bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Solvent Polarity and Hydrogen Bonding on the Electronic Transition of Coumarin 120: A TDDFT Study
Authors: Zhao Wenwei , Pan Lu , Bian Wensheng , Wang Jianping
Published: July 2008

The characteristics of the electronic transition energy of Coumarin 120 (C120) and its H‐bonded complexes in various solvents have been examined by time‐dependent density functional theory (TDDFT) in combination with a polarizable continuum solvent model (PCM). Molecular structures of C120 and its H‐bonded complexes are optimized with the B3LYP method in PCM solution, and the dihedral angle H14N13C7H15 is dependent on solvent polarity and the type of H‐bond. A linear correlation of the absorption maximum of C120 with the solvent polarity function is revealed with the PCM model for all solvents except DMSO. The experimental absorption maximum of C120 in nine solvents is well described by a PCM–TDDFT scheme augmented with explicit inclusion of a few H‐bonded solvent molecules, and quantitative agreement between our calculated results and experimental measurements is obtained with an average error of less than 2 nm. H‐bonding at three different sites shifts the absorption wavelength of C120 either to the blue or to the red, that is, a significant role is played by solvent molecules in the first solvation shell in determining the electronic transition energy of C120. The dependence on the H‐bonding site and solvent polarity is examined by using the Kamlet–Taft equation for solvatochromism.
Post‐Deposition Opal Evolution
Authors: Popa Iulian , Marlow Frank
Published: July 2008

The formation of artificial opal films consists of wet opal deposition, drying, and possible transformations in the dry state. The processes after deposition, before the crystals lattice reaches its final equilibrium state, are studied herein. We follow the time evolution of the optical transmission spectra for polystyrene opals with different thicknesses. The evolution of the spectra shows pronounced changes in the Bragg peak position, width and height, as well as changes in the background and, in the beginning of the process, a band related to residual water in the sample. Therefore, a wet and a dry phase can be distinguished in the opal transformations. They are all connected to shrinkage and we associate one of them with a possible new sintering mechanism.
Structure of Pyridazine in the S1 State: Experiment and Theory
Authors: Ahn Doo‐Sik , Choi Kyo‐Won , Baek Sun Jong , Choi Young S. , Lee Sungyul , Choi Heechol , Baeck Kyoung Koo , Kim Sang Kyu
Published: July 2008

The molecular structure of pyridazine in the first electronically excited state (S1) is deduced from the combined use of resonance‐enhanced two‐photon ionization and mass‐analyzed threshold ionization spectroscopic methods. The equation‐of‐motion coupled‐cluster single and double (EOM–CCSD) calculation gives the distorted planar geometry for the most stable structure of the S1 pyridazine. The symmetry constraint of C2v is relaxed to that of Cs, and consequently many in‐plane vibrational modes are found to be optically active in both S1–S0 and D0–S1 excitation spectra, being appropriately assigned from the comparison of their frequencies with ab initio values. This indicates that the S1–S0 excitation is partially localized, and provides an alternative explanation for the long‐standing spectroscopic puzzle in S1 pyridazine.
Application of Static Charge Transfer within an Ionic‐Liquid Force Field and Its Effect on Structure and Dynamics
Authors: Youngs Tristan G. A. , Hardacre Christopher
Published: July 2008

The effects of linear scaling of the atomic charges of a reference potential on the structure, dynamics, and energetics of the ionic liquid 1,3‐dimethylimidazolium chloride are investigated. Diffusion coefficients that span over four orders of magnitude are observed between the original model and a scaled model in which the ionic charges are ±0.5 e. While the three‐dimensional structure of the liquid is less affected, the partial radial distribution functions change markedly—with the positive result that for ionic charges of ±0.7 e, an excellent agreement is observed with ab initio molecular dynamics data. Cohesive energy densities calculated from these partial‐charge models are also in better agreement with those calculated from the ab initio data. We postulate that ionic‐liquid models in which the ionic charges are assumed to be ±1 e overestimate the intermolecular attractions between ions, which results in overstructuring, slow dynamics, and increased cohesive energy densities. The use of scaled‐charge sets may be of benefit in the simulation of these systems—especially when looking at properties beyond liquid structure—thus providing an alternative to computationally expensive polarisable force fields.
Photodissociation Spectroscopy of CD3I+ Generated by Mass‐Analyzed Threshold Ionization for Structure Determination
Authors: Bae Yong Jin , Kim Myung Soo
Published: July 2008

A method is devised better to resolve the subbands of the ground vibronic band in the mass‐analyzed threshold ionization (MATI) spectrum of CD3I. By selective photodissociation of CD3I+ in these subbands, high‐resolution spectra for the Ã2A1←${{\bf{\tilde X}}}$2E3/2 transition are recorded. Spectral analysis confirms our previous suggestion that these subbands are due to cations in different rotational K states; this demonstrates the capability of MATI to generate rovibronically selected ion beams. By using the rotational constants of CH3I+ and CD3I+ obtained by spectral analysis, the zero‐point‐level geometries of the cations in the ${{\bf{\tilde X}}}$2E3/2 and Ã2A1 states are determined. To the best of our knowledge, this is the first time that the capability of MATI–PD to determine the geometry of a gas‐phase polyatomic cation in an excited electronic state is demonstrated.
Determination of the Degree of Charge‐Transfer Contributions to Surface‐Enhanced Raman Spectroscopy
Authors: Chenal Cat , Birke Ronald L. , Lombardi John R.
Published: July 2008

