bluuebunny/crossref_metadata_2025_split huggingface dataset:
Drag force of intermediate Reynolds number flow past mono‐ and bidisperse arrays of spheres
Authors: Beetstra R. , van der Hoef M. A. , Kuipers J. A. M. 
Published: January 2007

AbstractExtensive lattice‐Boltzmann simulations were performed to obtain the drag force for random arrays of monodisperse and bidisperse spheres. For the monodisperse systems, 35 different combinations of the Reynolds number Re (up to Re = 1,000) and packing fraction ϕ were studied, whereas for the bidisperse systems we also varied the diameter ratio (from 1:1.5 to 1:4) and composition, which brings the total number of different systems that we considered to 150. For monodisperse systems, the data was found to be markedly different from the Ergun equation and consistent with a correlation, based on similar type of simulations up to Re = 120. For bidisperse systems, it was found that the correction of the monodisperse drag force for bidispersity, which was derived for the limit Re = 0, also applies for higher‐Reynolds numbers. On the basis of the data, a new drag law is suggested for general polydisperse systems, which is on average within 10% of the simulation data for Reynolds numbers up to 1,000, and diameter ratios up to 1:4. © 2007 American Institute of Chemical Engineers AIChE J, 2007.
The instructive redox behaviour of 4‐ferrocenylcatechol on nanocrystalline titanium dioxide electrodes
Authors: Maharaj Felicia J. D. , McDonagh Andrew M. , Colbran Stephen B. 
Published: January 2007

AbstractAn investigation into the redox behaviour of 4‐ferrocenylcatechol bound to nanocrystalline TiO2 electrodes identified a limitation to the use of catechol as an electron‐transfer facilitating anchoring group. 4‐Ferrocenylcatechol was adsorbed to transparent nanocrystalline TiO2 electrodes. UV–visible spectra of the modified electrode were recorded in an acetonitrile‐electrolyte solution. At an applied potential of + 0.45 mV (vs Ag/AgCl/Cl−) the ferrocenyl group oxidized to the ferrocenium cation and the catecholate group oxidized to the benzoquinone form. Subsequent application of a potential of 0 V reduced the ferrocenium to ferrocene but, owing to the irreversibility of the catechol oxidation in aprotic solvents, benzoquinone is not reduced to catecholate and subsequently desorbs and is lost due into solution. Electrochromic switching of the ferrocenyl electrochromophore on TiO2 with aprotic electrolyte is, therefore, irreversible. Copyright © 2006 John Wiley & Sons, Ltd.
Replicated alternatives and the role of confusion, chasing, and regret in decisions from experience
Authors: Ert Eyal , Erev Ido 
Published: January 2007

AbstractThe current paper explores choice among alternatives that can be classified into distinct classes. All the members of a particular class were ‘replicated alternatives’: they promised the same payoff distribution. Information to decision makers was limited to feedback concerning the realized (obtained and foregone) payoffs. Experiment 1 demonstrates that increasing the number of replicated alternatives creates confusion (which facilitates random choice) and changes the implications of the tendency to chase recent returns (i.e., select the alternative with the best recent outcomes). This effect, termed ‘confused chasing,’ facilitates risk seeking even when this behavior impairs expected earnings. Experiment 2 reveals that increasing the number of replicated alternatives can reduce (but does not eliminate) the tendency to underweight rare events. Experiment 3 shows that the relative importance of chasing and confusion is sensitive to the likelihood of realizing lower payoffs than the forgone payoffs. The main results are summarized with a simple model assuming that payoff sensitivity decreases with experienced regret. Copyright © 2006 John Wiley & Sons, Ltd.
Simple Bisthiocarbonohydrazones as Sensitive, Selective, Colorimetric, and Switch‐On Fluorescent Chemosensors for Fluoride Anions
Authors: Han Feng , Bao Yuhui , Yang Zhigang , Fyles Thomas M. , Zhao Jianzhang , Peng Xiaojun , Fan Jiangli , Wu Yunkou , Sun Shiguo 
Published: January 2007

