bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydroquinone and Resorcinol‐Containing Copolyesters
Authors: Andrade Genara S. , Schiraldi David A. , Collard David M. 
Published: July 2005

AbstractSummary: The successful incorporation of hydroquinone in thermal polyesterifications to prepare rigid linear copolyesters is hindered by the leaving group ability of phenols in nucleophilic acyl substitution reactions, the low nucleophilicity of phenols relative to aliphatic alcohols, and its volatility. To overcome these obstacles, with particular regard to improving the properties of poly(ethylene terephthalate), PET, we chose an approach whereby dyad‐based AB‐type mono(acetoxyphenyl) terephthalate monomers are transesterified into PET. In contrast to attempts to copolymerize terephthalic acid, ethylene glycol (EG) and hydroquinone, the transterification of small amounts (<10 mol‐%) of the preformed dyad in the absence of aliphatic diol, provides homogeneous random copolymers. Incorporation of larger amounts of aromatic diol gave only partly soluble materials. NMR analysis of the soluble fraction (in 20 vol.‐% TFA:CHCl3) indicated that the copolymers are substantially random. Transesterification of mono(4‐acetoxyphenyl) terephthalate (hydroquinone‐terephthalic acid, 1) and mono(3‐acetoxyphenyl) terephthalate (resorcinol‐terephthalic acid, 2) into PET allows us to further explore the effect of mesogen structure on the development of liquid crystalline copolyesters.
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Morphology and Dielectric Property of Homogenous BaTiO3/PVDF Nanocomposites Prepared via the Natural Adsorption Action of Nanosized BaTiO3
Authors: Dang Zhi‐Min , Wang Hai‐Yan , Zhang Yi‐He , Qi Jian‐Quan 
Published: July 2005

AbstractSummary: The development of a novel technique for the preparation of homogeneous BaTiO3/polyvinylidene fluoride (BT/PVDF) nanocomposites without obvious agglomeration of BaTiO3 particles was reported in this communication. The morphology, structure, and frequency dependence of the dielectric properties of the nanocomposites were characterized. All results show that the dielectric properties of the nanocomposites in this study are desirable, and the process for preparing the nanocomposites has potential applications in the electronic industry.TEM micrograph of dry BT/PVDF mixtures with nanosized BT particles.magnified imageTEM micrograph of dry BT/PVDF mixtures with nanosized BT particles.
Fabrication of Au/Titania Composite Nanodot Arrays from Au‐Loaded Block Copolymer Micellar Films
Authors: Li Xue , Göring Petra , Pippel Eckhard , Steinhart Martin , Kim Dong Ha , Knoll Wolfgang 
Published: July 2005

AbstractSummary: A simple route to an ordered array of metal/semiconductor oxide composite nanodots is presented. Micellar monolayer films of polystyrene‐block‐poly(2‐vinyl pyridine) (PS‐b‐P2VP) loaded with HAuCl4 in the P2VP nanodomains are used as templates. TiO2 is generated selectively within the polar P2VP domains of PS‐b‐P2VP/HAuCl4 films by chemical vapor deposition of TiCl4. Subsequent removal of the organic matrix by oxygen plasma or UV light leads to an array of Au/TiO2 composite nanoparticles on the substrate surface.Schematic illustration of the process to fabricate an array of Au/titania composite nanodots.magnified imageSchematic illustration of the process to fabricate an array of Au/titania composite nanodots.
Multi‐Objective Optimization of a Batch Copoly(ethylene‐polyoxyethylene terephthalate) Reactor Using Different Adaptations of Nondominated Sorting Genetic Algorithm
Authors: Kachhap Rakesh , Guria Chandan 
Published: July 2005