We explore the application of a previously suggested formula for determining the degree of charge transfer in surface‐enhanced Raman scattering (SERS). SERS is often described as a phenomenon which obtains its enhancement from three major sources, namely the surface plasmon resonance, charge‐transfer resonances as well as possible molecular resonances. At any chosen excitation wavelength, it is possible to obtain contributions from several sources and this has led to considerable confusion. The formula for the degree of charge transfer enables one to separate these effects, but it requires that spectra be obtained either at two or more different excitation wavelengths or as a function of applied potential. We apply this formula to several examples, which display rather large charge‐transfer contributions to the spectrum. These are p‐aminothiophenol (PATP), tetracyano‐ ethylene (TCNE) and piperidine. In PATP we can show that several lines of the same symmetry give the same degree of charge transfer. In TCNE we are able to identify the charge‐transfer transition, which contributes to the effect, and are able to independently determine the degree of charge transfer by wavenumber shifts. This enables a comparison of the two techniques of measurement. In piperidine, we present an example of molecule to metal charge transfer and show that our definition of charge transfer is independent of direction.
Boratabenzene Anions C5B(CN)6− and C5B(CF3)6− and the Superacidic Properties of their Conjugate Acids
Authors: Kütt Agnes , Koppel Ivar , Koppel Ilmar A. , Leito Ivo
Published: July 2008

Designing superacids: A computational study of protonated boratabenzenes and the gas‐phase acidity of their conjugate acids is presented. Conjugate acids of boratabenzenes substituted with CN or CF3 groups (see figure) are highly acidic species; the protonated hexacyanoboratabenzene and hexakis(trifluoromethyl)boratabenzene have computational gas‐phase acidities of 250.5 and 276.8 kcal mol−1, respectively.

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Growth, etching morphology and spectra of LiAlO2 crystal
Authors: Huang Taohua , Zhou Shengming , Teng Hao , Lin Hui , Wang Jun
Published: July 2008

γ‐LiAlO2 single crystal was successfully grown by Czochralski method. The crystal quality was characterized by X‐ray rocking curve and chemical etching. The effects of air‐annealing and vapor transport equilibration (VTE) on the crystal quality, etch pits and absorption spectra of LiAlO2 were also investigated in detail. The results show that the as‐grown crystal has very high quality with the full width at half maximum (FWHM) of 17.7‐22.6 arcsec. Dislocation density in the middle part of the crystal is as low as about 3.0×103 cm–2. The VTE‐treated slice has larger FWHM value, etch pits density and absorption coefficient as compared with those of untreated and air‐annealed slices, which indicates that the crystal quality became inferior after VTE treatment. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Flux growth of La‐doped lead zirconate stannate titanate antiferroelectric crystals
Authors: Wang Lin , Li Qiang , Zhang Yiling
Published: July 2008

Relaxor antiferroelectric single crystals lead lanthanum zirconate stannate titanate (PLZST) with the composition around the morphotropic phase boundary (MPB) have been grown by flux method using 50 wt% PbO‐PbF2‐B2O3 as a flux. The obtained crystals are light yellow in color. The XRD patterns revealed that the habitual faces of the obtained crystal are (001). The crystal morphology was studied and related to a layer growth mechanism controlled by two‐dimensional growth. The chemical composition of as‐grown crystal was analyzed by inductively coupled plasma atomic emission spectrometry (ICP), indicating a slight decrease of the amount of Ti compared to the starting materials. The result was verified by the XRD patterns with the phase transformation from the co‐existence of tetragonal and rhombohedra phases to the single tetragonal phase. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth aspects of barium oxalate monohydrate single crystals in gel medium
Authors: Raj A. Moses Ezhil , Jayanthi D. Deva , Jothy V. Bena , Jayachandran M. , Sanjeeviraja C.
Published: July 2008

Single crystals of barium oxalate monohydrate (BaC2O4.H2O, BOM) were grown in pure form by controlled diffusion of Ba2+ using the gel technique at different temperatures. Starting from aqueous Ba2+ chloride (BaCl2) and acetic acid (C2H2O4) in gel, this method offers a low‐cost and an easiest alternative to other preparation methods for the production of barium oxalate bulky single crystals. The optimal conditions for the growth of BOM crystals in silica gel were found by investigating different growth parameters such as gel pH, gel aging and crystallization temperature. Irrespective of all such crystallization environments, growth rate of the crystals were initially less and then exhibited supersaturation effect leading to non‐linearity. Gel aging and temperature has profound effect on nucleation density that resulted less number of crystals of maximum size in the gel matrix. Perfect single crystals were grown on gels of higher pH. The macropore morphology and porosity was controlled by changing age of the gel. It has been found that temperature has a fabulous effect in controlling the nucleation density by altering the supersaturation conditions for the formation of critical nuclei. The entire growth kinetics informed that the grown crystals were derived by the one dimensional diffusion controlled process. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth and characterization of Ytterbium doped KGd(WO4)2 single crystal
Authors: Samuel P. , Moorthy Babu S.
Published: July 2008