AbstractBisthiocarbonohydrazones are found to be a class of sensitive, selective, ratiometric, and colorimetric chemosensors for anions such as fluoride (F−) or acetate (Ac−). The sensitivities, or the binding constants of the sensors with anions, were found to be strongly dependent on the substituents appended on the π‐conjugation framework, the delocalization bridge CHN, the aromatic moiety, and the hetero atom in the CX group (X=O, S) of the sensors. Single‐crystal structures and 1H NMR titration analysis shows that the CHN moiety is a hydrogen‐bond donor, and it is proposed that an additional CH⋅⋅⋅F hydrogen bond is formed for the sensors in the presence F−. A sensor bearing anthracenyl groups is demonstrated as a switch‐on fluorescent chemosensor for F− and Ac−. The recognition of F− in acetonitrile (MeCN) by a sensor with nitrophenyl substituents is tolerant to MeOH (MeCN/MeOH=10:1, v/v) and water (MeCN/H2O=30:1, v/v); at these solvent ratios the absorption intensity of the sensor–F− complex solution at maximal absorption wavelength was attenuated to half of the original value in pure MeCN.
Well‐Defined Cationic Alkyl– and Alkoxide–Aluminum Complexes and Their Reactivity with ε‐Caprolactone and Lactides
Authors: Dagorne Samuel , Le Bideau Franck , Welter Richard , Bellemin‐Laponnaz Stéphane , Maisse‐François Aline 
Published: January 2007

AbstractWe describe the synthesis, structure, and reactivity of low‐coordinate Al–alkyl and –alkoxide cationic complexes incorporating the sterically bulky aminophenolate bidentate ligand 6‐(CH2NMe2)‐2‐CPh3‐4‐Me‐C6H2O− (N,O). These complexes are derived from the ionization of neutral dialkyl Al complexes (N,O)AlR2 (1 a, R=Me; 1 b, R=iBu), readily obtained by alkane elimination between AlR3 and the corresponding aminophenol ligand, with the alkyl abstracting reagents B(C6F5)3 and [Ph3C][B(C6F5)4]. The reactions of 1 a,b with B(C6F5)3 yield complicated mixtures or decomposition products, however the ionization of the Al–diisobutyl derivative 1 b with [Ph3C][B(C6F5)4] affords a stable four‐coordinate AlPhBr cationic adduct [(N,O)Al(iBu)(PhBr)]+ (3+), as deduced from elemental analysis data. Complex 3+ readily coordinates Lewis bases such as THF to form the corresponding adduct [(N,O)Al(iBu)(thf)]+ (4+), and also rapidly chain‐transfers with 1‐hexene to yield the three‐coordinate Al–hexyl cation [(N,O)Alhexyl]+ (5+). Both cations 3+ and 5+ slowly dimerize to form unprecedented organoaluminum dications [(N,O)AlR+]2 (3′++, R=iBu; 5′++, R=hexyl) as deduced from X‐ray crystallographic analysis. Cation 3+ reacts quickly with iPrOH to form a stable Lewis acid/base adduct [(N,O)Al(iBu)(HOiPr)]+ (6+), which constitutes the first X‐ray characterized adduct between an Al–alkyl complex and a simple ROH. The AlROH proton in 6+ is readily abstracted by NMe2Ph to form the neutral isopropoxide Al complex [(N,O)Al(iBu)(OiPr)] (7). Upon reaction with THF, cation 6+ undergoes an intramolecular proton transfer to yield the ammonium AlTHF complex [(η1‐HN,O)Al(iBu)(OiPr)(thf)] (8 b+), in which the aminophenolate is η1‐coordinated to the Al center. Cation 8 b+ can then be converted to the desired Al–alkoxide derivative [(N,O)Al(OiPr)(thf)]+ (10+), by an intramolecular protonolysis reaction, as confirmed by X‐ray crystallography. The synthesized Al–alkyl cations form robust four‐coordinate adducts in the presence of cyclic esters such as ε‐caprolactone and (d,l)‐lactide, but no insertion chemistry occurs, illustrating the poor ability of the AlR+ moiety to ring‐open. In contrast, the Al–alkoxide cation 10+ polymerizes ε‐caprolactone in a controlled manner with excellent activity, but is inactive in the polymerization of (d,l)‐lactide and L‐lactide. Control experiments with L‐lactide show that cation 10+ ring‐opens L‐lactide to yield a robust five‐coordinated Allactate cation [(N,O)Al(η2‐L‐lactate‐OiPr)(thf)]+ (13+), derived from a monoinsertion of L‐lactide into the AlOiPr bond of 10+, that does not further react. Cation 13+ may be regarded as a structurally characterized close mimic of the initial intermediate in the ring opening polymerization (ROP), of lactides by [{LX}M(OR)(L)] (where LX−=bidentate monoanionic ligand and L=labile ligand) metal complex initiators.
Osmium(II) and Ruthenium(II) Arene Maltolato Complexes: Rapid Hydrolysis and Nucleobase Binding
Authors: Peacock Anna F. A. , Melchart Michael , Deeth Robert J. , Habtemariam Abraha , Parsons Simon , Sadler Peter J. 
Published: January 2007

