bluuebunny/crossref_metadata_2025_split huggingface dataset:
Functionalized Nanodiamonds Part I. An Experimental Assessment of Diamantane and Computational Predictions for Higher Diamondoids
Authors: Fokin Andrey A. , Tkachenko Boryslav A. , Gunchenko Pavel A. , Gusev Dmitriy V. , Schreiner Peter R. 
Published: September 2005

AbstractThe structures, strain energies, and enthalpies of formation of diamantane 1, triamantane 2, isomeric tetramantanes 3–5, Td‐pentamantane 6, and D3d‐hexamantane 7, and the structures of their respective radicals, cations, as well as radical cations, were computed at the B3LYP/6‐31G* level of theory. For the most symmetrical hydrocarbons, the relative strain (per carbon atom) decreases from the lower to the higher diamondoids. The relative stabilities of isomeric diamondoidyl radicals vary only within small limits, while the stabilities of the diamondoidyl cations increase with cage size and depend strongly on the geometric position of the charge. Positive charge located close to the geometrical center of the molecule is stabilized by 2–5 kcal mol−1. In contrast, diamondoid radical cations preferentially form highly delocalized structures with elongated peripheral CH bonds. The effective spin/charge delocalization lowers the ionization potentials of diamondoids significantly (down to 176.9 kcal mol−1 for 7). The reactivity of 1 was extensively studied experimentally. Whereas reactions with carbon‐centered radicals (Hal)3C. (Hal=halogen) lead to mixtures of all possible tertiary and secondary halodiamantanes, uncharged electrophiles (dimethyldioxirane, m‐chloroperbenzoic acid, and CrO2Cl2) give much higher tertiary versus secondary selectivities. Medial bridgehead substitution dominates in the reactions with strong electrophiles (Br2, 100 % HNO3), whereas with strong single‐electron transfer (SET) acceptors (photoexcited 1,2,4,5‐tetracyanobenzene) apical C4H bridgehead substitution is preferred. For diamondoids that form well‐defined radical cations (such as 1 and 4–7), exceptionally high selectivities are expected upon oxidation with outer‐sphere SET reagents.
Simulation of 59Co NMR Chemical Shifts in Aqueous Solution
Authors: Bühl Michael , Grigoleit Sonja , Kabrede Hendrik , Mauschick Frank T. 
Published: September 2005

Abstract59Co chemical shifts were computed at the GIAO‐B3LYP level for [Co(CN)6]3−, [Co(H2O)6]3+, [Co(NH3)6]3+, and [Co(CO)4]− in water. The aqueous solutions were modeled by Car–Parrinello molecular dynamics (CPMD) simulations, or by propagation on a hybrid quantum‐mechanical/molecular‐mechanical Born–Oppenheimer surface (QM/MM‐BOMD). Mean absolute deviations from experiment obtained with these methods are on the order of 400 and 600 ppm, respectively, over a total δ(59Co) range of about 18 000 ppm. The effect of the solvent on δ(59Co) is mostly indirect, resulting primarily from substantial metal–ligand bond contractions on going from the gas phase to the bulk. The simulated solvent effects on geometries and δ(59Co) values are well reproduced by using a polarizable continuum model (PCM), based on optimization and perturbational evaluation of quantum‐mechanical zero‐point corrections.
“Heavy Fluorous” Cyclopentadienes and Cyclopentadienyl Complexes with Three to Five Ponytails: Facile Syntheses from Polybromocyclopentadienyl Complexes, Phase Properties, and Electronic Effects
Authors: Dinh Long V. , Gladysz John A. 
Published: September 2005

AbstractThe reactions between [(η5‐C5H5−xBrx)M(CO)3] (M=Re, Mn; x=1, 3, 4, 5) and [IZn{(CH2)nRf8}] (n=2, 3; Rf8=(CF2)7CF3) in the presence of [Cl2PdL2] catalysts give the title complexes [{η5‐C5H5−x[(CH2)nRf8]x}M(CO)3]. In the case of x=5, the major product is actually [{η5‐C5H[(CH2)nRf8]4}M(CO)3], in which one of the bromides has been substituted by hydride. Minor amounts of multiple hydride substitution products are formed, all of them readily separable on fluorous silica gel. Irradiation of the manganese complexes in CF3C6H5/MeOH/ether gives uncoordinated cyclopentadienes, which can be deprotonated and reattached to other metals. Partition coefficients have been measured (CF3C6F11/toluene): complexes with three or more ponytails are highly fluorophilic, with values of >99.8:<0.2. The IR $\tilde \nu $CO bands have been used to probe the inductive effects of the ponytails at the metal centers.
Micelles for the Self‐Assembly of “Off–On–Off” Fluorescent Sensors for pH Windows
Authors: Diaz‐Fernandez Yuri , Foti Francesco , Mangano Carlo , Pallavicini Piersandro , Patroni Stefano , Perez‐Gramatges Aurora , Rodriguez‐Calvo Simon 
Published: September 2005