Single crystals of Ytterbium doped KGd(WO4)2 were grown by Top Seeded Solution Growth technique using K2WO4 as flux system. The growth parameters were optimised to get optically transparent crystals. Variation in the lattice parameters were observed in comparison to the pure KGd(WO4)2 crystals. The absorption spectra recorded for the Yb:KGW confirms the material suitability for diode pumped solid state lasers. The vibrational studies carried out using spontaneous Raman spectra indicate the strong anionic vibration of the material. PL spectra show the lasing channel of the laser active ions present. Stimulated Raman scattering analysis confirms the material as an efficient Raman laser material. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A theory for elastic properties of single crystals with microstructure and its application to diffusion induced segregation
Authors: Blesgen T.
Published: July 2008

In this article a general theory for elastically stressed single crystals in the presence of microstructure is presented and an explicit formula for the resulting non‐linear stored mechanical energy is obtained. The optimal microstructure under applied stress is characterised and the optimal laminates are identified in 2D. The analysis is based on a sharp lower estimate of the energy that relies on relaxation. The new theory is then used to extend existing models for diffusion induced segregation (DIS) in the case of (Zn,Fe)S single crystals. Numerical simulations based on finite elements are carried out and the results are compared with former computations of the homogeneous case. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis and optical properties of ZnO nanorods
Authors: Lang Jihui , Yang Jinghai , Li Changsheng , Yang Lili , Han Qiang , Zhang Yongjun , Wang Dandan , Gao Ming , Liu Xiaoyan
Published: July 2008

ZnO nanorods were prepared on the silicon (100) substrates using the chemical solution deposition method (CBD) without catalyst under a low temperature (90°C). The cool water was used to dissolve the mixture of zinc nitrate hexahydrate (Zn (NO3)2·6H2O) and methenamine (C6H12N4) in order to decrease the size of ZnO nanorods. From the X‐ray diffraction (XRD) results, it can be seen that the growth orientation of the as‐prepared ZnO nanorods was (002). Scanning electron microscopy (SEM) results illustrated that the nanorods had a hexagonal wurzite structure and average diameter of about 120nm. The average diameter of nanorods prepared by the cool water process was much smaller than that by the room‐temperature (RT) water process we always used. Photoluminescence (PL) measurements were also carried out. The result showed that a blue shift in UV emission band appeared in the PL spectrum of the sample grown with cool water process, which was mainly due to the reduction of tensile strain when the diameter of the ZnO nanorods decreased. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis, characterization and crystal structure of a novel 3‐D copper(II) polymer with bent N‐containing ligand
Authors: Wang Fumin
Published: July 2008

An exploration of the mixed‐ligand system under hydrothermal condition, has led to the isolation of a 3‐D novel framework {[Cu2(mp)L2)(H2O)2]·6H2O}n (1) (mp = benzene‐1,2,4,5‐ tetracarboxylate tetraanion, L = 4‐(5‐(pyridin‐4‐yl)‐1,3,4‐thiadiazol‐2yl)pyridine). Single‐crystal X‐ray analyses reveal that it crystallizes in the triclinic space group P‐1, a = 8.807(4) Å, b =11.139(6) Å, c = 11.291(5) Å, α=75.337(7), β = 73.584(5), γ= 66.795(5)°. The CuII ions are linked into an extended 2‐D grid net via mp molecules. Further these layers are united together through the bridging L to form a 3‐D structure, which exhibits a new 4‐connected topological network. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis, characterization and crystal structure of a novel 2D Cu(I) complex with flexible ligand
Authors: Liu Jianqiang , Wang Yaoyu , Zhang Weihong , Jin Juncheng , Zhang Mei , Shi Qizhen
Published: July 2008

An exploration of the Cu(I)‐L system under hydrothermal conditions, has led to the isolation of a novel framework [Cu(I)(L)]n (1) (L = bis(3,3‐dimethyl‐4,4‐dihydro‐1H‐pyrazol‐4‐yl)methane). Single‐crystal X‐ray analysis reveals that it crystallizes in the monoclinic, space group C2/c, a = 19.781(4) Å, b =11.026(3) Å, c = 16.339(4) Å, β = 127.186(3)°. The Cu ions are linked into an extended rainbow‐like chain via L molecules. Further, these adjacent chains are united together through hydrogen‐bonded interaction to a 2D layer. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Real time monitoring of BMP Smads transcriptional activity during mouse development
Authors: Monteiro Rui M. , de Sousa Lopes Susana M. Chuva , Bialecka Monika , de Boer Sophie , Zwijsen An , Mummery Christine L.
Published: July 2008

Bone morphogenetic protein (BMP) signaling is a key pathway in the patterning and development of organisms as diverse as fruit fly and humans. However, the determination of net BMP signaling, paramount to understanding organogenesis, is limited to the analysis of fixed material. We generated a transgenic mouse that reports the transcriptional response of BMP Smad activation by coupling a well established BMP response element (BRE), isolated from the Id1 promoter, to green fluorescent protein (BRE:gfp). We monitored BMP Smad transcriptional activity in fresh and fixed BRE:gfp embryos. GFP expression was observed where expected on the basis of known signaling sites, but also in specific cell populations in which BMP signaling had been implicated but not directly demonstrated. Deletion of Smad5 reduced GFP in vivo as expected. The BRE:gfp transgenic mice are a novel tool, which will facilitate the identification of specific BMP Smad responsive cell types and allow BMP Smad signaling to be monitored in real time, supporting studies in development and disease. genesis 46:335–346, 2008. © 2008 Wiley‐Liss, Inc.
Development of a gene‐trap vector with a highly sensitive fluorescent protein reporter system for expression profiling
Authors: Tanaka Tetsuya S. , Davey Ryan E. , Lan Qing , Zandstra Peter W. , Stanford William L.
Published: July 2008