AbstractDensity functional calculations show that aquation of [Os(η6‐arene)(XY)Cl]n+ complexes is more facile for complexes in which XY=an anionic O,O‐chelated ligand compared to a neutral N,N‐chelated ligand, and the mechanism more dissociative in character. The O,O‐chelated XY=maltolato (mal) [M(η6‐p‐cym)(mal)Cl] complexes, in which p‐cym=p‐cymene, M=OsII (1) and RuII (2), were synthesised and the X‐ray crystal structures of 1 and 2⋅2 H2O determined. Their hydrolysis rates were rapid (too fast to follow by NMR spectroscopy). The aqua adduct of the OsII complex 1 was 1.6 pKa units more acidic than that of the RuII complex 2. Dynamic NMR studies suggested that O,O‐chelate ring opening occurs on a millisecond timescale in coordinating proton‐donor solvents, and loss of chelated mal in aqueous solution led to the formation of the hydroxo‐bridged dimers [(η6‐p‐cym)M(μ‐OH)3M(η6‐p‐cym)]+. The proportion of this dimer in solutions of the OsII complex 1 increased with dilution and it predominated at micromolar concentrations, even in the presence of 0.1 M NaCl (conditions close to those used for cytotoxicity testing). Although 9‐ethylguanine (9‐EtG) binds rapidly to OsII in 1 and more strongly (log K=4.4) than to RuII in 2 (log K=3.9), the OsII adduct [Os(η6‐p‐cym)(mal)(9EtG)]+ was unstable with respect to formation of the hydroxo‐bridged dimer at micromolar concentrations. Such insights into the aqueous solution chemistry of metal–arene complexes under biologically relevant conditions will aid the rational design of organometallic anticancer agents.
Shape‐Controlled Synthesis and Self‐Assembly of Hexagonal Covellite (CuS) Nanoplatelets
Authors: Du Weimin , Qian Xuefeng , Ma Xiaodong , Gong Qiang , Cao Hongliang , Yin Jie 
Published: January 2007

AbstractSingle‐crystalline, hexagonal covellite (CuS) nanoplatelets were successfully synthesized through a facile, inexpensive, reproducible, and improved solvothermal process in toluene at 120 °C for 24 h with hexadecylamine as a capping agent and copper acetate and carbon disulfide as precursors. These nanoplatelets are about 26±1.5 nm in diameter and 8±1.2 nm thick, and have a tendency to self‐assemble into pillarlike nanostructures with face‐to‐face stacks, raftlike nanostructures with side‐by‐side arrays, and stratiform nanostructures with layer‐by‐layer self‐assembly. The crystal shape, morphology, and crystallographic orientation of the covellite obtained were investigated by means of XRD, TEM, and high‐resolution TEM, and a potential self‐assembly mechanism was proposed.
Recent Developments in the Metal‐Catalyzed Reactions of Metallocarbenoids from Propargylic Esters
Authors: Marco‐Contelles José , Soriano Elena 
Published: January 2007

AbstractThe transition‐metal‐catalyzed intramolecular cycloisomerization of propargylic carboxylates provides functionalized bicyclo[n.1.0]enol esters in a very diastereoselective manner and, depending on the structure, with partial or complete transfer of chirality from enantiomerically pure precursors. The subsequent methanolysis gives bicyclo[n.1.0] ketones, hence resulting in a very efficient two‐step protocol for the syntheses of α,β‐unsaturated cyclopropyl ketones, key intermediates for the preparation of natural products. The results from mechanistic computational studies suggest that they probably proceed through cyclopropyl metallocarbenoids, formed by endo‐cyclopropanation, that undergo a 1,2‐acyl migration. Finally, the potential of the intermolecular reaction and the related pentannulation of propargylic esters bearing pendant aromatic rings are also discussed.
Minimal cycle basis of graph products for the force method of frame analysis
Authors: Kaveh A. , Mirzaie R. 
Published: January 2007

AbstractFor an efficient force method of frame analysis, the formation of localized self‐equilibrating systems is an important issue. Such systems can be constructed on minimal cycle basis of the graph model of the structure. In this paper, algorithms are presented for the formation of minimal cycle bases of graph products corresponding to sparse cycle adjacency matrices, leading to the formation of highly sparse flexibility matrices. The algorithms presented employ concepts from three graph products namely Cartesian, strong Cartesian and lexicographic products. Though the formulation for the first two products exist, however, efficient implementations are made in this paper. The formulation for the generation of minimal cycle basis is extended to the lexicographic product. Copyright © 2007 John Wiley & Sons, Ltd.
Increased immunofluorescence sensitivity using 532 nm laser excitation
Authors: Perfetto Stephen P. , Roederer Mario 
Published: January 2007

