‐alkoxymethylfurfural derivatives obtained can be selectively oxidized to the corresponding furoic salts in excellent yield using Au/CeO2 as catalyst and air as oxidant, at moderated temperatures. Both H‐Beta zeolite and Au/CeO2 could be reused several times without loss of activity.
Angular Distribution Analysis of Nitrogen Ions in a Low Energy Dense Plasma Focus Device
Authors: Sohrabi M. , Habibi M. , Yousefi H.R. , Roshani G.H. 
Published: October 2013

AbstractAngular distribution of nitrogen ions from a 4 kJ plasma focus device (PFD), as obtained by two detection methods was studied. The results obtained with two methods including consisting of (i) polycarbonate (PC) detectors (1 mm thick with about 15 cm diameter large etchable area) using electrochemical etching (ECE) at 50 Hz and 48 kV cm–1 field strenth and (ii) an array of five Faraday cups (FC) are analyzed, compared and discussed in this paper. The results obtained by the two detectors are quite different. A new concept is proposed in this paper for the ring‐shaped angular distribution of ions. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of Second Nonthermal Ion on the Characteristics of Dust Acoustic Solitary Waves in a Magnetized Dusty Plasma with Variable Dust Charge
Authors: Dezfuly S. Gh. , Dorranian D. 
Published: October 2013

AbstractThe nonlinear dust acoustic solitary waves in a magnetized dusty plasma with nonthermal ions and variable dust electric charge is studied analytically. Using reductive perturbation method the Zakharov‐Kuznetsov (ZK) equation is derived and effect of nonthermal coefficient, external magnetic field, and variable dust electric charge on the amplitude and width of soliton in dusty plasma is investigated. With increasing the rate of dust charge variation with respect of plasma potential, the amplitude of generated solitary waves in magnetized dusty plasma increases to a constant magnitude while its width decreases. Increasing the nonthermal ions coefficient leads to a noticeable decrease in the amplitude of solitons while the width of soliton increases. The amplitude of generated solitary waves in such a dusty plasma is independent of applied external magnetic field but we will have more localized solitons with increasing the external magnetic field strength. It is found that solitons are strongly influenced by the direction of external magnetic field. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Price‐based interference management in dense femtocell systems
Authors: Wang Xiaocheng , Han Qiaoni , Guan Xinping , Ma Kai 
Published: October 2013

SUMMARYFemtocell technology has been drawing considerable attention as a cost‐effective means of improving cellular coverage and capacity. However, under co‐channel deployment, femtocell system in dense environment may incur high uplink interference to existing macrocells and experiences strong inter‐cell interference at the same time. To manage the uplink interference to macrocell, as well as the inter‐cell interference, this paper proposes a price‐based uplink interference management scheme for dense femtocell systems. Specifically, on the one hand, to guarantee the macrocell users' quality of service, the macrocell base station prices the interference from femtocell users (FUEs) subject to a maximum tolerable interference power constraint. On the other hand, the inter‐cell interference is also taken into consideration. Moreover, a Stackelberg game model is adopted to jointly study the utility maximization of the macrocell base station and FUEs. Then, in order to reduce the amount of information exchange, we design a distributed power allocation algorithm for FUEs. In addition, admission control is adopted to protect the active FUEs' performance. Numerical results show that the price‐based interference management scheme is effective. Meanwhile, it is shown that the distributed power allocation combined with admission control is capable of robustly protecting the performance of all the active FUEs. Copyright © 2013 John Wiley & Sons, Ltd.
Using data mining approaches to identify voice over IP spam
Authors: Su Ming‐Yang , Tsai Chen‐Han 
Published: October 2013

SUMMARYWith its rapid growth in popularity and attendant personal and commercial use of voice over Internet protocol (VoIP), spam over VoIP has emerged as a significant problem. In this paper, we first applied genetic algorithms to weight predetermined features of VoIP calls. Based on the weighting technique, we then proposed a mechanism for the online prevention of VoIP spam by the k‐nearest neighbor classification. Differing from the traditional k‐nearest neighbor algorithm, this paper used genetic algorithms to weight features to reflect the different degree of importance of each feature. VoIP is a real‐time communication service, as compared to off‐line e‐mail, and VoIP spam is also known as Spam over Internet telephony (SPIT). The system proposed in this paper has been named PSPIT that denotes Prevention of SPIT. Once spam is identified, the proposed PSPIT immediately updates the built‐in blacklist on the Session Initiation Protocol (SIP) server to block that specific user from sending SPIT again. The n‐fold cross‐validation was applied to evaluate PSPIT for unknown SPIT detection; in the case of n = 2, the best overall accuracy was 94.7%, whereas in the case of n = 4, the best overall accuracy was 93.1%. Copyright © 2013 John Wiley & Sons, Ltd.
Postsynaptic assembly: A role for Wnt signaling
Authors: Stamatakou Eleanna , Salinas Patricia C. 
Published: October 2013