AbstractSummary: A multi‐objective optimization is carried out for a copoly(ethylene‐polyoxyethylene terephthalate) (CEPT) batch reactor using different adaptations of the elitist nondominated sorting genetic algorithm (NSGA‐II). Several two objective function problems are formulated and solved. One objective is to minimize the total copolymerization time and other objective is to minimize the formation of total undesirable side products, namely, acid end group, vinyl ester end group, diethylene glycol ester end group of polyethylene terephthalate, and diethylene glycol. End‐point constraint is incorporated to obtain the specified number‐average degree of copolymerization. The operating temperature history of batch CEPT reactor is the only important decision variable for first optimization problem, whereas operating temperature history and molar ratio of feed to the reactor are taken as decision variables for the second optimization problem. Optimal Pareto frontiers are obtained for both the problems studied. In order to operate the polymerization reactor optimally, it is found that higher isothermal temperature history is needed for short copolymerization time, whereas lower nonisothermal temperature history is required for higher copolymerization time. The results of NSGA‐II technique are analyzed and compared with the jumping gene (JG) and adapted jumping gene (aJG) operator in NSGA‐II separately. It is found that NSGA‐II‐JG is superior to NSGA‐II and NSGA‐II‐aJG.Optimization of a batch copoly(ethylene‐polyoxyethylene terephthalate) reactor.magnified imageOptimization of a batch copoly(ethylene‐polyoxyethylene terephthalate) reactor.
Optimal Control of Batch MMA Polymerization with Specified Time, Monomer Conversion, and Average Polymer Molecular Weights
Authors: Sundaram Baranitharan S. , Upreti Simant R. , Lohi Ali 
Published: July 2005

AbstractSummary: In this paper, the optimal control policies are determined for the free‐radical polymerization of methyl methacrylate (MMA) in a non‐isothermal batch reactor. The temperature of the fluid inside reactor‐jacket is used as the control function to realize four different optimal control objectives. Each objective is formulated to optimize a given variable simultaneously specifying another. The first two objectives target the maximization of monomer conversion in a specified operation time, and the minimization of operation time for a specified, final monomer conversion. The last two objectives target the maximization of monomer conversion for specified, final number‐ and weight‐average polymer molecular weights. The realization of these objectives is expected to be very useful for the batch production of polymers. To meet the specification of an optimization variable other than time, the differential model of batch process is expressed and utilized in the range of specified variable. Equations are provided for Jacobian evaluations to help in the accurate solution of process model. A genetic algorithms‐based optimal control method is applied to realize the four optimal control objectives. The results of this application show considerable improvements in the performance of batch MMA polymerization.
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Large time behaviour of solutions to Penrose–Fife phase change models
Authors: Feireisl Eduard , Schimperna Giulio 
Published: July 2005

AbstractA non‐conserved phase transition model of Penrose–Fife type is considered where Dirichlet boundary conditions for the temperature are taken. A sketch of the proof of existence and uniqueness of the solution is given. Then, the large time behaviour of such a solution is studied. By using the Simon–Łojasiewicz inequality it is shown that the whole solution trajectory converges to a single stationary state. Due to the non‐coercive character of the energy functional, the main difficulty in the proof is to control the large values of the temperature. This is achieved by means of non‐standard a priori estimates. Copyright © 2005 John Wiley & Sons, Ltd.
Design and characterization of a multimeric DNA binding protein using Sac7d and GCN4 as templates
Authors: Wu Sz‐Wei , Ko Tzu‐Ping , Chou Chia‐Cheng , Wang Andrew H.‐J. 
Published: July 2005

AbstractThe protein Sac7d belongs to a class of small chromosomal proteins from the hyperthermophilic archaeon Sulfolobus acidocaldarius. Sac7d is extremely stable to heat, acid, and chemical agents. This protein is a monomer and it binds DNA without any particular sequence preference, while inducing a sharp kink in the DNA. By appending a leucine‐zipper‐like helical peptide derived from the yeast transcriptional activator GCN4 to the C‐terminal end of Sac7d, the modified monomers (denoted S7dLZ) are expected to interact with each other via hydrophobic force to form a parallel dimer. The recombinant S7dLZ was expressed in Escherichia coli and purified by heating and ion‐exchange chromatography. The formation of dimer was detected by gel‐filtration chromatography and chemical cross‐link. The results of surface plasmon resonance and circular dichroism experiments showed that the DNA‐binding capacity was retained. Furthermore, X‐ray diffraction analysis of single crystals of S7dLZ in complex with DNA decamer CCTATATAGG showed that the leucine‐zipper segments of S7dLZ were associated into an antiparallel four‐helix bundle. There are two DNA fragments bound to each S7dLZ tetramer in the crystal. This model works as a successful template that endows protein a new function without losing original properties. Proteins 2005. © 2005 Wiley‐Liss, Inc.
An Adaptive Sequential Procedure for Efficient Optimization of the Sheet Metal Spinning Process
Authors: Henkenjohann Nadine , Göbel Roland , Kleiner Matthias , Kunert Joachim 
Published: July 2005