AbstractA micellar approach is proposed to build a series of systems featuring an “off–on–off” fluorescent window response with changes in pH. The solubilizing properties of micelles are used to self‐assemble, in water, plain pyrene with lipophilized pyridine and tertiary amine moieties. Since these components are contained in the small volume of the same micelle, pyrene fluorescence is influenced by the basic moieties: protonated pyridines and free tertiary amines behave as quenchers. Accordingly, fluorescence transitions from the “off” to the “on” state, and viceversa, take place when the pH crosses the pKa values of the amine and pyridine fragments. To obtain an “off–on–off” fluorescent response in this investigation we use either a set of dibasic lipophilic molecules (containing covalently linked pyridine and tertiary amine groups) or combinations of separate, lipophilic pyridines and tertiary amines. The use of combinations of dibasic and monobasic lipophilic molecules also gives a window‐shaped fluorescence response with changes in pH: it is the highest pyridine pKa and the lowest tertiary amine pKa that determine the window limits. The pKa values of all the examined lipophilic molecules were determined in micelles, and compared with the values found for the same molecules in solvent mixtures in which they are molecularly dispersed. The effect of micellization is to significantly lower the observed protonation constants of the lipophilized species. Moreover, the more lipophilic a molecule is, the lower the observed logK value is. Accordingly, changing the substituents on the basic moieties or modifying their structure, tuning the lipophilicity of the mono‐ or dibases, and choosing among a large set of possible combination of lipophilized mono‐ and dibases have allowed us to tune, almost at will, both the width and the position along the pH axis of the obtained fluorescent window.
Silver Nanocluster Redox‐Couple‐Promoted Nonclassical Electron Transfer: An Efficient Electrochemical Wolff Rearrangement of α‐Diazoketones
Authors: Sudrik Surendra G. , Chaki Nirmalya K. , Chavan Vilas B. , Chavan Sambhaji P. , Chavan Subhash P. , Sonawane Harikisan R. , Vijayamohanan K. 
Published: September 2005

AbstractIn this work we report the unique electrocatalytic role of benzoic acid protected silver nanoclusters (Agn, mean core diameter 2.5 nm) in the Wolff rearrangement (Scheme 1) of α‐diazoketones. More specifically, the presence of a Agn0/Agn+ redox couple facilitates a nonclassical electron‐transfer process, involving chemical reaction(s) interposed between two electron‐transfer steps occurring in opposite directions. Consequently, the net electron transfer between the electron mediator (Agn) and α‐diazoketone is zero. In‐situ UV‐visible studies using pyridine as a nucleophilic probe indicate the participation of α‐ketocarbene/ketene as important reaction intermediates. Controlled potential coulometry of α‐diazoketones using Agn as the anode results in the formation of Wolff rearranged carboxylic acids in excellent yield, without sacrificing the electrocatalyst.
A Promising MgII‐Ion‐Selective Luminescent Probe: Structures and Properties of Dy–Mn Polymers with High Symmetry
Authors: Zhao Bin , Gao Hong‐Ling , Chen Xiao‐Yan , Cheng Peng , Shi Wei , Liao Dai‐Zheng , Yan Shi‐Ping , Jiang Zong‐Hui 
Published: September 2005