ABSTRACTSynapse formation requires the coordinated formation of the presynaptic terminal, containing the machinery for neurotransmitter release, and the postsynaptic side that possesses the machinery for neurotransmitter reception. For coordinated pre‐ and postsynaptic assembly signals across the synapse are required. Wnt secreted proteins are well‐known synaptogenic factors that promote the recruitment of presynaptic components in diverse organisms. However, recent studies demonstrate that Wnts act directly onto the postsynaptic side at both central and peripheral synapses to promote postsynaptic development and synaptic strength. This review focuses on the role of Wnts in postsynaptic development at central synapses and the neuromuscular junction. © 2013 The Authors. Developmental Neurobiology Published by Wiley Periodicals, Inc. Develop Neurobiol 74: 818–827, 2014
Consequences of variation in foraging success among predators on numerical response
Authors: Okuyama Toshinori 
Published: October 2013

AbstractThe relationship between foraging success and reproduction is commonly assumed to be linear in theoretical investigations. Although the exact relationship (e.g., linear or nonlinear) does not influence qualitative conclusions of models under some assumptions, an inclusion of individual behavioral variation can make it otherwise due to Jensen's inequality. In particular, a mechanism that stabilizes food web dynamics is generated when two conditions are satisfied: (1) the reproduction of predators experiences diminishing returns from foraging success (i.e., concave down relationship between foraging success and reproduction) and (2) foraging success variation among predator individuals increases with the predator density. However, empirical results that confirm these conditions are scarce. This study describes the mechanism as a hypothesis for stability and discusses some important considerations for empirical verifications of the mechanism.
Synthesis of Surface‐Functionalized Titania Particles with Organophosphorus Coupling Agents by Reactive Milling
Authors: Fischer Annika , Ney Christoph , Kickelbick Guido 
Published: October 2013

AbstractWe describe a top‐down approach for the synthesis of metal oxide particles with simultaneous surface modification. Functionalized titania particles were obtained by reactive milling together with phenylphosphonic acid in a high‐energy planetary ball mill. This process was accompanied by a tribochemical phase transition from the starting material anatase to the thermodynamically more stable rutile and a high‐pressure modification of titania, which was influenced by the presence of the coupling agent. The obtained products were characterized by X‐ray powder diffraction, IR and X‐ray fluorescence spectroscopy, thermal and elemental analysis as well as by scanning electron microscopy. The analysis showed final particle sizes of 100 to 300 nm, depending on the milling time and speed (rpm). Furthermore, the prepared particles showed a high degree of surface coverage with organophosphorus coupling agent, up to 1.4 mmol per gram. Coordination of the coupling agent to the surface resulted in a stabilization of the high‐pressure phase.
Zinc Thiocarboxylate Complexes as Precursors for Zinc Sulfide Nanoparticles under Aerobic Conditions
Authors: Vallejo‐Sánchez Daniel , Beobide Garikoitz , Castillo Oscar , Lanchas Mónica 
Published: October 2013

AbstractSix new compounds with the formula [Zn(SCOR)2(N–N)] [R = –CH3 (TAc), –C6H5 (TBn); N–N = 2,2′‐bipyridine (BPY), 1,10‐phenanthroline (PHEN), 1,2‐bis(4‐pyridyl)ethylene (BPE), neocuproine (NEO)] have been obtained by the reaction of Zn(CH3COO)2·2H2O with the corresponding pyridine derivative and thiocarboxylate in methanol in the ratio Zn/SCOR/N–N = 1:2:1. In all compounds, the metal atom is bonded to sulfur atoms of two thiocarboxylato ligands and to two nitrogen atoms from one pyridine derivative imposing a distorted‐tetrahedral geometry. The use of chelating dipyridine ligands leads to discrete monomeric entities in compounds [Zn(TAc)2(BPY)] (1), [Zn(TBn)2(BPY)] (2), [Zn(TAc)2(NEO)] (3), and [Zn(TBn)2(PHEN)] (4). On the contrary, the bridging capability of the dipyridine BPE ligand gives rise to the polymeric chains observed in compounds [Zn(TAc)2(μ‐BPE)] (5) and [Zn(TBn)2(μ‐BPE)] (6). The occurrence of Zn···O weak interactions is rationalized on the basis of the νC=O shift and continuous shape measurements. Additionally, the present work demonstrates how ZnS nanoparticles can be obtained by dry thermolysis of the prepared thiocarboxylate complexes under aerobic conditions and moderate temperatures (300 °C). The analysis of the X‐ray diffraction pattern and SEM/TEM images reveals the presence of ZnS crystallites below 10 nm. The influence of the N‐heterocycle and thiocarboxylato ligands on the crystalline phase (blende or wurtzite), size, and purity of the resulting zinc sulfide nanoparticles is discussed.
Transformation of the [MnII2MnIII2(hmp)6]4+ Core into [CoIII2MnII2(hmp)6]4+ in the Reaction of the [Mn4(hmp)6(NO3)2(H2O)2] Cluster with [CoX4]2– (X = Cl, Br)
Authors: Kushch Lyudmila A. , Yagubskii Eduard B. , Simonov Sergey V. , Shibaeva Rimma P. , Suturina Elizaveta A. , Gritsan Nina P. , Sadakov Andrei V. , Sulimenkov Il'ya V. 
Published: October 2013