Combining high‐content screening (HCS) with random gene‐trap mutagenesis could be a powerful tool to investigate transcriptional networks, cell signaling, chemical genetics, and developmental processes. However, a critical limitation has been poor quantification of reporter expression per cell. To overcome this hurdle, we generated a variety of Gtx‐based expression cassettes and re‐evaluated translational enhancement of arrayed Gtx segments in tandem by HCS. We then modified the cassette into a new polyA trap vector, which consists of a variant of yellow fluorescent protein, Venus, in combination with the Gtx segments. Expression of Venus was detected in about 60% of trapped genes assayed in embryonic stem cell (ESC) cultures, comparable to expression screening of LacZ‐based vectors. Furthermore, tetraploid aggregations using a clone encoding a gene‐trap insertion into Twist2 demonstrated identical spatiotemporal expression between Venus and Twist2. This highly sensitive reporter system is amenable to high‐throughput expression‐based real‐time HCS including single cell analyses. genesis 46:347–356, 2008. © 2008 Wiley‐Liss, Inc.
Deletion of GAD67 in dopamine receptor‐1 expressing cells causes specific motor deficits
Authors: Heusner Carrie L. , Beutler Lisa R. , Houser Carolyn R. , Palmiter Richard D.
Published: July 2008

The medium spiny neurons (MSNs), which comprise the direct and indirect output pathways from the striatum, use γ‐aminobutyric acid (GABA) as their major fact‐acting neurotransmitter. We generated mice carrying a conditional allele of the Gad1 gene, which encodes GAD67, one of the two enzymes responsible for GABA biosynthesis, and bred them to mice expressing Cre recombinase at the dopamine D1 receptor locus (Drd1a) to selectively reduce GABA synthesis in the direct output pathway from the striatum. We show that these mice are deficient in some types of motor skills, but normal for others, suggesting a differential role for GABA release from D1 receptor‐containing neurons. genesis 46:357–367, 2008. © 2008 Wiley‐Liss, Inc.
Synthesis of Manganese Oxide Hollow Urchins with a Reactive Template of Carbon Spheres
Authors: Wang Nan , Gao Yu , Gong Jian , Ma Xinyan , Zhang Xiaoli , Guo Yihang , Qu Lunyu
Published: July 2008

In this paper, a novel route to synthesize manganese oxide (MnO2) hollow urchins by a reactive template of carbon spheres is described. The formation process of the MnO2 hollow urchins and the mechanism for the removal of the carbon spheres are suggested. The results of scanning electron microscopy and transmission electron microscopy indicate that MnO2 shows a hollow‐urchin structure with an average diameter of 1.5 μm and with cavities that are about 250–500 nm in diameter. The X‐ray diffraction pattern indicates that the as‐prepared hollow urchins are γ‐MnO2. It has a highBrunauer–Emmett–Teller surface area of 110 m2 g–1 and a mesoporous structure. In addition, the magnetic properties of the γ‐MnO2 hollow urchins are investigated. This method opens a way to obtain different morphologies of metal oxides by changing the morphologies of the reactive carbon template. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Crystal Packing in Di‐(μ‐OH)‐ortho‐palladated Complexes – A DFT Insight into the Molecular Structure and Solid‐State Interactions
Authors: Pérez Jose , Espinosa Arturo , Galiana Jose M. , Pérez Eduardo , Serrano Jose L. , Cabeza Aurelio , Aranda Miguel A. G.
Published: July 2008

The crystal structures of [Pd(μ‐OH)(C∧N)]2[C∧N = phpy = 2‐(2‐pyridyl)phenyl (1), C∧N = bzq = 7,8‐benzoquinolin‐10‐yl (2)] have been elucidated by ab initio X‐ray powder diffraction methodology with monochromatic Cu‐Kα1radiation. The crystal structures have been refined by the Rietveld method. Both complexes exhibit a planar conformation in the solid state (which is the most frequent for this type of compounds as found in the Cambridge Structural Database). In compound1, three molecules are stacked in an overlappingparallel orientation. DFT calculations reveal that hydrogen bonds and Pd···Pd interactions are the reasons for the stability of this “trimer”. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Ferrocene‐Based Small Molecules for Multichannel Molecular Recognition of Cations and Anions
Authors: Molina Pedro , Tárraga Alberto , Caballero Antonio
Published: July 2008

