bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement of the sign and the magnitude of heteronuclear coupling constants from spin‐state‐edited J‐cross‐polarization NMR experiments
Authors: Parella Teodor , Belloc Jordi , Sánchez‐Ferrando Francesc 
Published: July 2004

AbstractNew spin‐state‐selective (S3) NMR pulse sequences exclusively applying cross‐polarization schemes to achieve optimum homonuclear and heteronuclear 1HX coherence transfer are reported for the simple and accurate measurement of the magnitude and sign of heteronuclear coupling constants for samples at natural abundance. The proposed spin‐edited HCP‐TOCSY experiments are based on clean heteronuclear S3 excitation, generated by simultaneous co‐addition of two independent in‐phase and anti‐phase components created during the mixing heteronuclear J‐cross‐polarization (HCP) step, which is finally transferred to other protons by a conventional homonuclear TOCSY mechanism. Selective 1D and non‐selective 2D approaches for the easy determination of long‐range proton–carbon and proton–nitrogen coupling constants on any protonated and non‐protonated heteronuclei are presented and discussed for several organic molecules. Copyright © 2004 John Wiley & Sons, Ltd.
Restricted structure predictive optimal control
Authors: Grimble M. J. 
Published: July 2004

AbstractThe design of low‐order predictive optimal controllers, that involve a multi‐step cost index and future setpoint knowledge, is considered. The usual predictive controller is of high order and the aim is to develop simpler structures, suitable for applications where PID controllers might be employed. The system is assumed to be represented by a discrete‐time state‐space model, which is very general, and the quadratic cost‐function may include dynamic cost weighting terms. Using this approach, it is straightforward to generate a much lower‐order predictive controller and thereby simplify implementation. Even with a continuing improvement in computational power there are many good reasons why low‐order simple controllers have advantages in real applications. Copyright © 2004 John Wiley & Sons, Ltd.
Optimal investments with convex–concave revenue: a focus‐node distinction
Authors: Hartl Richard F. , Kort Peter M. 
Published: July 2004

AbstractThis paper considers a capital accumulation model in which revenue is a convex–concave function of the capital stock. While for certain capital values increasing returns to scale are reasonable, usually this property does not hold in general. In particular for large capital stock values it becomes increasingly difficult and thus expensive to produce more and more because of limitations of resources or infrastructure, lack of trained personnel in the region, etc. We give a complete classification under which parameter constellations a saddle point equilibrium is optimal, when it is optimal to close down by choosing zero investment and when history dependent equilibria occur. In the last scenario we distinguish between different types of the unstable equilibrium, which can each have their own implication for the firm's investment policy. Copyright © 2004 John Wiley & Sons, Ltd.
Evaluating the best value framework in UK local government services
Authors: McAdam Rodney , Walker Timothy 
Published: July 2004

AbstractThe aim of this article is to conduct an exploratory multiple case analysis of local government delivery of Best Value by focusing on Environmental Waste Management Service (EWMS) delivery. EWMS is chosen as a key area of Best Value development and application. The Best Value framework was developed by the UK Government to introduce performance management to local government as part of the ‘Modernising Government’ agenda. There is a need to critically evaluate Best Value so that local government can determine if this is a suitable and sustainable framework for the management of public services and that it can make a contribution to increased public service effectiveness. The article describes an exploratory multiple case research study and shows that the imposition of Best Value in local government must recognise the complexity and diversity within local government services, rather than adopting an inflexible approach to deployment. There is a need to go beyond generalised performance measures and benchmarks and to attempt to understand the difficulties and complexities of localised conditions. Copyright © 2003 John Wiley & Sons, Ltd.
Taxation and local government accountability in a clientelist context: Colombia
Authors: Merat Jacques 
Published: July 2004

AbstractIncreasing the accountability of local government is an important objective of decentralisation. One way to achieve greater accountability is to enhance the reliance of local governments on locally raised taxes. Property taxes are a prime source of increased revenue for local governments. However, it is difficult to levy them effectively in clientelist political systems, like that of Colombia. Recent reforms there have increased the capacity of municipal governments to raise revenue through property taxation. Giving responsibility for assessments of property values to an independent national agency has been especially useful. Municipal government finances are now to some degree independent and protected from the influence of clientelistic political parties. However continuing problems include: the reluctance of mayors to enforce taxation liabilities; the obstacles to opening local political debates on taxation; and the problems faced by national governments in trying to monitor municipal revenues and expenditures. Copyright © 2003 John Wiley & Sons, Ltd.
Decentralisation of service delivery as adopted by the Central District Council in Botswana
Authors: Meyer‐Emerick Nancy , Mothusi Bashi , Molaodi Daniel K. 
Published: July 2004