AbstractTwo Dy–Mn polymers, {[Dy(L1)3Mn1.5(H2O)3]⋅3.125 H2O}n (1, L1=pyridine‐2,6‐dicarboxylic acid) and {[Dy(L2)3Mn1.5(H2O)6]⋅8.25 H2O}n (2, L2=4‐hydroxylpyridine‐2,6‐dicarboxylic acid), with high symmetry (S6) have been prepared. Polymer 1 has a nanoporous 3D framework with channel of about 17.6 Å diameter, while 2 has a honeycomb‐type 2D structure with the cavity of approximately 14.4 Å diameter. In the construction of multidimensional porous polymers with 3d–4f mixed metals, it is the first observation that a ligand substituent effect leads to dramatic differences in the structures formed. Luminescent studies reveal that the emission intensities of 1 and 2 increase significantly upon the addition of Mg2+, whereas the introduction of other metal ions leaves the intensity unchanged or even weakens it; hence, both of them may serve as good candidates of Mg2+ luminescent probes. To our knowledge, complex 1 is also the first example of a 3d–4f metal‐based nanoporous polymer to exhibit luminescent selectivity for Mg2+. Magnetic susceptibility measurements reveal a rather rare ferromagnetic interaction in 2. Thermal gravimetric analyses and powder X‐ray diffraction investigations have also been performed, suggestive of high thermal stability of 1.
Anhydrous Phosphazenium Fluorides as Sources for Extremely Reactive Fluoride Ions in Solution
Authors: Schwesinger Reinhard , Link Reinhard , Wenzl Peter , Kossek Sebastian 
Published: September 2005

AbstractSeveral peralkylated polyaminophosphazenium cations were evaluated for the generation of novel anhydrous F−salts. Two of them have been characterized by X‐ray analysis and are particularly soluble, even in apolar aprotic solvents like benzene or THF, one of them even at −30 °C. Such solutions probably represent the most basic metal‐free and stable media known to date. Comparison of these fluorides with known F−sources demonstrates that they are of unprecedented reactivity and selectivity in E2 elimination reactions.
DNA transitions induced by binding of PARP‐1 to cruciform structures in supercoiled plasmids
Authors: Chasovskikh Sergey , Dimtchev Alexandre , Smulson Mark , Dritschilo Anatoly 
Published: September 2005

AbstractBackgroundPoly(ADP‐ribose)polymerase‐1 (PARP‐1) binds to single and double‐stranded breaks in DNA, but less well known is its affinity for undamaged DNA. Previously, we have shown that PARP‐1 also binds to the hairpin structures in DNA models. The mechanism underlying these interactions remains to be defined.MethodsWe analyzed atomic force microscopy (AFM) images of complex of PARP‐1 proteins with supercoiled plasmids containing cruciform structures. Using volume measurement analysis of molecules of PARP‐1, we determined the numbers of PARP‐1 molecules interacting with supercoiled DNA plasmids containing one cruciform structure. We also determined the extent of supercoiling of plasmids.ResultsOur observations show that PARP‐1 binds to sequences that transition from B‐DNA to cruciform structures. PARP‐1 is present at the ends of hairpin arms, sites containing a 4‐base single‐stranded DNA. Furthermore, interaction of PARP‐1 with supercoiled plasmids leads to a more relaxed plasmid‐DNA conformation.ConclusionsBinding of PARP‐1 to cruciform DNA offers insight into possible mechanisms underlying with changes in DNA conformation. These observations may offer insight into mechanisms involving DNA conformation related to process such as DNA repair and transcription. © 2005 Wiley‐Liss, Inc.
X‐ray phase identification of chocolate is possible without the removal of sugar
Authors: Guthrie Sarah E. , Mazzanti Gianfranco , Idziak Stefan H. J. 
Published: September 2005

AbstractWhen examining chocolate samples by means of X‐ray diffraction, it has become common practice for any sugar to be removed through repeated rinsing in cold water. While necessary in some cases, we show that it is possible to determine the phase of certain dark chocolate samples without sugar removal, through examination of distinctive X‐ray diffraction peaks corresponding to lattice spacings of 3.98 and 3.70 Å.
Optimal design of supplemental viscous dampers for linear framed structures
Authors: Lavan Oren , Levy Robert 
Published: September 2005

AbstractA methodology for the optimal design of supplemental viscous dampers for framed structures is presented. It addresses the problem of minimizing the added damping subject to a constraint on the maximal interstorey angular drift for an ensemble of realistic ground motion records while assuming linear behaviour of the damped structure. The solution is achieved by actually solving an equivalent optimization problem of minimizing the added damping subject to a constraint on a maximal weighted integral on the squared angular drift. The computational effort is appreciably reduced by first using one ‘active’ ground motion record. If the resulting optimal design fails to satisfy the constraints for other ground motions from the original ensemble, additional ground motions (loading conditions) are added one by one to the ‘active’ set until the optimum is reached. An efficient selecting process which is presented herein will usually require one or two records to attain an optimum design.Examples of optimal designs of supplemental dampers are presented for a 2‐storey shear frame and a 10‐storey industrial frame. The 2‐storey shear frame is required to withstand one given ground motion whereas the 10‐storey frame is required to withstand an ensemble of twenty ground motions. The resulting viscously damped structures have envelope values of interstorey drifts equal or less than the target drifts. Copyright © 2005 John Wiley & Sons, Ltd.
Time‐harmonic response of non‐homogeneous elastic unbounded domains using the scaled boundary finite‐element method
Authors: Bazyar Mohammad Hossein , Song Chongmin 
Published: September 2005

