bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sn20.5□3.5As22I8: A Largely Disordered Cationic Clathrate with a New Type of Superstructure and Abnormally Low Thermal Conductivity
Authors: Zaikina Julia V. , Kovnir Kirill A. , Sobolev Alexei V. , Presniakov Igor A. , Prots Yuri , Baitinger Michael , Schnelle Walter , Olenev Andrei V. , Lebedev Oleg I. , Van Tendeloo Gustaaf , Grin Yuri , Shevelkov Andrei V. 
Published: March 2007

AbstractSn20.5As22I8, a new cationic clathrate, has been prepared by using an ampoule technique. According to the X‐ray powder diffraction data, it crystallizes in the face‐centered cubic space group F23 or Fm$\bar 3$ with a unit‐cell parameter of a=22.1837(4) Å. Single‐crystal X‐ray data allowed solution of the crystal structure in the subcell with a unit‐cell parameter of a0=11.092(1) Å and the space group Pm$\bar 3$n (R=5.7 %). Sn20.5As22I8 (or Sn20.5□3.5As22I8, accounting for the vacancies in the framework) possesses the clathrate‐I type crystal structure, with iodine atoms occupying the cages of the cationic framework composed of tin and arsenic atoms. The crystal structure is strongly disordered. The main features are a random distribution of vacancies, and shifts of the tin and arsenic atoms away from their ideal positions. The coordination of the tin atoms has been confirmed by using 119Sn Mössbauer spectroscopy. Electron diffraction and high‐resolution electron microscopy (HREM) analyses have confirmed the presence of the superstructure ordering, which results in a doubling of the unit‐cell parameter and a change of the space group from Pm$\bar 3$n to either F23 or Fm$\bar 3$. Analysis of the crystal structure has led to the construction of four ordering models for the superstructure, which have been corroborated by HREM, and has also led to the identification of disordered regions originating from overlap of the different types of ordered domains. Sn20.5As22I8 is a diamagnetic semiconductor with an estimated band gap of 0.45 eV; it displays abnormally low thermal conductivity, with the room temperature value being just 0.5 W m−1 K−1.
Modification of Methylaluminoxane‐Activated ansa‐Zirconocene Catalysts with Triisobutylaluminum—Transformations of Reactive Cations Studied by NMR Spectroscopy
Authors: Babushkin Dmitrii E. , Brintzinger Hans H. 
Published: March 2007

AbstractWhen triisobutylaluminum (AliBu3) is added to solutions containing methylaluminoxane (MAO) and rac‐[Me2Si(ind)2ZrCl2] (ind: indenyl) in C6D6, NMR spectra show that methyl‐bridged mixed‐alkylaluminum dimers Al(μ‐Me)2Me4−xiBux predominate. These dimers react with MAO under partial transfer of isobutyl groups and induce a conversion of the initially prevailing cationic trimethylaluminum adduct rac‐[Me2Si(ind)2Zr(μ‐Me)2AlMe2+] to rac‐[Me2Si(ind)2Zr(μ‐Me)2AlMeiBu+] and rac‐[Me2Si(ind)2Zr(μ‐Me)2AliBu2+]. These species are unstable and release isobutene under formation of zirconocene hydrides.
Efficient automated assessment of genetic abnormalities detected by fluorescence in situ hybridization on brush cytology in a Barrett esophagus surveillance population
Authors: Rygiel Agnieszka M. , van Baal Jantine W. P. M. , Milano Francesca , Wang Kenneth K. , ten Kate Febo J. , Fockens Paul , Rosmolen Wilda D. , Bergman Jacques J. G. H. M. , Peppelenbosch Maikel P. , Krishnadath Kausilia K. 
Published: March 2007