AbstractThe Central District Council (CDC) in Botswana expanded service delivery to five sub‐districts in January 2000 using a model adapted from the South Somerset District Council, UK. As little data were available on the effectiveness of decentralised service delivery, officials and councillors throughout CDC were interviewed regarding their perception of the process. They not only provided recommendations for enhanced implementation but also identified some of the tensions resulting from it. Copyright © 2004 John Wiley & Sons, Ltd.
Review of electronic and optical properties of semiconducting π‐conjugated polymers: applications in optoelectronics
Authors: Moliton André , Hiorns Roger C 
Published: July 2004

AbstractA general overview of the optoelectronic properties of π‐conjugated polymers is presented. Two types of polymer are discerned: interchangeable structures of the same energy (degenerate), such as polyacetylene; and non‐degenerate polymers, such as poly(para‐phenylene). The band structures of degenerate and non‐degenerate polymers are related to their conductivities in doped and non‐doped states. In both cases, disorder and impurities play an important role in conductivity. Polarons, bipolarons and excitons are detailed with respect to doping and charge transfers. Given the fibrillic nature of these materials, the variable range hopping (VRH) law for semiconducting polymers is modified to account for metallic behaviours. Optoelectronic properties—electroluminescence and photovoltaic activity—are explained in terms of HOMO and LUMO bands, polaron‐exciton and charge movement over one or more molecules. The properties of H‐ or J‐type aggregates and their effects on transitions are related to target applications. Device structures of polymer light‐emitting diodes are explicitly linked to optimising polaron recombinations and overall quantum efficiencies. The particularly promising use of π‐conjugated polymers in photovoltaic devices is discussed. Copyright © 2004 Society of Chemical Industry
Atom transfer radical polymerization of methyl methacrylate at ambient temperature using soluble Cu(I) complex catalysts formed with mixed ligands of multidentate amines and halide ions
Authors: Chatterjee Dhruba P. , Chatterjee Uma , Mandal Broja M. 
Published: July 2004

AbstractAn Erratum has been published for this article in
J Polym Sci Part A: Polym Chem (2004) 42(19) 5030.The addition of soluble quaternaryammonium halides (QX) in catalytic amounts takes into solution CuX/pentamethyldiethylenetriamine (PMDETA) complex (X = Cl, Br) in methyl methacrylate (MMA). The soluble catalyst complex provided much better control of the polymerization of MMA at ambient temperature than did the insoluble catalyst formed in the absence of QX, with CuCl/PMDETA/Aliquat® 336 (AQCl) proving to be superior to the CuBr/PMDETA/Bu4NBr catalyst system. The effect was independent of the size of the quaternaryammonium ion. Also, the presence of Cl in the catalyst–QX combination either as CuCl or as QCl was enough to give much better control than that provided by a wholly Br‐based system. Among the various initiators used, that is, ethyl 2‐bromoisobutyrate (EBiB), methyl 2‐bromopropionate (MBP), 1‐phenylethyl bromide (PEBr), and p‐toluenesulfonyl chloride (pTsCl), only EBiB gave a satisfactory result. With MBP and PEBr the initiation was slower than the propagation, whereas with pTsCl the initiation was very fast, so that instantaneous termination occurred. The living nature of the polymers was shown by block copolymer preparation. It has been suggested that some of the added halide ions entered into the coordination spheres of Cu(I) and Cu(II), leading to their improved solubility and stronger deactivation by the Cu(II) complex. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4132–4142, 2004
Nitroxide‐mediated free‐radical copolymerization of styrene with butyl acrylate
Authors: Cuervo‐Rodriguez Rocio , Bordegé Vanesa , Fernández‐Monreal Maria Carmen , Fernández‐García Marta , Madruga Enrique L. 
Published: July 2004