AbstractThe scaled boundary finite‐element method is extended to simulate time‐harmonic responses of non‐homogeneous unbounded domains with the elasticity modulus and mass density varying as power functions of spatial coordinates. The unbounded domains and the elasticity matrices are transformed to the scaled boundary coordinates. The scaled boundary finite‐element equation in displacement amplitudes are derived directly from the governing equations of elastodynamics. To enforce the radiation condition at infinity, an asymptotic expansion of the dynamic‐stiffness matrix for high frequency is developed. The dynamic‐stiffness matrix at lower frequency is obtained by numerical integration of ordinary differential equations. Only the boundary is discretized yielding a reduction of the spatial dimension by one. No fundamental solution is required. Material anisotropy is modelled without additional efforts. Examples of two‐ and three‐dimensional non‐homogeneous isotropic and transversely isotropic unbounded domains are presented. The results demonstrate the accuracy and simplicity of the scaled boundary finite‐element method. Copyright © 2005 John Wiley & Sons, Ltd.
Macro–micro analysis method for wave propagation in stochastic media
Authors: Ichimura T. , Hori M. 
Published: September 2005

AbstractThis paper presents a new analysis method, called macro–micro analysis method (MMAM) for numerical simulation of wave propagation in stochastic media, which could be used to predict distribution of earthquake strong motion with high accuracy and spatial resolution. This MMAM takes advantage of the bounding medium theory (BMT) and the singular perturbation expansion (SPE). BMT can resolve uncertainty of soil and crust structures by obtaining optimistic and pessimistic estimates of expected strong motion distribution. SPE leads to efficient multi‐scale analysis for reducing a huge amount of computation. The MMAM solution is given as the sum of waves of low resolution covering a whole city and waves of high resolution for each city portion. This paper presents BMT and SPE along with the formulation of MMAM for wave propagation in three‐dimensional elastic media. Application examples are presented to verify the validity of the MMAM and demonstrate potential usefulness of this approach. In a companion paper (Earthquake Engng. Struct. Dyn., this issue) application examples of earthquake strong motion prediction are also presented. Copyright © 2005 John Wiley & Sons, Ltd.
Analytical expression between the impact damping ratio and the coefficient of restitution in the non‐linear viscoelastic model of structural pounding
Authors: Jankowski Robert 
Published: September 2005

AbstractEarthquake‐induced structural pounding has been recently intensively studied with the help of different models of impact force. It has been verified through comparisons, that the non‐linear viscoelastic model may be considered somewhat the most accurate one among them. The aim of this short paper is to derive an approximating formula relating the impact damping ratio, as a parameter of the model mentioned, with a more widely used coefficient of restitution. The accuracy of the derived analytical formulation has been confirmed through the comparison with the results of numerical simulations. Copyright © 2005 John Wiley & Sons, Ltd.
Pressure boundary condition for the time‐dependent incompressible Navier–Stokes equations
Authors: Sani R. L. , Shen J. , Pironneau O. , Gresho P. M. 
Published: September 2005

AbstractIn Gresho and Sani (Int. J. Numer. Methods Fluids 1987; 7:1111–1145; Incompressible Flow and the Finite Element Method, vol. 2. Wiley: New York, 2000) was proposed an important hypothesis regarding the pressure Poisson equation (PPE) for incompressible flow: Stated there but not proven was a so‐called equivalence theorem (assertion) that stated/asserted that if the Navier–Stokes momentum equation is solved simultaneously with the PPE whose boundary condition (BC) is the Neumann condition obtained by applying the normal component of the momentum equation on the boundary on which the normal component of velocity is specified as a Dirichlet BC, the solution (u, p) would be exactly the same as if the ‘primitive’ equations, in which the PPE plus Neumann BC is replaced by the usual divergence‐free constraint (∇ · u = 0), were solved instead.This issue is explored in sufficient detail in this paper so as to actually prove the theorem for at least some situations. Additionally, like the original/primitive equations that require no BC for the pressure, the new results establish the same thing when the PPE approach is employed. Copyright © 2005 John Wiley & Sons, Ltd.
The relationship of MPDATA to other high‐resolution methods
Authors: Rider W. J. 
Published: September 2005