AbstractBACKGROUND.Automated assessment of genetic abnormalities detected by fluorescence in situ hybridization (FISH) in brush cytology specimens from patients with Barrett esophagus (BE) may enhance the clinical applicability of this methodology. The objectives of this study were to validate a novel, automated, proprietary system (CytoVison SPOT AX) for the assessment of FISH abnormalities in BE brush cytology and, subsequently, to use this automated method for screening of a BE surveillance cohort.METHODS.FISH with DNA probes for chromosomes 9, 17, and Y, and for the 9p21 (p16), 17q11.2 (Her2/neu), and 17p13.1 (p53) loci was applied on brush cytology specimens from a surveillance cohort of 151 patients with BE. Validation of the automated system was performed by comparison of the automated FISH results with manual scores for the first 60 patients.RESULTS.There was 98% concordance between manual and automated FISH analysis with κ values from 0.49 to 1 for the different probes. The loss of 17p13.1 (p53) was observed in only 5% of patients with no dysplasia (ND) and in 9% of patients with low‐grade dysplasia (LGD) but increased to 46% in patients with high‐grade dysplasia (HGD) (P < .005; Fisher exact test). Chromosomes 9 and 17 were observed in 6% of patients with ND, in 21% of patients with LGD, and in 62% of patients with HGD (P < .05). Ten percent of patients with ND had loss of the Y chromosome, which increased to 27% in patients with HGD (P< .05). The amplification of 17q11.2 (Her2/neu) was detected in 62% of patients with HGD (P < .001).CONCLUSIONS.The current investigation indicated that the CytoVison SPOT AX is an objective, efficient system for the analysis of DNA‐FISH on BE brush cytology and is applicable for analyzing large populations of BE patients. In the current study cohort, the loss of 17p13.1 (p53), Y chromosome loss, and polysomy of chromosomes 17 and 9 were correlated with increasing grade of dysplasia in patients with BE. Cancer 2007. © 2007 American Cancer Society.
Chelating η6‐Arene‐η1‐carbene Ligands in Ruthenium Complexes
Authors: Özdemir Ismail , Demir Serpil , Çetinkaya Bekir , Toupet Loïc , Castarlenas Ricardo , Fischmeister Cédric , Dixneuf Pierre H. 
Published: March 2007

AbstractN‐Heterocyclic carbene (NHC) ruthenium complexes containing a chelating NHC‐η6‐arene ligand have been prepared and evaluated as precursors for ring opening metathesis polymerization (ROMP). The reaction of [RuCl2(p‐cymene)]2 with electron‐rich olefins of the bis(imidazolinylidene) type containing at least one arylmethyl‐N chain (aryl: 2,4,6‐trimethylphenyl, 3,4,5‐trimethoxyphenyl) selectively leads, upon heating, to ruthenium(II) complexes 2 containing a chelating bridged carbene η6‐arene ligand. The reaction of complexes containing an additional ROCH2CH2N group with AgOTf leads to ionic complexes 5 with a tridentate trifunctional carbene/arene/ether ligand. The X‐ray structure of[RuCl2{η1‐CN(CH2{η6‐C6H2Me3‐2,4,6})CH2CH2N(CH2{C6H2(OMe)3‐3,4,5})}] (2c) and that of the ionic ruthenium complex containing a trifunctional carbene/arene/ether ligand that provides ten electrons, [RuCl{η1‐CN(CH2{η6‐C6H2Me3‐2,4,6})CH2CH2N(CH2CH2OCH3)}][CF3SO3] (5e), have been determined. The precursors 2 in the presence of AgOTf and propargyl alcohol, in order to produce an allenylidene initiator, and complexes 5 in the presence of propargyl alcohol lead to ROMP of norbornene. It is shown that initial chloride abstraction is required and that the catalyst activity is increased by using mesityl–ruthenium precursors and coordinated branched ether complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Hydrogenation of a Trinuclear μ3‐Imido Complex of Ruthenium: Homolytic or Heterolytic H–H Bond Cleavage?
Authors: Kameo Hajime , Nakajima Yumiko , Suzuki Hiroharu 
Published: March 2007

AbstractTo elucidate the mode of hydrogen–hydrogen bond cleavage at transition metal sites that cooperate with a heteroatom, the hydrogenation of trinuclear μ3‐imido complex (Cp*Ru)3(μ3‐NH)(μ‐H)3 (Cp* = η5‐C5Me5) (1) with deuterium was carried out. The percentage of deuterium content in the amido ligand of (Cp*Ru)3(μ‐NH2)(μ‐H)4 (2), which was generated as an intermediate in the reaction of 1 with dihydrogen, proved that hydrogenation of 1 to 2 proceeded through homolytic cleavage of dihydrogen.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Novel Sorbicillin Derivatives with an Unprecedented Carbon Skeleton from the Sponge‐Derived Fungus Trichoderma Species
Authors: Neumann Kerstin , Abdel‐Lateff Ahmed , Wright Anthony D. , Kehraus Stefan , Krick Anja , König Gabriele M. 
Published: March 2007