AbstractControlled free‐radical copolymerization of styrene (S) and butyl acrylate (BA) was achieved by using a second‐generation nitroxide, N‐tert‐butyl‐N‐[1‐diethylphosphono‐(2,2‐dimethylpropyl)] nitroxide (DEPN), and 2,2‐azobisisobutyronitrile (AIBN) at 120 °C. The time‐conversion first‐order plot was linear, and the number‐average molecular weight increased in direct proportion to the ratio of monomer conversion to the initial concentration, providing copolymers with low polydispersity. The monomer reactivity ratios obtained were rS = 0.74 and rBA = 0.29, respectively. To analyze the convenience of applying the Mayo–Lewis terminal model, the cumulative copolymer composition against conversion and the individual conversion of each monomer as a function of copolymerization time were studied. The theoretical values of the propagating radical concentration ratio were also examined to investigate the copolymerization rate behavior. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4168–4176, 2004
Mixed iridium(III) and ruthenium(II) polypyridyl complexes containing poly(ε‐caprolactone)‐bipyridine macroligands
Authors: Marin Veronica , Holder Elisabeth , Hoogenboom Richard , Schubert Ulrich S. 
Published: July 2004

AbstractA hydroxy‐functionalized bipyridine ligand was polymerized with ε‐caprolactone utilizing the controlled ring‐opening polymerization of ε‐caprolactone in the presence of stannous octoate. The resulting poly(ε‐caprolactone)‐containing bipyridine was characterized by 1H NMR and IR spectroscopy, and gel permeation chromatography, as well as matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry, revealing the successful incorporation of the bipyridine ligand into the polymer chain. Coordination to iridium(III) and ruthenium(II) precursor complexes yielded two macroligand complexes, which were characterized by NMR, gel permeation chromatography, matrix‐assisted laser desorption/ionization time‐of‐flight MS, cyclic voltammetry, and differential scanning calorimetry. In addition, both photophysical and electrochemical properties of the metal‐containing polymers proved the formation of a trisruthenium(II) and a trisiridium(III) polypyridyl species, respectively. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4153–4160, 2004
New polyamidation through the activation of amino groups with phenyl dichlorophosphite in pyridine
Authors: Higashi Fukuji , Yokote Shuhji , Murakawa Tatsuzo 
Published: July 2004

AbstractPolyamidation with phenyl dichlorophosphite (PDCP) as a new condensing agent was studied. A model reaction of benzoic acid and aniline with PDCP through a change in their addition order revealed that PDCP reacted with aniline more favorably than it did with the acid, and it could activate about 2 mol of aniline to produce benzanilide in a nearly quantitative yield. A preferential reaction with aniline occurred even in the presence of the acid. The reaction was applied to the polyamidation of dicarboxylic acids and diamines or of p‐aminobenzoic acid (PABA) with 0.6 equiv of PDCP with respect to the amino groups in pyridine/N‐methyl‐2‐pyrrolidone in the presence of LiCl. Polyterephthalamides and polyisophthalamides with moderate inherent viscosity values were produced. The polycondensation of PABA was significantly promoted by the slow addition of PDCP over a period of 20–40 min and the presence of LiCl, producing poly(p‐benzamide) with inherent viscosity values of about 2.4. Unsubstituted PDCP and PDCPs with an electron‐donating methoxy substituent afforded better results. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4126–4131, 2004
Kinetic analysis of the mechanolysis of polymethylmethacrylate in the course of vibratory ball milling at various mechanical energy
Authors: Kondo Shin‐ichi , Sasai Yasushi , Hosaka Shouichi , Ishikawa Takaaki , Kuzuya Masayuki 
Published: July 2004

AbstractWe carried out the mechanolysis of polymethylmethacrylate (PMMA) at various mechanical energies and analyzed kinetically the mechanoradical concentration and molecular weight at various mechanical energies. The radical concentration gradually increased to a maximum and then gradually decreased after reaching the maximum value. It is suggested that the radical quenching reaction (disproportionation and/or recombination) progressed together with radical formation. Kinetic analysis of the mechanoradical concentration indicated that the actual amounts of mechanoradicals produced were larger than observed. It is also suggested that vast numbers of reactions take place in mechanolysis. The molecular weight decreased exponentially toward the limiting value, and the limiting molecular weight was larger with decreases in mechanical energy. It is also suggested that mechanoradical formation is inversely proportional to the change in molecular weight at any given mechanical energy. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4161–4167, 2004
Synthesis and characterization of novel fluorinated polyimides derived from 4,4′‐[2,2,2‐trifluoro‐1‐(3‐trifluoromethylphenyl)ethylidene]diphthalic anhydride and aromatic diamines
Authors: Yang S. Y. , Ge Z. Y. , Yin D. X. , Liu J. G. , Li Y. F. , Fan L. 
Published: July 2004