AbstractDue to technological advances in science, the complexity of processes under investigation increased continuously in recent years. For example, in mechanical engineering, there are often highly nonlinear input–output relationships combined with a large number of constraints. Sheet metal spinning is one example of such a production process. Many flexible and powerful methods to global optimization have been developed. In this paper, a sequential approach originally developed for computer experiments will be adopted and applied to optimize the spinning process based on physical experiments. This approach sequentially refines the model by adding new design points based on the expected improvement criterion. This criterion balances the need to observe at the predicted optimum with the need to investigate the design space in areas of high uncertainty. However to guarantee an efficient optimization of the spinning process, this approach has to be embedded in a more substantial procedure. One reason for this is the liability of workpiece failure for most of the operable design space. Since the shape of the failure region is unknown, many missing observations have to be expected when exploring the design space. The other reason is the need to incorporate available process knowledge of sheet metal spinning to improve the efficiency in optimization. The main problem in implementing this information is a changing process behavior for different geometries and materials used. Hence, if a component with a new geometry has to be optimized, it is difficult to include available process knowledge. In this paper, an adaptive sequential optimization procedure (ASOP) is presented to cope with these problems in order to guarantee an efficient optimization of such complex processes. The approach is exemplified by optimizing the spinning process for a fixed geometry. Copyright © 2005 John Wiley & Sons, Ltd.
Using Evolutionary Operation to Improve Yield in Biotechnological Processes
Authors: Kvist Trine , Thyregod Peter 
Published: July 2005

AbstractIn the biotechnological industry, production is often characterized by relatively few larger batches. In the design stages of a new process, the use of statistical methods for experimentation can provide invaluable information about the process. However, it is frequently found that optimum conditions in the laboratory or pilot plant give lower yields when transferred to full‐scale production. This fact is due to scale‐up effects and to the large inherent variations when dealing with biological material and processes such as fermentation. In full‐scale production there is not the same freedom to experimentation as at the laboratory scale. Simple one factor at a time trials are predominant when attempting to improve the yield at the production scale. In this way it is possible to control the outcome such that it still meets the requirements. However, this is a very inefficient way to perform experiments. The requirements for an alternative experimental procedure is that it should be robust to non‐controllable variations, it should contain automatic safeguards to ensure that unsatisfactory material is not manufactured and it should be possible to make decisions during the trial. Furthermore, it is important that the planning stage is short and the interpretation straightforward. The method of evolutionary operation (EVOP) suggested by George Box fulfilled these requirements. We present the implementation of EVOP in a major Danish biotechnological company. An example is presented where the method was used in the fermentation process of an industrial enzyme. In the particular example, process yield was improved by 45%. Copyright © 2005 John Wiley & Sons, Ltd.
Process Improvement in the Microelectronic Industry by State Space Modelling
Authors: Triantafyllopoulos K. , Godolphin J. D. , Godolphin E. J. 
Published: July 2005