This manuscript provides a summary of the relatively large body of research on the preparation and sensing properties of ferrocenes containing nitrogen functionalities, which have been mainly developed by our research group. After a general overview of the topic, selected recent advances in this field are described. In particular, new acyclic and cyclic structural motifs, in which the ferrocene unit is linked by unsaturated aza bridges (azadiene, azine, urea, guanidine, azaheterocycles) to a chromogenic or fluorescent signalling unit. Attention is drawn to the electrochemical and optical properties of these aza‐substituted ferrocene derivatives as well as their use in multichannel molecular recognition processes towards metal cations and anions.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Amberlite IRA900F as a Solid Fluoride Source for a Variety of Organic Transformations under Solvent‐Free Conditions
Authors: Fringuelli Francesco , Lanari Daniela , Pizzo Ferdinando , Vaccaro Luigi
Published: July 2008

We have reported that Amberlite IRA900F (Amb‐F) is an efficient metal‐free catalyst for the activation of Si–N and Si–O bonds and a mild base in a variety of organic transformations under solvent‐free conditions, such as the addition of TMSN3 to (E)‐2‐aryl‐1‐cyano‐1‐nitroethenes, nitriles, α,β‐unsaturated acids and their esters, and the addition of dimethylsilylketene acetal and ethyl nitroacetate to β‐nitrostyrenes.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Mechanisms of Brønsted Acid Catalyzed Additions of Phenols and Protected Amines to Olefins: A DFT Study
Authors: Li Xin , Ye Siyu , He Chuan , Yu Zhi‐Xiang
Published: July 2008

DFT calculations at the B3LYP/6‐31G(d) level were performed to understand the mechanism of the recentlydeveloped trifluoromethanesulfonic acid (TfOH) catalyzed intermolecular additions of phenols and protected amines to simple olefins. A novel mechanism involving a concerted, eight‐membered‐ring transition structure for the addition of the alcohol/amine to the alkene with TfOH as a catalyst was located. In the addition transition structure, the alkene substrate is protonated and has significant carbocation character. Calculations to rationalize the relative reactivities of the alcohols and amines, together with the regioselectivity of amide addition to the diene, were also conducted. Factors affecting isomerization of the alkene substrates in the alcohol addition process are discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Multicomponent Domino Reaction Promoted by Mg(ClO4)2: Highly Efficient Access to Functionalized 1,4‐Dihydropyridines
Authors: Bartoli Giuseppe , Bosco Marcella , Galzerano Patrizia , Giri Roberto , Mazzanti Andrea , Melchiorre Paolo , Sambri Letizia
Published: July 2008

An efficient, one‐pot multicomponent synthetic protocol toward substituted 1,4‐dihydropyridines from aromatic amines, β‐keto derivatives, and ethyl propiolate mediated by Mg(ClO4)2 is described. When ortho‐ or meta‐substituted arylamines are used, two conformational isomers are generated. An NMR spectroscopic study of the energy barrier involved in the interconversion of the isomers is reported.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Evaluation of an Intramolecular Approach for the Synthesis of the Elusive C58N2 Heterofullerene Family
Authors: von Delius Max , Hauke Frank , Hirsch Andreas
Published: July 2008

A new approach towards the synthesis of the elusive heterofullerene C58N2 is presented. The synthetic strategy is based on the intramolecular 1,3‐dipolar cycloaddition of a spacer‐linked azide to a monoazaheterofullerene (C59N) core. Since this cycloaddition can theoretically result in 16 different isomeric products, the design of the spacer moiety was based on extensive molecular modelling. Two fundamental synthetic routes towards suitably functionalized C59N derivatives were designed and carried out. Subsequent one‐pot experiments, each making use of the same conditions as had previously been employed for the introduction of the first nitrogen atom into the fullerene framework, were performed. Immediate analysis by FAB mass spectrometry indicated that up to 20 % of the submitted material indeed gave C58N2 species as fragmentation products. This result not only represents the first strategic synthesis of a C58N2 derivative, but also holds great promise for further efforts directed towards the preparative isolation of a member of the diaza[60]fullerene family. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Alkynyl Halides in Ruthenium(II)‐Catalyzed [2+2] Cycloadditions of Bicyclic Alkenes
Authors: Allen Anna , Villeneuve Karine , Cockburn Neil , Fatila Elisabeth , Riddell Nicole , Tam William
Published: July 2008

Ru‐catalyzed [2+2] cycloadditions between bicyclic alkenes and alkynyl halides were found to occur in moderate to good yields. The presence of the halide moiety greatly enhances the reactivity of the alkyne component in the cycloaddition and can be transformed into a variety of products that are difficult or impossible to obtain by direct cycloaddition. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Spatial dependence in the tails of air pollutant distributions: alternatives to the spatial correlogram
Authors: Arbia G. , Copetti M. , Lafratta G.
Published: July 2008

The study of the pollutants needs a better understanding of their extreme behaviours which could potentially cause adverse health effects. When analysing spatial dependence of the pollutant, the dependogram proposed by Arbia and Lafratta is preferred to the traditional correlogram used in the spatial statistics literature because it captures nonlinear relationships in the tails of the joint distributions and helps in detecting a pattern of spatial regularities. In this paper, we present a new method to estimate the spatial dependogram that uses univariate and bivariate threshold models. The method is applied to a set of hourly NO2data collected by seven monitoring stations in the city of Rome (Italy) during the years 2000 and 2001. Copyright © 2008 John Wiley & Sons, Ltd.
Large‐scale seismic tests of tall concrete bridge columns with precast segmental construction
Authors: Wang Jui‐Chen , Ou Yu‐Chen , Chang Kuo‐Chun , Lee George C.
Published: July 2008