AbstractChemical investigation of the fungus Trichoderma sp., isolated from the Caribbean sponge Agelas dispar led to four novel sorbicillinoid polyketide derivatives (1–4) with an unprecedented tricyclic ring system. The structures of all compounds, including the absolute configuration, were determined by interpretation of their spectroscopic data (1D and 2D NMR, CD, MS, UV and IR), and molecular modeling calculations. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Coupled hydrodynamic response of concrete gravity dams using finite and infinite elements
Authors: Saini S. S. , Bettess P. , Zienkiewicz O. C. 
Published: March 2007

AbstractThis paper presents the application of the finite element method for analysing the two‐dimensional response of reservoir‐dam systems subjected to horizontal ground motion. The interaction between the dam and the reservoir as well as the compressibility of water has been taken into account. The complete system has been considered to be composed of two substructures, namely the reservoir and the dam. To take into account the large extent of the reservoir, it has been idealized using specially developed infinite elements coupled with standard finite elements while the dam is represented using finite elements alone. Structural damping of the dam and radiation damping in the fluid phase have been accounted for in the analysis. It is concluded that the effect of radiation damping is considerable at high frequencies of excitation. The coupled response of the system is significantly large at and near the fundamental natural frequency of the system in comparison to the uncoupled responses. The method is computationally quite economical, capable of taking into account the arbitrary geometry of the system and is recommended for practical application. Further applications and extensions of the approach to three dimensional analyses are possible.
Response spectrum techniques for asymmetric buildings
Authors: Rutenberg Avigdor , Hsu Tzu‐I. , Tso W. K. 
Published: March 2007

AbstractA scheme is proposed to calculate the effect of torsion on each lateral load resisting element of asymmetrical buildings in the context of the response spectrum technique. The scheme consists of: (i) Obtain the modal shear and torque on the building by the response spectrum technique, (ii) Compute the total modal shear forces on each frame by resolving the modal shear and torque on the building according to principles of structural mechanics. The shears on each frame due to the lateral load effect and torsional effect are combined algebraically, (iii) Obtain the total shear force on each frame by combining the total modal shears on that frame in a root sum square manner.Since the proper phase relationship between the lateral load effect and torsional effect is accounted for on a modal basis, it is believed that the proposed scheme provides a more realistic load estimate on the frames than the conventional approach. An example of a simplified mono‐symmetrical frame structure is chosen to illustrate the accuracy of the proposed scheme, using dynamic time‐history analysis as a standard for comparison.
Soil‐structure interaction for tower structures
Authors: Warburton G. B. 
Published: March 2007

AbstractThe soil‐structure system is modelled as a uniform vertical beam, which terminates in a base or foundation mass; this mass is attached to the surface of an elastic half‐space. Using known force‐displacement relations for the coupled vibrations of a rigid disc on an elastic half‐space, the natural frequencies and response to a transverse harmonic force, applied at the tip of the beam, are determined through a continuum approach. Effectively the problem reduces to a beam with frequency‐dependent boundary conditions. A parametric study shows that changes in the three ratios, Young's modulus for the beam to that for the half‐space, the radius of the base mass to the length of the beam, L, and the second moment of area of the beam cross‐section/L4, cause large variations in the maximum response, which due to interaction can be considerably smaller or larger than that for a comparable fixed‐base cantilever beam. This dynamic behaviour can be explained by considering the variation of natural frequencies, mode shapes and modal damping factors with these ratios.A brief study of the response of the structure to a free‐field harmonic acceleration, applied at the soil‐structure interface, suggests that interaction depends upon material and geometric properties of the system, rather than on the nature of the excitation.
Dynamic interaction for idealized off‐shore structures
Authors: Warburton G. B. , Hutton S. G. 
Published: March 2007