AbstractHigh‐resolution methods have produced the ability to conduct large eddy simulations without the benefit of an explicit subgrid model. This capability is known as implicit large eddy simulation (ILES). A number of high‐resolution methods have been shown to have this property. There are notable exceptions where high‐resolution method do not work as ILES, particularly methods that have a leading 𝒪(h2) dissipative term. On the other hand, MPDATA is an effective ILES method with a leading 𝒪(h2) dissipative term. This dichotomy has played a key role in the discovery of the key role of conservation or control volume form in producing ILES results. In the process of this analysis, I describe a variant of the method leading to a useful alternative form of sign‐preserving limiters. This form is proposed as an extension of the basic MPDATA methodology allowing some flexibility in the choice of effective high‐order methods. This multistage version of the algorithm removes the leading order nonlinear dissipative error. I rediscover the recursive form of the MPDATA iteration through modified equation analysis (MEA). Finally, returning to the original purpose of the analysis, I describe how the different principles used in MPDATA have been an important contributor to the recent theoretical understanding of ILES.MPDATA is compared with monotone high‐resolution methods both analytically and computationally. The numerical comparison focuses on the validation of ILES methods for high Reynolds number decaying isotropic turbulence. Copyright © 2005 John Wiley & Sons, Ltd.
It's not justwhatyou do, it's thewaythat you do it: the effect of different payment card formats and survey administration on willingness to pay for health gain
Authors: Smith Richard D. 
Published: September 2005

AbstractA general population sample of 314 Australian respondents were randomly allocated to complete a contingent valuation survey administered by face‐to‐face or telephone (‘phone‐mail‐phone’) interview. Although the telephone interview was quicker to complete, no significant difference was found in values obtained through either method. Within each sub‐sample, respondents were also randomly allocated to the three different versions of the payment card (PC) questionnaire format: values listed from high‐to‐low, values listed from low‐to‐high and values randomly shuffled. The high‐to‐low version resulted in significantly higher values than the other versions. Further analyses indicate that the randomly shuffled PC version may produce the most ‘valid’ values. Copyright © 2005 John Wiley & Sons, Ltd.
Changes in the expression of plasma membrane calcium extrusion systems during the maturation of hippocampal neurons
Authors: Kip Sertac N. , Gray Noah W. , Burette Alain , Canbay Ali , Weinberg Richard J. , Strehler Emanuel E. 
Published: September 2005

AbstractSpatial and temporal control of intracellular calcium signaling is essential for neuronal development and function. The termination of local Ca2+ signaling and the maintenance of basal Ca2+ levels require specific extrusion systems in the plasma membrane. In rat hippocampal neurons (HNs) developing in vitro, transcripts for all isoforms of the plasma membrane Ca2+ pump and the Na/Ca2+ exchanger, and the major nonphotoreceptor Na+/Ca2+,K+ exchangers (NCKX) were strongly upregulated during the second week in culture. Upregulation of plasma membrane calcium ATPases (PMCAs)1, 3, and 4 mRNA coincided with a splice shift from the ubiquitous b‐type to the neuron‐specific a‐type with altered calmodulin regulation. Expression of all PMCA isoforms increased over 5‐fold during the first 2 weeks. PMCA immunoreactivity was initially concentrated in the soma and growth cones of developing HNs. As the cells matured, PMCAs concentrated in the dendritic membrane and often colocalized with actin‐rich dendritic spines in mature neurons. In the developing rat hippocampal CA1 region, immunohistochemistry confirmed the upregulation of all PMCAs and showed that by the end of the second postnatal week, PMCAs1, 2, and 3 were concentrated in the neuropil, with less intense staining of cell bodies in the pyramidal layer. PMCA4 staining was restricted to a few cells showing intense labeling of the cell periphery and neurites. These results establish that all major Ca2+ extrusion systems are strongly upregulated in HNs during the first 2 weeks of postnatal development. The overall increase in Ca2+ extrusion systems is accompanied by changes in the expression and cellular localization of different isoforms of the Ca2+ pumps and exchangers. The accumulation of PMCAs in dendrites and dendritic spines coincides with the functional maturation in these neurons, suggesting the importance of the proper spatial organization of Ca2+ extrusion systems for synaptic function and development. © 2005 Wiley‐Liss, Inc.