AbstractObjective:We evaluated the use of a high power, diode pulsed solid‐state laser emitting 532 nm light for immunofluorescence applications. We compared the sensitivity and utility of this laser with the standard 488 nm excitation.Methods:A flow cytometer was equipped with both a 488 nm and a 532 nm laser; fluorescence emissions from each laser were collected using the same filters and the same detector system. Cells or compensation beads (e.g. latex beads coated with anti‐κ antibodies) were stained with monoclonal antibodies conjugated to phycoerythrin (PE) as well as the PE tandem dyes TRPE, Cy5PE, Cy5.5PE, and Cy7PE. The sensitivity of detection of these reagents as well as those in heavily compensated channels was quantified by measuring the spreading error for a primary detector into a secondary detector.Results:Measurement of the fluorescence emission of PE and PE‐tandem dyes was considerably more sensitive when using 532 nm excitation (150 mW) as compared with 488 nm excitation (20 mW). In addition, as the absolute number of photoelectrons collected was greater, there was less measurement‐error‐induced spread into the compensated channels. As an example, when comparing the spreading error of PE labeled cells into the TRPE detector, the green laser was found to be 15‐fold more sensitive as compared with the blue laser. In addition, the blue laser produced more autofluoresent signal from cells as compared with the green laser. Together, these advantages of the 532 nm excitation line provides for a significantly improved detection of immunofluorescence staining. Published 2007 Wiley‐Liss, Inc.
Robust design of communication systems: The case of expedited forwarding of voice traffic in differentiated services networks
Authors: Yoon Hyoup‐Sang , Yum Bong‐Jin 
Published: January 2007

AbstractDesign of experiments (DOE) is gaining acceptance in the community of telecommunication researchers, especially during the past several years. In this paper, a state‐of‐the‐art review on the use of DOE in the field of communication networks is presented, and the need for introducing a systematic robust design methodology to network simulations or testbed experiments is identified in ensuring robust behaviours of a network against uncontrollable sources of variation. Then, the Taguchi robust design methodology is applied for optimizing the expedited forwarding (EF) of voice traffic in a differentiated services network, and its step‐by‐step procedures are described in detail. The experimental data are collected using the ns‐2 simulator, and the SN ratio, a robustness measure, is analysed to determine an optimal design condition for each performance characteristic. The analysis results show that ‘type of queue scheduling schemes’ is a major control factor for ensuring robust behaviours of one‐way delay and jitter while ‘EF queue size’ is for throughput and loss rate. Finally, a compromised optimal design condition is identified using a desirability function approach adapted to multi‐characteristic robust design problems. Copyright © 2007 John Wiley & Sons, Ltd.
Performance evaluation and damage assessment of steel frame buildings under main shock–aftershock earthquake sequences
Authors: Li Quanwang , Ellingwood Bruce R. 
Published: January 2007

AbstractStructures subjected to earthquake ground motions may be subjected to one or more aftershocks within a short period following the occurrence of the principal earthquake shock. Strong aftershocks have the potential to cause extensive structural damage, property losses and injuries to building occupants. This paper investigates the potential for aftershocks to cause additional damage to steel moment frame buildings, and provides a probabilistic description of structural damage states prior to and following those aftershocks. Statistics of structural response and damage states for steel frame buildings subjected to main shock–aftershock sequences are calculated using the enhanced uncoupled modal response history analysis (EUMRHA) method, a modification of an efficient and accurate method for predicting nonlinear response of frames. The frame connections are modelled by a moment–rotation relationship that takes brittle fracture of the connection welds into account. Damage accumulation is analysed in terms of a normalized ‘damage ratio’ and maximum inter‐storey drift. Simple probabilistic tools are proposed for purposes of rapid structural evaluation and condition assessment of damaged buildings. Copyright © 2007 John Wiley & Sons, Ltd.
The reflexive engineer: perceptions of integrated development
Authors: Robbins Peter T. 
Published: January 2007

AbstractThe professional ideology of engineers is said to be rooted in feelings of self‐importance and a belief in an ability to lead, based on qualities of technical expertise and rational decision‐making not held by the public at large. This paper outlines the views of another group of engineers, labelled ‘reflexive engineers’, having a much more integrated view of socio‐technical systems. Interviews were conducted with engineers working in the Global South in fields such as community water supply and sanitation. The paper aims to uncover how they make sense of the social and how they perceive factors shaping development practice. Copyright © 2007 John Wiley & Sons, Ltd.
Co‐evolutionary design for development: influences shaping engineering design and implementation in Nepal and the global village
Authors: Murcott Susan 
Published: January 2007

