Dynamic scattering in binary compensate cholesteric mixture with pleochroic dye added

The paper reports measurements of optical transmittance and of I–V characteristic performed simultaneously on the same host mixture ChCl + LCh 74:26% molar in which was introduced another azocumilphenol derivative from paraphenetidine (Dpf). The optical and electrical measurements were interpreted by correlating them with the microstructural aspects recorded by a polarizing microscope in the same conditions of field and temperature.     

Preserving mapping consistency under schema changes

In dynamic environments like the Web, data sources may change not only their data but also their schemas, their semantics, and their query capabilities. When a mapping is left inconsistent by a schema change, it has to be detected and updated. We present a novel framework and a tool (ToMAS) for automatically adapting (rewriting) mappings as schemas evolve. Our approach considers not only local changes to a schema but also changes that may affect and transform many components of a schema. Our algorithm detects mappings affected by structural or constraint changes and generates all the rewritings that are consistent with the semantics of the changed schemas. Our approach explicitly models mapping choices made by a user and maintains these choices, whenever possible, as the schemas and mappings evolve. When there is more than one candidate rewriting, the algorithm may rank them based on how close they are to the semantics of the existing mappings.Received: 13 January 2004, Accepted: 26 March 2004, Published online: 12 August 2004Edited by: M. Carey     

On heat transfer in external natural convection flows using two nanofluids

In the present work, a theoretical model based on the integral formalism approach for both laminar and turbulent external natural convection is extended to nanofluids. By using empirical models based on experimental data for computing viscosity and thermal conductivity of water–alumina and water–CuO suspensions, a close attention is first focused on the influence due to increasing the volume fraction of nanoparticles on the heat transfer and then to the transition threshold between laminar and turbulent regimes. The heat transfer is shown to strongly depend on the flow regime and on particle volume fraction. A clear degradation of heat transfer is observed using nanofluids while compared to that of the base-fluid. Moreover, the fact of increasing the particle volume fraction tends to delay the occurrence of the flow transition to turbulence.     

Polymeric Materials with Magnetic Properties

The paper deals with the study of the magnetic properties of some mechanochemically synthesized polychelates. Some spectral analysis methods such as ESR spectroscopy, atomic absorption spectroscopy, and especially Mössbauer spectroscopy are used for this purpose. The presence of metallic atoms (especially Fe) is responsible for the magnetic properties of these mechanochemically synthesized macromolecular compounds.     

Polymerization of Styrene Initiated with Cumyl 4-t-Butylazo-4-Cyanoperoxypentanoate

The paper reports on the synthesis of a new bifunctional radicalic initiator and its behavior in the polymerization process. The synthesis of cumyl 4-t-butylazo-4-cyanoperoxypentanoate has been achieved by condensation of the corresponding acid chloride with cumen hydroperoxide. The structure of the azo perester is confirmed by IR, UV, and NMR spectra. The initiator has been used in styrene polymerization and the conversion of the polymer studied in connection to monomer and initiator concentration, time of reaction, and temperature. In compliance with multiple regression method, an equation correlating the PS conversion with the previously mentioned variables has been established.     

Impact of Some Properties of Quaternized Polysulfone/Poly(Vinylidene Fluoride) Blend on the Potential Biomedical Applications

Blends of quaternized polysulfones with triphenylphosphonium pendant groups/poly(vinylidene fluoride) were analyzed to establish their impact on the rheological, morphological and surface properties, as well as their interactions with some blood compounds. The rheological functions reflect the influence of both polymers’ chemical structures. Blend compositions of the corresponding films influence the surface tension parameters, increase blend hydrophobicity and, implicitly, decrease the polar surface tension parameters. The specific surface characteristics of polymer blends are related to their interactions with some blood constituents and plasma proteins. Also, the specific microarchitecture of the blend represents an excellent scaffold for medical applications.     

Network model for the viscoelastic behavior of polymer nanocomposites

A theoretical network model reproducing some significant features of the viscoelastic behavior of unentangled polymer melts reinforced with well dispersed non-agglomerated nanoparticles is presented. Nanocomposites with low filler volume fraction (∼10%) and strong polymer-filler interactions are considered. The model is calibrated based on results obtained from discrete simulations of the equilibrium molecular structure of the material. This analysis provides the statistics of the network of chains connecting fillers, of dangling strands having one end adsorbed onto fillers, and that of the population of loops surrounding each nanoparticle. The network kinetics depends on the attachment-detachment dynamics of grafted chains of various types and is modeled by using a set of convection equations for the probability distribution functions. The overall viscoelastic response depends strongly on the lifetime of the polymer-filler junctions. The largest reinforcement is observed at low strain rates and low frequency oscillations. A solid like behavior is predicted for systems in which the polymer molecules interact strongly with the nanoparticles, effect which is associated with the behavior of the network of bridging segments.     

Adsorption studies of Cr(III) ions from aqueous solutions by DEHPA impregnated onto Amberlite XAD7 – Factorial design analysis

The present paper investigates the adsorption of Cr(III) ions using the SIR, prepared by impregnation of Amberlite XAD7 with di-(2-ethylhexyl)-phosphoric acid (DEHPA), which has been chosen as an extractant for the purpose of this study. The Amberlite XAD7–DEHPA resin was impregnated with DEHPA and ethylic alcohol as solvent trough dynamic column impregnation method. The influence of different physicochemical parameters (pH, resin dosage, initial concentration of Cr(III) ions, contact time and temperature) upon the adsorption capacity of XAD7–DEHPA, in the Cr(III) ions removal process from aqueous solution, has been investigated. The pH for Cr(III) ions adsorption was found as 3.0 for this material. The results showed that the adsorption equilibrium was reached after 45 min. The adsorption process is best described by the pseudo-second order kinetic model. Langmuir adsorption isotherm gave a satisfactory fit of the equilibrium data. The maximum adsorption capacity is ∼3 mg Cr(III) ions/g SIR. The thermodynamic studies allowed us to determine the thermodynamic parameters ΔG°, ΔH° and ΔS°. In this paper the factorial design of experiments was used to study the performance of the adsorption process.     

Inter-organizational innovation and cloud computing

Firms are increasingly shifting from the ‘closed’ innovation paradigm, in which their innovation design and implementation activities were based on their own internal knowledge resources, skills and production facilities, towards the inter-organizational ‘open’ innovation paradigm, which is based to a significant degree on collaboration with other organizations, aiming at the exploitation of external knowledge resources, skills and production facilities as well. This paper investigates empirically the effects of firm’s inter-organizational collaboration for the design and implementation of innovations, and also use of ICT for supporting this collaboration, on firm’s propensity to adopt cloud computing (CC), and in this way it examines in an ‘objective’ manner to what extent firms regard CC as a cost-effective means of supporting inter-organizational collaboration for the design and implementation of innovation. Our study is based on a dataset collected in the e-Business Survey of the European Commission from 676 European firms from the glass, ceramics and cement manufacturing sectors. It has been concluded that firms of these sectors regard CC as a cost-effective means of supporting collaboration with other firms for the design of innovations in their products, services and processes, and also of reducing the costs and increasing the capabilities and flexibility of already existing electronic support of inter-organizational innovation design collaboration. Furthermore, our results indicate that firms find CC useful for the reduction of the costs and the increase of the capabilities and flexibility of their existing electronic support of the complex operations required for the inter-organizational implementation of innovations.