AbstractThe reactions of [Mn4(hmp)6(NO3)2(H2O)2](ClO4)2 with (Bu4N)2[CoX4] (X = Cl, Br) in CH3CN have been studied and the new heterometallic tetranuclear clusters [CoIII2MnII2(hmp)6Cl2(CH3CN)2]MnIICl4·3CH3CN and [CoIII2MnII2(hmp)6Br2(CH3CN)2]MnIIBr4·4CH3CN have been synthesized and characterized by TGA, electrospray ionization mass spectrometry, single‐crystal X‐ray diffraction, and magnetic measurements. The magnetic properties of the heterometallic clusters were analyzed by DFT and ab initio calculations.
Oxidation of Dodecanoate Intercalated Iron(II)–Iron(III) Layered Double Hydroxide to Form 2D Iron(III) (Hydr)oxide Layers
Authors: Huang Li‐Zhi , Ayala‐Luis Karina B. , Fang Liping , Dalby Kim N. , Kasama Takeshi , Bender Koch Christian , Hansen Hans Christian B. 
Published: October 2013

AbstractA planar trioctahedral iron(II)–iron(III) hydroxide (green rust, GR) intercalated with dodecanoate (GRC12) has been oxidized by dioxygen to produce the corresponding planar iron(III) (hydr)oxide. The formulae of GRC12 and the final iron(III) product (oxGRC12) were determined to be FeII2.00FeIII1.00(OH)5.31(C12H23O2)0.66(SO4)0.51 and FeIII3O2.18(OH)3.13(C12H23O2)0.56(SO4)0.47, respectively. oxGRC12 has the same planar layer structure as GRC12, as revealed by identical powder X‐ray diffraction patterns. The electrostatic interactions between the interlayer dodecanoate (C12) anions and the iron hydroxide planar layer were preserved during the oxidation, as shown by FTIR spectroscopy. The high positive charge in the hydroxide layer produced by the oxidation of iron(II) to iron(III) is partially compensated by the deprotonation of hydroxy groups, as shown by X‐ray photoelectron spectroscopy. The Mössbauer quadrupole splitting of the iron(III) doublet increased on oxidation of GRC12, which has been attributed to the distortion of the octahedral sites caused by deprotonation and changes in the coordination site geometry. oxGRC12 is stable in air for more than 2 years. The van der Waals interactions between the alkyl chains of the intercalated dodecanoate anions play a crucial role in stabilizing the structure and hindering the collapse of the iron(II)–iron(III) (hydr)oxide structure during oxidation. This is the first report describing the formation of a stable planar layered octahedral iron(III) (hydr)oxide. oxGRC12 shows promise as a sorbent and host for hydrophobic reagents, and as a possible source of single planar layers of iron(III) (hydr)oxide.
Crystal Structure and Enhanced Piezoelectric Properties of Scandium and Bismuth‐Excess Modified Aurivillius Oxides, Na0.5–xBi2.5+xNb2–xScxO9
Authors: Long Changbai , Fan Huiqing , Li Mengmeng , Li Qiang 
Published: October 2013

AbstractAurivillius piezoelectrics, Bi–Sc modified Na0.5–xBi2.5+xNb2–xScxO9 (x = 0.05 and 0.1) and Na‐deficient and Bi‐enriched Na0.5–xBi2.5+xNb2O9 (x = 0.05, 0.1, and 0.2), were prepared by using a solid‐state reaction process. The Rietveld refinement verified that Sc3+ and excess Bi3+ were incorporated into the layered perovskite structure and that they occupied the B and A sites, respectively. The Na0.45Bi2.55Nb1.95Sc0.05O9 [0.05(BiSc)‐modified] crystallized in the orthorhombic space group A21am [a = 5.49853(9) Å, b = 5.45976(9) Å, c = 24.98351(29) Å, and V = 750.021(20) Å3; Z = 4] at room temperature. The A‐site Bi3+ donor substitution induced no obvious increase in the Curie point (Tc), but a further Sc3+ modification at the B site gave rise to a significant increase in Tc. The movements of non‐180° domains contributed to the piezoelectric activities of the Bi‐excess polycrystalline materials, whereas the excellent piezoelectric properties of the Bi–Sc‐modified polycrystalline materials mostly originated from intrinsic lattice contributions, which are due to their single‐180°‐domain‐wall structures. The Na0.45Bi2.55Nb1.95Sc0.05O9 [0.05(BiSc)‐modified] polycrystalline materials have a high Tc of 811 °C and a high piezoelectric activity (d33) of 28 pC/N; interestingly, its d33 was very stable against temperature.