AbstractThe structure is idealized as a uniform slender beam of circular cross‐section which supports a rigid tip mass and which is connected at its base to a rigid foundation mass, the latter being attached to the surface of a visco‐elastic half‐space. An analytical solution for harmonic response of the partially submerged structure is obtained in terms of the normal modes of the corresponding structure in vacuo. This is achieved by introducing fluid‐structure coupling into the model. A similar structural model has been described in a companion paper and used to study soil‐structure interaction. Numerical results show the dependence of response on various parameters and contribute towards a better understanding of the dynamics of off‐shore towers.
Non‐linear analysis of coupled wall systems
Authors: Takayanagi Takehira , Schnobrich William C. 
Published: March 2007

AbstractThe non‐linear response history and failure mechanism of coupled wall systems under dynamic loads and static loads are investigated through an analytical model. The walls and coupling beams are replaced by flexural elements. Axial and shear stiffnesses are included for the wall members. The stiffness characteristics of each member are determined by inelastic properties. The suitable hysteresis loops to each constituent member are established to include the specific characteristics of coupled wall systems. The computed results are compared with results obtained from tests using model structures statically and dynamically tested on the Illinois Earthquake Simulator.
Evaluating the seismic reliability of electrical equipment containing ceramic structural members
Authors: Schiff Anshel J. , Torres‐Cabrejos Rafael E. , Yao James T. P. 
Published: March 2007

AbstractA method for evaluating the reliability of ceramic structural members subjected to earthquake‐induced vibrations is presented. The method uses the Weibull distribution to represent the probability of failure of the brittle ceramic material and includes the effects of stress concentrations introduced by flaws and the volume of material subjected to stress. The stress concentration introduced by the complex form of insulators and at the mounting interfaces is considered. A numerical example is given to illustrate the application of the method.
Seismic response of long curved bridge structures: Experimental model studies
Authors: Williams David , Godden William 
Published: March 2007

AbstractThis paper presents the results of a shaking table study conducted on the seismic behaviour of curved reinforced concrete bridge structures of the type used in highway interchanges. A series of representational 1/30th scale models was constructed in microconcrete to study the effects of both linear and non‐linear dynamic behaviour, the non‐linearity including sliding and impacting at the expansion joints and ductility in the columns. Each model was subjected to a series of increasingly severe simulated earthquakes in the longitudinal and transverse directions, both with and without the vertical component. Response data were recorded in the form of selected displacement time‐histories which were subsequently used as control data in a companion theoretical study. Each model was eventually taken to failure which consisted primarily of extensive damage at the expansion joints. The paper concludes with general observations on the seismic behaviour of long‐span long‐period curved bridges, and emphasizes the sensitivity of this behaviour to the location and design of the joints.
Numerical modelling of the industrial silicon single crystal growth processes
Authors: Nacke Bernard , Muiznieks Andris 
Published: March 2007

AbstractSilicon wafers produced from the silicon single crystals are the basic material for the manufacturing of various kinds of electronic devices determining the everyday life of the modern society. Silicon single crystals industrially are mainly grown by two methods ‐ by the Czochralski and by the floating zone technique. Both of them involve various physical processes with complex interactions which makes the experimental optimization of the growth techniques a rather hard and expensive task. Therefore, mathematical modelling supported by the rapid increase of the computer power has become an effective means in the development of the industrial crystal growth. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transition to Turbulence in the Hartmann Boundary Layer
Authors: Thess André , Krasnov Dmitry , Boeck Thomas , Zienicke Egbert , Zikanov Oleg , Moresco Pablo , Alboussière Thierry 
Published: March 2007

AbstractThe Hartmann boundary layer is a paradigm of magnetohydrodynamic (MHD) flows. Hartmann boundary layers develop when a liquid metal flows under the influence of a steady magnetic field. The present paper is an overview of recent successful attempts to understand the mechanisms by which the Hartmann layer undergoes a transition from laminar to turbulent flow. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of turbulent metal flows
Authors: Baake E. , Umbrashko A. , Nacke B. , Jakovics A. 
Published: March 2007