AbstractThe exponentially weighted moving average (EWMA) model can be applied to a process controlling the thickness of nitride layers in the manufacture of microelectronic devices, involving the standard use of the notions of EWMA control chart, EWMA full adjustment and EWMA deadband adjustment charts for process monitoring and process improvement. We suggest that a dynamic step forward to process improvement is gained by considering basic state space models, which are known as local‐level models. The EWMA predictor is a limiting form of forecast for the local‐level model, so we propose replacing the EWMA by a local‐level model and thus develop feedback adjustment schemes. Under Gaussian assumptions, the entire forecast distribution is obtained routinely. A detailed development of the proposed state space adjustment scheme is given to the nitride layers process and a number of conclusions and recommendations are made. The proposed scheme is found to perform better than the EWMA if there is evidence of a shift in the level of the output process. Copyright © 2005 John Wiley & Sons, Ltd.
Statistical Modelling of MOS Transistor Mismatch for High‐voltage CMOS Processes
Authors: Posch Werner , Enichlmair Hubert , Schirgi Eduard , Rappitsch Gerhard 
Published: July 2005

AbstractThe random mismatch of semiconductor devices caused by local variations of the production process strongly influences critical performance parameters of analog circuits. In order to estimate the influence of the device mismatch on the circuit yield during the design phase, statistical mismatch models for the individual components must be provided for circuit simulation. Based on extensive statistical measurements of matched pairs using special test structures, an algorithm is presented to extract device mismatch parameters for high‐voltage transistors. Due to the special construction of high‐voltage transistors the mismatch parameters must be determined in two steps taking into account the effect of the drift region at high gate voltages. Therefore, the device mismatch for the threshold voltage, the gain factor and the mobility reduction are extracted from a sensitivity model in saturation, whereas the extraction of the drift‐resistance mismatch uses a modified MOS transistor model in the ohmic region. Based on the mismatch parameters for several device sizes a proper geometric model is extracted allowing the mismatch parameters to be scaled with the device dimensions. The mismatch parameters are implemented as part of circuit simulation model libraries to be used for Monte Carlo simulation. Production control parameters enable the monitoring of device mismatch for high‐voltage CMOS transistors. Copyright © 2005 John Wiley & Sons, Ltd.
Analysis of Split‐plot Designs with Mirror Image Pairs as Sub‐plots
Authors: Tyssedal John , Kulahci Murat 
Published: July 2005

AbstractIn this article we present a procedure to analyze split‐plot experiments with mirror image pairs as sub‐plots when third‐ and higher‐order interactions can be assumed negligible. Although performing a design in a split‐plot manner induces correlation among observations, we show that with such designs the essential search for potentially active factors can be done in two steps using ordinary least squares. The suggested procedure is tested out on a real example and on two simulated screening examples; one with a split‐plot design based on a geometric design and one with a split‐plot design based on a non‐geometric Plackett and Burman design. The examples also illustrate the advantage of using non‐geometric designs where the effects are partially aliased instead of being fully aliased as in highly fractionated fractional factorials. Copyright © 2005 John Wiley & Sons, Ltd.
Ab initio calculation of the interaction energy in the P2 binding pocket of HIV‐1 protease
Authors: Nivesanond Kanda , Peeters Anik , Lamoen Dirk , Van Alsenoy Christian 
Published: July 2005

AbstractInteractions at the P2 binding pocket of human immunodeficiency virus type 1 (HIV‐1) protease have been studied using calculated interaction energies for model systems that mimic this binding pocket. Models were built for the P2 pocket of HIV‐1 protease in complex with TMC114, nelfinavir, and amprenavir. A two‐step procedure was applied. In the first step, the size of the model system was confined to ∼40 atoms, and the interaction energy was calculated at different computational levels. In the second step, the size of the system was increased to 138 atoms, and the calculations were only performed at the HF/6‐31G** level. The interaction energy of the HIV‐1 protease/TMC114 complex was found to be more favorable than the interaction energies of the other complexes because of the additional hydrogen bond interaction this inhibitor is able to make with the HIV‐1 protease backbone. The results of the calculations are supported by stockholder charges and electrostatic potential maps. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Corner defects in almost planar interface propagation
Authors: Haragus Mariana , Scheel Arnd 
Published: July 2005

We study existence and stability of interfaces in reaction–diffusion systems which are asymptotically planar. The problem of existence of corners is reduced to an ordinary differential equation that can be viewed as the travelling-wave equation to a viscous conservation law or variants of the Kuramoto–Sivashinsky equation. The corner typically, but not always, points in the direction opposite to the direction of propagation. For the existence and stability problem, we rely on a spatial dynamics formulation with an appropriate equivariant parameterization for relative equilibria.