AbstractThis paper calls for a new generation of engineers, and the technologies they will invent and implement, to meet the basic human needs for security, broadly defined. The greatest threats to security for most people are not armed conflict but ‘common good’ social and environmental challenges. ‘Co‐evolutionary engineering design for development’ begins with a relationship among partners in the global village, informed by on‐the‐ground realities out of which culture/environment/location‐specific solutions emerge. This learning, iterative process among partners includes cooperation, local expertise, local resources and reliance on the global environment as a ‘lab’ for knowledge‐sharing and open‐source innovation. This article describes the conceptual framework of ‘co‐evolutionary design for development’ and takes the reader through the 10‐step cycle using, as a practical example, the design and implementation of an innovative arsenic and microbial remediation filter for households in rural Nepal. Copyright © 2007 John Wiley & Sons, Ltd.
Analysis of sodium adduct paeoniflorin, albiflorin and their derivatives by (+)ESI‐MSn, DFT calculations and computer‐aided mass spectrometry analysis program
Authors: Li Rui , Wang Xiaoling , Zhou Yan , Cai Min , Ding Lisheng 
Published: January 2007

AbstractIn order to analyze paeoniflorin, albiflorin and their derivatives (PADs) in Paeonia Lactiflora rapidly and effectively, (+)ESI‐MSn experiments were conducted, from which two diagnostic fragment patterns were acquired. Meanwhile, the dehydration ability of aglycones of PADs was obtained by calculating their activation energy using density functional theory, through which the unique dehydration phenomenon of benzoylalbiflorin, compared with benzoylpaeoniflorin, was interpreted. In addition, a computer‐aided mass spectrometry analysis program was developed to facilitate the analysis of the unknown compound by suggesting the possible structure of the analyte. Copyright © 2007 John Wiley & Sons, Ltd.
The Effect of Persistent TEMPO Radicals on the Gilch Polymerization
Authors: Wiesecke Jens , Rehahn Matthias 
Published: January 2007

AbstractThe mechanism of the Gilch polymerization leading to poly(p‐phenylene vinylenes) is still a matter of controversial discussion. Similar to some other research groups, we strongly favor a basically radical process. Moreover, we believe it is initiated by spontaneously formed diradicals. Here, we describe further experimental evidence which clearly supports the assumed initiation step: it is shown how the polymerization process is affected quantitatively when different amounts of 2,2,6,6‐tetramethylpiperidine‐N‐oxyl (TEMPO) are added as a scavenger. In full agreement with our expectations, the chain growth is either retarded or completely prevented, depending on the respective molar ratio of monomer and scavenger.magnified image
Pseudospectra, MUSIC, and dynamic wavelet neural network for damage detection of highrise buildings
Authors: Jiang Xiaomo , Adeli Hojjat 
Published: January 2007

AbstractA non‐parametric system identification‐based model is presented for damage detection of highrise building structures subjected to seismic excitations using the dynamic fuzzy wavelet neural network (WNN) model developed by the authors. The model does not require complete measurements of the dynamic responses of the whole structure. A large structure is divided into a series of sub‐structures around a few pre‐selected floors where sensors are placed and measurements are made. The new model balances the global and local influences of the training data and incorporates the imprecision existing in the sensor data effectively, thus resulting in fast training convergence and high accuracy. A new damage evaluation method is proposed based on a power density spectrum method, called pseudospectrum. The multiple signal classification (MUSIC) method is employed to compute the pseudospectrum from the structural response time series. The methodology is validated using the data obtained for a 38‐storey concrete test model. The results demonstrate the effectiveness of the WNN model together with the pseudospectrum method for damage detection of highrise buildings based on a small amount of sensed data. Copyright © 2007 John Wiley & Sons, Ltd.
Tension membranes modelled by curvi‐linear bicubic splines
Authors: Brew J. S. , Lewis W. J. 
Published: January 2007

AbstractOne of the unique features of tension membrane structures (used as architectural roofing forms) is that their shape under tension has to be determined through an iterative, computational process, known as form‐finding. This paper describes the spline analysis approach, which makes use of general curvilinear co‐ordinates in Cartesian system, to model surface‐stretched tension membranes and inflatable structures. Surface‐stretched membranes are characterized by zero pressure difference between their outer and inner surfaces, while inflatable structures derive their shape and surface tension from the respective pressure differences. Examples presented in the paper include applications to both types of tension membranes and, for inflatable structures, include the case where the pressure difference is non‐uniform. The method can be applied to finding natural forms of shell structures. Copyright © 2007 John Wiley & Sons, Ltd.