Past experimental studies have shown that existing precast segmental concrete bridge columns possess unsatisfactory hysteretic energy dissipation capacity, which is an undesirable feature for applications in seismic regions. In this research, we propose new methods of precast segment construction for tall concrete bridge columns to enhance the columns' hysteretic energy dissipation capacity and lateral strength. This is accomplished by adding bonded mild steel reinforcing bars across the segment joints, strengthening the joint at the base of the column and increasing the height of the base segment (hinge segment). Four large‐scale column specimens were fabricated and tested with lateral cyclic loading in the laboratory. Each specimen consisted of a foundation and 9 or 10 precast column segments. Test results of specimens with the proposed design concepts showed ductile behavior and satisfactory hysteretic energy dissipation capacity. In addition to the experimental study, an analytical study using the finite element method was conducted to understand the bond conditions, strain contours and deformation patterns of the specimens tested. Good agreement was found between the experimental observations and the results of the calibrated analytical study. Copyright © 2008 John Wiley & Sons, Ltd.
Cyclic tests on a hybrid coupled wall utilizing a rocking mechanism
Authors: Hitaka Toko , Sakino Kenji
Published: July 2008

A new type of hybrid coupled wall system, consisting of rolled steel coupling beams, reinforced concrete (RC) wall piers, and concrete‐filled tube (CFT) short columns, is introduced. In this new system, the bases of the wall piers are connected to the base beams only through CFT short columns, unlike conventional coupled walls. Yield occurs in the coupling beams and the short columns; hence, in the RC wall piers, only minimum cracking appears. A total of four subassembly specimens, designed to fail in various collapse mechanisms, were cyclically loaded under constant axial force. A benchmark specimen showed ductile behavior with large energy dissipation until fracture occurred in the coupling beam. In the specimen designed to fail in shear in its CFT, substantial axial shortening was observed, but the overall behavior was ductile. Behavior of specimens with small amounts of section steel in the wall panel fringe, or with thin wall panels, also showed ductile behavior, but the strength and energy dissipation were significantly smaller than other two specimens. An analytical model was proposed for a frame analysis program using fiber elements to simulate elastic–plastic behavior of the system. Design methods to prevent shear failure of CFT and RC panels are suggested using the analytical and test results. Copyright © 2008 John Wiley & Sons, Ltd.
Comparison of the Eating Disorder Inventory (EDI) in the Netherlands, Austria and Italy
Authors: Waldherr Karin , Favaro Angela , Santonastaso Paolo , van Strien Tatjana , Rathner Günther
Published: July 2008

Objective

Comparison of scores of the Eating Disorder Inventory (EDI) in non‐clinical females aged 15–35 years (total n = 2402) in three European countries with North–South variation.

Methods

Participants were high school girls from the Netherlands (n = 642), Austria (n = 544) and Italy (n = 359), and college students from the Netherlands (n = 348), Austria (n = 114) and Italy (n = 395).

Results

Age‐dependent differences of EDI subscale scores were observed. Whereas in Dutch females weight and body shape concerns had a peak between 16 and 19 years, these concerns remained relatively constant in Italy and Austria. The Italian scores were significantly higher than the Dutch scores on almost all EDI subscales whereby effects were small or medium.

Conclusions

The scores may be influenced by socio‐cultural factors, cultural traits, culture‐specific social demands on young adults and differences in maturation between North and South Europe. National norms are necessary for different age, weight and sex groups. Copyright © 2008 John Wiley & Sons, Ltd and Eating Disorders Association.
Solutions to transmission constrained generation expansion planning using differential evolution
Authors: Kannan S. , Murugan P.
Published: July 2008

This paper describes the application of differential evolution (DE) technique for solving the transmission constrained generation expansion planning (TC‐GEP) problem. The TC‐GEP is a large scale and challenging problem for the decision makers (to decide upon site, capacity, type of fuel, etc.) as there exist a large number of combinations. The test system used is a modified IEEE‐30 bus test system with a planning horizon of 6 years. The results are compared and validated with dynamic programming (DP). Copyright © 2008 John Wiley & Sons, Ltd.
Adaptive MDPSK DS/CDMA receivers with performance analysis
Authors: Chen Jun‐Da , Ueng Fang‐Biau , Tsai Shang‐Chun , Chang Jui‐Chi , Chen Wei‐Chuan
Published: July 2008

For direct‐sequence code‐division multiple‐access (DS/CDMA) systems, the multiuser and multipath interferences are always present. When the demodulation is coherent, a coherent carrier reference must be generated prior to demodulation. The generation of coherent reference at low signal‐to‐interference‐and‐noise ratio (SINR) is difficult. In the downlink CDMA communications, numbers of active users transmit information simultaneously by different signature waveform. However, the multipath channel and multiple‐access interference (MAI) limit the system capacity. Adaptive single‐user receivers do not require knowledge of MAI parameters and need fewer computations. In this paper, we propose adaptive receivers with decision‐feedback differential detection (DF‐DD) and compare variations of the receiver structure proposed in Schrober's paper for noncoherent channels. In the absence of knowledge of the carrier phase, we derive the minimum mean square error (MMSE) of the proposed receivers to show that the performances of the proposed receivers with M‐ary differential phase‐shift keying (MDPSK) signals approach that of the coherent receiver with MPSK signal. Some simulation examples are given to demonstrate the effectiveness and compare the performances of the proposed adaptive receivers. Copyright © 2008 John Wiley & Sons, Ltd.
Hybrid turbulence simulation of spray impingement cooling: The effect of vortex motion on turbulent heat flux
Authors: Kondaraju S. , Lee J. S.
Published: July 2008