Résumé
Nous étudions l'existence et la stabilité des interfaces asymptotiquement planes dans des systèmes de réaction–diffusion. Le problème de l'existence des défauts est réduit à l'étude d'une équation différentielle ordinaire qui est, selon le cas, approchée par l'équation stationnaire d'une loi de conservation scalaire ou d'une variante de l'équation de Kuramoto–Sivashinsky. Typiquement, les défauts pointent dans la direction opposée à la direction de propagation. Pour l'analyse des problèmes d'existence et de stabilité, nous utilisons une formulation de type dynamique spatiale combinée avec une paramétrisation adéquate d'équilibres relatifs.
The effects of the interactions between amino acids on pyruvate kinase activity from the brain cortex of young rats
Authors: Feksa Luciane Rosa , Cornelio Andrea , Dutra‐Filho Carlos Severo , de Souza Wyse Angela Terezinha , Wajner Moacir , Wannmacher Clovis Milton Duval 
Published: July 2005

AbstractConsidering that pyruvate kinase activity, a crucial enzyme for glucose metabolism and energy liberation in brain, may be regulated by some amino acids, it is possible that diminution of this enzyme activity may contribute to the brain damage caused by amino acids accumulated in metabolic diseases, such as phenylalanine, tryptophan and cystine. Therefore, the present study was undertaken to investigate the effect of these amino acids on pyruvate kinase activity in the brain cortex of rats. We also investigated the effect of serine and alanine on pyruvate kinase activity in the same tissue. The results suggested that phenylalanine, tryptophan, cystine, alanine, and serine act at the same site on the enzyme, phenylalanine, tryptophan, and cystine causing inhibition, and alanine and serine preventing this effect. Cystine also inhibited the enzyme activity through a different mechanism, possibly acting on the enzyme thiol groups. Considering that this enzyme is a target for amino acids accumulated in some metabolic diseases of amino acid metabolism, it is possible that its inhibition may contribute to the brain damage found in these diseases.
An exploratory study of ‘close’ supplier–manufacturer relationships
Authors: Goffin Keith , Lemke Fred , Szwejczewski Marek 
Published: July 2005

AbstractClose relationships with selected suppliers can enable manufacturers to reduce costs, improve quality and enhance new product development. Although the advantages of close co‐operation are widely acknowledged in the literature, the specific attributes of such relationships are not well understood. To address this gap, 39 managers responsible for purchasing were interviewed using a technique from psychology, which is particularly effective at uncovering the characteristics of relationships. This approach is innovative in the context of supplier management research and gave insights into how manufacturers expect more from their suppliers than just reliable deliveries of high‐quality, well‐priced parts and components. The results of the empirical research enhance our knowledge of the attributes of manufacturer–supplier relationships and also indicate how manufacturers can establish close relationships with selected suppliers. Overall, the study has established the viability of a new approach for understanding the complex topic of manufacturer–supplier partnerships.
Management of the Vertebral Artery at the Craniocervical Junction
Authors: Çokkeser YasLar , Naguib Maged B. , Kizilay Ahmet 
Published: July 2005

OBJECTIVES:To study the surgical anatomy of the vertebral artery at the craniocervical junction and its related structures defining reliable landmarks for its safe exposure.DESIGN:Ten sides of 5 fresh cadavers were dissected using the lateral approach to the craniocervical junction.RESULTS:Experience gained in studying the anatomic details of the vertebral artery at the craniocervical junction in cadavers from its exit at the transverse foramen of the second cervical vertebra to the vertebrobasilar junction provided the initial background for us to use the lateral approaches to the skull base to safely manage 4 cases with pathology reaching the close vicinity of vertebral artery at the craniocervical junction.CONCLUSION:Thorough knowledge of the anatomy of the vertebral artery is mandatory before attempting surgery at the craniocervical junction. There are reliable landmarks that, when followed, could facilitate safe exposure and identification of the artery.