AbstractA novel fluorinated aromatic dianhydride, 4,4′‐[2,2,2‐trifluoro‐1‐(3‐trifluoromethyl‐phenyl)ethylidene]diphthalic anhydride (TFDA) was synthesized by coupling of 3′‐trifluoromethyl‐2,2,2‐trifluoroacetophenone with o‐xylene under the catalysis of trifluoromethanesulfonic acid, followed by oxidation of KMnO4 and dehydration. A series of fluorinated aromatic polyimides derived from the novel fluorinated aromatic dianhydride TFDA with various aromatic diamines, such as p‐phenylenediamine (p‐PDA), 4,4′‐oxydianiline (ODA), 1,4‐bis(4‐aminophenoxy)benzene (p‐APB), 1,3‐bis(4‐amino‐phenoxy)benzene (m‐APB), 4‐(4‐aminophenoxy)‐3‐trifluoromethylphenylamine (3FODA) and 1,4‐bis(4‐amino‐2‐trifluoromethylphenoxy)benzene (6FAPB), were prepared by polycondensation procedure. All the fluorinated polyimides were soluble in many polar organic solvents such as NMP, DMAc, DMF, and m‐cresol, as well as some of low boiling point organic solvents such as CHCl3, THF, and acetone. Homogeneous and stable polyimide solutions with solid content as high as 35–40 wt % could be achieved, which were prepared by strong and flexible polyimide films or coatings. The polymer films have good thermal stability with the glass transition temperature of 232–322 °C, the temperature at 5% weight loss of 500–530 °C in nitrogen, and have outstanding mechanical properties with the tensile strengths of 80.5–133.2 MPa as well as elongations at breakage of 7.1–12.6%. It was also found that the polyimide films derived from TFDA and fluorinated aromatic diamines possess low dielectric constants of 2.75–3.02, a low dissipation factor in the range of 1.27–4.50 × 10−3, and low moisture absorptions <1.3%. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4143–4152, 2004
The relative orientation of the Arg and Asp side chains defined by a pseudodihedral angle as a key criterion for evaluating the structure–activity relationship of RGD peptides
Authors: Kostidis Sarantos , Stavrakoudis Athanassios , Biris Nikolaos , Tsoukatos Demokritos , Sakarellos Constantinos , Tsikaris Vassilios 
Published: July 2004

AbstractThe ability of an integrin to distinguish between the RGD‐containing extracellular matrix proteins is thought to be due partially to the variety of RGD conformations. Three criteria have been proposed for the evaluation of the structure–activity relationship of RGD‐containing peptides. These include: (i) the distance between the charged centres, (ii) the distance between the Arg Cβ and Asp Cβ atoms, and (iii) the pseudo‐dihedral angle defining the Arg and Asp side‐chain orientation formed by the Arg Cζ, Arg Cα, Asp Cα and Asp Cγ atoms. A comparative conformation–activity study was performed between linear RGD peptides and strongly constrained cyclic (S,S) ‐CDC‐ bearing compounds, which cover a wide range of inhibition potency of platelet aggregation. It is concluded that the fulfilment of the −45° ≤ pseudo‐dihedral angle ≤ +45° criterion is a prerequisite for an RGD compound to exhibit inhibitory activity. Once this criterion is accomplished, the longer the distance between the charged centres and/or between the Arg and Asp Cβ atoms, the higher is the biological activity. In addition, the stronger the ionic interaction between Arg and Asp charged side chains, the lower the anti‐aggregatory activity. Copyright © 2004 European Peptide Society and John Wiley & Sons, Ltd.
Hybrid α/β3‐peptides with proteinogenic side chains. monosubstituted analogues of the chemotactic tripeptide For‐Met‐Leu‐Phe‐OMe
Authors: Giordano Cesare , Lucente Gino , Mollica Adriano , Nalli Marianna , Zecchini Giampiero Pagani , Paradisi Mario Paglialunga , Gavuzzo Enrico , Mazza Fernando , Spisani Susanna 
Published: July 2004