Spray impingement has been a major interest of researchers in the areas of spray cooling, internal combustion, fire suppression and spray cooling, etc. for a long time. Numerous studies have been done in the area of spray cooling. Spray cooling with phase change takes advantage of relatively large amounts of latent heat and is capable of removing high heat fluxes from the surface, which has generated the interest of many researchers. In this paper, the turbulent characteristics of vapor formed during the spray impingement are studied. Water and gasoline are used in the numerical analysis of the two‐phase spray impingement on a heated wall. Hybrid turbulence modeling was used for the analysis where the subgrid scale model was employed away from the wall and k–ε model was used near the wall. Gasoline, at 298 K, was sprayed on the heated wall, kept constant at 650 K. The surrounding temperature was maintained at 400 K at the start of the simulation. In case of water and gasoline at Reynolds number 2750, the heated wall was kept constant at 400 K and the surrounding temperature was maintained at 298 K at the start of the simulations. The nozzle diameter of 100µm was used for this study, with the nozzle plate spacing ratio at 10. The spray was impinged on the flat plate at angles of 0, 15, and 30°. Root mean‐squared velocities and turbulent heat flux were plotted in the water spray impingement for the different angles of impingement. The effect of turbulence on the heat transfer was observed. The effect of vortex motion on the turbulent heat flux values was analyzed using different Reynolds numbers of impingement and at different angles in case of gasoline. The turbulent heat flux attained the maximum values with high vortex formation. Upwash of fluid transported heat away from the wall, producing higher heat flux values in the region. Copyright © 2008 John Wiley & Sons, Ltd.
Numerical modeling of turbulent compound channel flow using the lattice Boltzmann method
Authors: Liu H. , Zhou J. G. , Burrows R.
Published: July 2008

The flow of water in a straight compound channel with prismatic cross section is investigated with a relatively new tool, the lattice Boltzmann method. The large eddy simulation model is added in the lattice Boltzmann model for nonlinear shallow water equations (LABSWETM) so that the turbulence, caused by lateral exchange of momentum in the shear layer between the main channel and floodplain, can be taken into account and modeled efficiently. To validate the numerical model, a symmetrical compound channel with trapezoidal main channel and flat floodplain is tested. Similar to most natural watercourses, the floodplain has higher roughness values than the main channel. Different relative depths,Dr(the ratio of the depth of flow on the floodplain to that in the main channel), are considered. The Reynolds number is set at 30 000 in the main channel. The lateral distributions of the longitudinal velocity, the boundary shear stress, the Reynolds stress and the apparent shear stress across the channel are obtained after the large eddy simulation is performed. The results of numerical simulations are compared with the available experiment data, which show that the LABSWETMis capable of modeling the features of flow turbulence in compound channels and is sufficiently accurate for practical applications in engineering. Copyright © 2008 John Wiley & Sons, Ltd.
Reduced‐order modelling of an adaptive mesh ocean model
Authors: Fang F. , Pain C. C. , Navon I. M. , Piggott M. D. , Gorman G. J. , Allison P. A. , Goddard A. J. H.
Published: July 2008

A novel proper orthogonal decomposition (POD) model has been developed for use with an advanced unstructured mesh finite‐element ocean model, the Imperial College Ocean Model (ICOM, described in detail below), which includes many recent developments in ocean modelling and numerical analysis. The advantages of the POD model developed here over existing POD approaches are the ability:

To increase accuracy when representing geostrophic balance (the balance between the Coriolis terms and the pressure gradient). This is achieved through the use of two sets of geostrophic basis functions where each one is calculated by basis functions for velocities u and v.

To speed up the POD simulation. To achieve this a new numerical technique is introduced, whereby a time‐dependent matrix in the discretized equation is rapidly constructed from a series of time‐independent matrices. This development imparts considerable efficiency gains over the often‐used alternative of calculating each finite element over the computational domain at each time level.

To use dynamically adaptive meshes in the above POD model.

Copyright © 2008 John Wiley & Sons, Ltd.
A stabilized mixed finite element method for the first‐order form of advection–diffusion equation
Authors: Masud Arif , Kwack JaeHyuk
Published: July 2008

This paper presents a stabilized mixed finite element method for the first‐order form of advection–diffusion equation. The new method is based on an additive split of the flux‐field into coarse‐ and fine‐scale components that systematically lead to coarse and fine‐scale variational formulations. Solution of the fine‐scale variational problem is mathematically embedded in the coarse‐scale problem and this yields the resulting method. A key feature of the method is that the characteristic length scale of the mesh does not appear explicitly in the definition of the stability parameter that emerges via the solution of the fine‐scale problem. The new method yields a family of equal‐ and unequal‐order elements that show stable response on structured and unstructured meshes for a variety of benchmark problems. Copyright © 2008 John Wiley & Sons, Ltd.
A high‐order Petrov–Galerkin finite element method for the classical Boussinesq wave model
Authors: Avilez‐Valente Paulo , Seabra‐Santos Fernando J.
Published: July 2008