AbstractComprehensive knowledge of the heat and mass transfer processes in turbulent metal flows is required to realize efficient and reliable melting and casting processes. Experimental and numerical studies of the melt flow in induction furnaces show that the flow pattern, which comprise several vortexes of the mean flow, and the temperature distribution in the melt are significantly influenced by low‐frequency large scale flow oscillations. Two‐ and three‐dimensional hydrodynamic calculations of the melt flow, using two‐equation turbulence models based on Reynolds Averaged Navier‐Stokes approach, do not predict the large scale periodic flow instabilities obtained from the experimental data. That's why the Large Eddy Simulation (LES) numerical technique was approved to be an alternative for the various k ‐ε model modifications. In order to investigate convective scalar transport mechanism in the considered flow the discrete particle tracing approach has been carried out. The studies, presented in this paper, content the numerical simulation of turbulent melt flow of experimental and industrial size induction furnaces and demonstrate the possibility of using the three‐dimensional transient LES approach for successful simulation of heat and mass transfer processes in metallurgical applications. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Control of weakly conductive fluids by near wall Lorentz forces
Authors: Hinze M. 
Published: March 2007

AbstractIn this work optimal and model‐predictive control approaches for control of weakly conductive fluids are developed. The flow around the circular cylinder at low Reynolds numbers serves as prototyping application. Control by near‐wall Lorentz forces gains either to suppress the formation of the von Kármán Vortex Street, or to reduce the drag. Besides a concise mathematical modelling numerical examples are presented which highlight the scope of the presented control approaches. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Forward and inverse problems in MHD: Numerical and experimental results
Authors: Stefani Frank , Gailitis Agris , Gerbeth Gunter , Gundrum Thomas , Xu Mingtian 
Published: March 2007

AbstractWhen a conducting fluid comes under the influence of a magnetic field, electrical currents are induced that give rise to a modification of this magnetic field. The ratio of induced magnetic field to applied magnetic field is characterized by the magnetic Reynolds number Rm of the flow. For large Rm, even self‐excitation of a magnetic field can occur. Thishydromagnetic dynamo effectis responsible for the maintenance of the magnetic fields of planets, stars and galaxies. In the present paper, we delineate some recent developments in the numerical treatment of induction effects in arbitrary geometry, and their application for dynamo experiments as well as for a “Contactless Inductive Flow Tomography (CIFT)”. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Boundary Perturbation Methods for Water Waves
Authors: Nicholls David P. 
Published: March 2007

AbstractThe most successful equations for the modeling of ocean wave phenomena are the free–surface Euler equations. Their solutions accurately approximate a wide range of physical problems from open–ocean transport of pollutants, to the forces exerted upon oil platforms by rogue waves, to shoaling and breaking of waves in nearshore regions. These equations provide numerous challenges for theoreticians and practitioners alike as they couple the difficulties of a free boundary problem with the subtle balancing of nonlinearity and dispersion in the absence of dissipation. In this paper we give an overview of, what we term, “Boundary Perturbation” methods for the analysis and numerical simulation of this “water wave problem”. Due to our own research interests this review is focused upon the numerical simulation of traveling water waves, however, the extensive literature on the initial value problem and additional theoretical developments are also briefly discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mainstreaming rural poor in water resources management: preliminary lessons of a bottom‐up WUA development approach in Central Asia
Authors: Yakubov Murat , Hassan Mehmood Ul 
Published: March 2007

AbstractThis paper draws upon experiences in Central Asia with irrigation management transfer arising from a development project currently underway in the Fergana Valley of Central Asia. One of the main features of the project is that it gives much attention to social mobilization in order to bring required water management change and get those at the grassroots duly organized, educated and empowered to truly self‐own and manage their community‐based organization. The paper, through analysis of users' perception before and after the mobilization, documents the changes in, attitudes and knowledge of, and the performance of water users' associations through, users' perspectives. Though no major breakthroughs have been found so far in the quality of irrigation and drainage services provided, there are clear indications that increased grassroots knowledge and awareness about water and irrigation management through intensive mobilization, regular involvement and exposure of the entire water user community to WUA management, planning and operation matters and decision‐making do have a positive bearing on their attitudes, behaviours, capacities and skills, adding considerably to their overall social capital and thus enhancing their chance for a better livelihood. Copyright © 2007 John Wiley & Sons, Ltd.