AbstractThe α/β3‐mixed tripeptides R‐CO‐β3‐HMet‐Leu‐Phe‐OMe (1a,b), R‐CO‐Met‐β3‐HLeu‐Phe‐OMe (2a,b) and R‐CO‐Met‐Leu‐β3‐HPhe‐OMe (3a,b) (a, R = tert‐butyloxy‐; b, R = H−), analogues of the potent chemoattractant For‐Met‐Leu‐Phe‐OMe, have been synthesized by classical solution methods and fully characterized. The activities of the new analogues as chemoattractants, superoxide anion producers and lysozyme releasers have been determined on human neutrophils. Whereas all of the three N‐formyl derivatives are significantly less active than the parent tripeptide as chemoattractants, compound 1b has been found to be highly active as a superoxide anion producer and 3b as a lysozyme releaser. The results show that the replacement of the native Leu residue at the central position is, in each of the examined cases, the least favourable modification. The three N‐Boc derivatives are, as expected, devoid of activity as agonists, but they are all good inhibitors of chemotaxis. Information on the solution conformation has been obtained by examining the involvement of the NH groups in intramolecular H‐bonds using 1H NMR. The conformation of the N‐Boc analogue 1a has also been determined in the crystal state by x‐ray diffraction analysis. The molecule is extended at the β3‐HMet residue (φ1 = −87°;θ1 = 172°;ψ1 = 126° ) and no intramolecular H‐bond is present. Copyright © 2004 European Peptide Society and John Wiley & Sons, Ltd.
Electron‐impact single ionization cross sections of helium isoelectronic systems
Authors: Uddin M. Alfaz , Basak A. K. , Saha B. C. 
Published: July 2004

AbstractThe cross sections for electron‐impact single ionization of helium‐like targets,—Li+, B3+, C4+, N5+, O6+, Ne8+, Na9+, Fe24+, Ag45+, and U90+—are calculated using a recently propounded parameter‐free relativistic binary encounter (RBEA) model, which remains valid up to the relativistic energy domain. Our RBEA results are compared with those of the Coulomb–Born (CB) approximation, distorted wave Born approximation (DWBA), relativistic two‐potential DWBA (RTPD), the simple empirical model of Brenshtam et al. (BRY), and the model of Deutsch and Märk (DM) along with the available experimental data. The RBEA model, while keeping the comparable predictive power of cross sections, is found to overcome the limitations of the empirical BRY and DM models with their fitting parameters, and the quantum mechanical CB, DWBA, and RTPD theories with arduous and lengthy calculations. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Spatial partitioning of the molecular wave function: Reexamination of the bond‐charge model of covalent binding
Authors: Camparo James 
Published: July 2004

AbstractOwing to the complexity of many‐body quantum interactions, theoretical problems in chemistry almost always necessitate numerical methods of solution. In turn, and somewhat paradoxically, this reliance on computation often precipitates a need for approximate models that can provide a conceptual framework for the interpretation of the accurate numerical solutions. In this report, we reexamine and improve upon the simple bond‐charge (SBC) model of Parr and Borkman with the express purpose of examining its role as a suitable intuitive model for bonding energetics. We first discuss the role of spatial partitioning in the SBC model and the molecular‐structure approximations that are implicit within the model. We then develop an improved version of the model by including electrostatic repulsion between shared electron pairs; we refer to this enhanced version as a semiempirical charge‐cloud (SCC) model. Applying the SCC model to a broad range of diatomics, we find that it is able to predict dissociation energies on a par with simple variational calculations. As an illustrative application of the SCC model, we use it to estimate unknown dissociation energies and rotational constants for a number of alkali dimers. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Highly accurate numerical results for three‐center nuclear attraction and two‐electron Coulomb and exchange integrals over Slater‐type functions
Authors: Safouhi Hassan 
Published: July 2004

AbstractThe present work focuses on the recent progress in nonlinear transformation methods for improving the convergence of highly oscillatory integrals and in their applications for an efficient and rapid numerical evaluation of molecular electronic integrals over Slater‐type functions (STFs). The nonlinear D transformation, which is probably the most effective general approach for increasing the rate of convergence of semi‐infinite oscillatory integrals, is presented. Molecular integrals over STFs are expressed as finite linear combinations of integrals over B functions. The basis set of B functions is suitable to apply the Fourier transform method, which led to analytic expressions, involving highly oscillatory functions, for molecular integrals. Efficient algorithms based on the D transformation are now developed for a numerical evaluation of molecular integrals over STFs. Numerical results that we obtained with linear and nonlinear molecules, and which are in agreement with those obtained using existing codes (Alchemy, STOP, and ADGGSTNGINT), show that the algorithms described in this work are relevant. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004