A high‐order Petrov–Galerkin finite element scheme is presented to solve the one‐dimensional depth‐integrated classical Boussinesq equations for weakly non‐linear and weakly dispersive waves. Finite elements are used both in the space and the time domains. The shape functions are bilinear in space–time, whereas the weighting functions are linear in space and quadratic in time, with C0‐continuity. Dispersion correction and a highly selective dissipation mechanism are introduced through additional streamline upwind terms in the weighting functions. An implicit, conditionally stable, one‐step predictor–corrector time integration scheme results. The accuracy and stability of the non‐linear discrete equations are investigated by means of a local Taylor series expansion. A linear spectral analysis is used for the full characterization of the predictor–corrector inner iterations. Based on the order of the analytical terms of the Boussinesq model and on the order of the numerical discretization, it is concluded that the scheme is fourth‐order accurate in terms of phase velocity. The dissipation term is third order only affecting the shortest wavelengths. A numerical convergence analysis showed a second‐order convergence rate in terms of both element size and time step. Four numerical experiments are addressed and their results are compared with analytical solutions or experimental data available in the literature: the propagation of a solitary wave, the oscillation of a flat bottom closed basin, the oscillation of a non‐flat bottom closed basin, and the propagation of a periodic wave over a submerged bar. Copyright © 2008 John Wiley & Sons, Ltd.
A robust algorithm for computing fluid flows on highly non‐smooth staggered grids
Authors: Rabiee A. , Ziaei A. N. , Alishahi M. M. , Emdad H.
Published: July 2008

A new method for computing the fluid flow in complex geometries using highly non‐smooth and non‐orthogonal staggered grid is presented. In a context of the SIMPLE algorithm, pressure and physical tangential velocity components are used as dependent variables in momentum equations. To reduce the sensitivity of the curvature terms in response to coordinate line orientation change, these terms are exclusively computed using Cartesian velocity components in momentum equations. The method is then used to solve some fairly complicated 2‐D and 3‐D flow field using highly non‐smooth grids. The accuracy of results on rough grids (with sharp grid line orientation change and non‐uniformity) was found to be high and the agreement with previous experimental and numerical results was quite good. Copyright © 2008 John Wiley & Sons, Ltd.
Study of a staggered fourth‐order compact scheme for unsteady incompressible viscous flows
Authors: Knikker R.
Published: July 2008

The objective of this paper is the development and assessment of a fourth‐order compact scheme for unsteady incompressible viscous flows. A brief review of the main developments of compact and high‐order schemes for incompressible flows is given. A numerical method is then presented for the simulation of unsteady incompressible flows based on fourth‐order compact discretization with physical boundary conditions implemented directly into the scheme. The equations are discretized on a staggered Cartesian non‐uniform grid and preserve a form of kinetic energy in the inviscid limit when a skew‐symmetric form of the convective terms is used.

The accuracy and efficiency of the method are demonstrated in several inviscid and viscous flow problems. Results obtained with different combinations of second‐ and fourth‐order spatial discretizations and together with either the skew‐symmetric or divergence form of the convective term are compared. The performance of these schemes is further demonstrated by two challenging flow problems, linear instability in plane channel flow and a two‐dimensional dipole–wall interaction. Results show that the compact scheme is efficient and that the divergence and skew‐symmetric forms of the convective terms produce very similar results. In some but not all cases, a gain in accuracy and computational time is obtained with a high‐order discretization of only the convective and diffusive terms. Finally, the benefits of compact schemes with respect to second‐order schemes is discussed in the case of the fully developed turbulent channel flow. Copyright © 2008 John Wiley & Sons, Ltd.
Analysis of a consistency recovery method for the 1D convection–diffusion equation using linear finite elements
Authors: Nadukandi Prashanth , Oñate Eugenio , Garcia Julio
Published: July 2008

For residual‐based stabilization methods such as streamline‐upwind Petrov–Galerkin (SUPG) and finite calculus (FIC), the higher‐order derivatives of the residual that appear in the stabilization term vanish when simplicial elements are used. The sub‐grid scale method using orthogonal sub‐scales (OSS) attempts to recover the lost consistency by using a fine‐scale projected residual in the stabilization term. The FIC method may also be cast into an OSS form with very little manipulation using an auxiliary convective projection equation. This paper discusses the gain/loss by recovering the consistency of the discrete residual in the stabilization terms via the form that includes the convective projection (as in the OSS method). We present the von Neumann analysis of the FIC method with recovered consistency (FIC_RC) for the 1D convection–diffusion problem and we compare it with the standard Bubnov–Galerkin linear finite element method and FIC/SUPG methods. The transient analysis is done by examining the discrete dispersion relation of the stabilization methods. The spectral results for the semi‐discrete and fully discrete problem are presented with time integration done by the trapezoidal and second‐order backward differencing formula schemes. The effect of lumping the effective mass matrix T is considered relative to using a consistent form. The effect of refinement in space and time is also discussed. Finally, an optimal expression for the stabilization parameter for the FIC_RC method on a uniform grid and for the steady state is given and its performance in the transient mode is discussed. Copyright © 2008 John Wiley & Sons, Ltd.