bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phase behavior of polymer blends under equilibrium and nonequilibrium conditions
Authors: Kammer Hans W. 
Published: March 2011

AbstractThis contribution embraces two topics related to phase behavior of polymer blends under equilibrium and nonequilibrium. 1. Polymer blends can undergo different phase changes as liquid‐liquid phase transition and crystallization. Coupling of demixing and crystallization may occur at the kinetic stage. This is illustrated by blends of poly(ϵ‐caprolactone)(PCL) and poly(styrene‐co‐acrylonitrile)(SAN). 2. Extension of studies to blend systems under flow is necessary for the better understanding of structure formation in polymer blends outside equilibrium. Polymer molecules will be oriented and stretched when subjected to flow. This may result in flow‐induced phenomena. Effects of flow on the phase behavior have been studied only for a few blends, as yet. The primary observation was flow‐induced miscibility. Apparent shifts of the phase transition temperatures will be discussed qualitatively in terms of a decoupled mode theory.
Phase separation studies on poly(vinylidene fluoride) and poly(methyl methacrylate) quenched blends
Authors: Martínez‐Salazar J. , Canalda J. C. , Vallejo B. 
Published: March 2011

AbstractA combined study by SAXS and DSC on quenched blends of PVDF and PMMA is presented. Attention is focused on the first stage of the phase separation process during annealing that is shown to be mainly determined by the diffusion of the PVDF molecules from the amorphous blend phase towards the crystals growth front. The experimental monomer diffusion constants at T > Tg are compared with those expected theoretically using the approximation of the fast model process and the WLF equation for the relaxation frequency of the monomer. The nature and composition of the crystal interphase are discussed in terms of the SAXS invariant for the whole system and the calorimetric data derived from the Tg transitions observed.
Plastic deformation of polymer blends with crystallizable components
Authors: Galeski Andrzej 
Published: March 2011

AbstractThe application of polymer blends depends mostly on their high ability to plastic deformation. Usually the studies of plastic deformation behavior include only the stress‐deformation relationship and investigation of changes of morphology of the blends on the size level of inclusions. The energy absorption is also often considered. The presented, more rigorous, approach to plastic deformation of polymer blends containing a crystallizable component involves the studies of crystal plasticity and associated deformation of the amorphous phase. Plastic deformation of blends containing high‐density polyethylene and isotactic poly(propylene) with other components were studied in two modes of deformation: 1. that avoids internal cavitation and 2. in tension with intense voiding. When no internal cavitation was involved, the plastic deformation was crystallographic in nature while the amorphous phase deformed in a manner to accommodate for the rotation and slips of the crystalline phase. Also the plastic deformation associated with intense voiding leads to a preferred orientation of certain crystallographic planes containing macromolecular chains which strongly suggests that the leading mechanisms in plastic deformation of blends are of crystallographic nature. The plastic deformation behavior depends very much on the glass transition of the amorphous component of the blend.
Polymer dynamics in random media, replica theory, ternary polymer systems: Mappings and equivalences
Authors: Ebert Ute , Schäfer Lothar 
Published: March 2011

AbstractFor polymer dynamics in quenched random media a renormalizability proof is lacking and calculations are lengthy. We here propose and define the static and the ergodic limit of the dynamic theory, and show, that these limits are equivalent to well‐known renormalizable static polymer theories. This procedure supplies us with a renormalizable substructure and puts the 2 loop analysis of the full theory within reach.
The glass transition in polymer melts
Authors: Baschnagel Jörg , Lobe Bernhard 
Published: March 2011

AbstractThis paper presents some results of a Monte Carlo simulation for the glass transition in two‐ and three‐dimensional polymer melts. The melt was simulated by the bond‐fluctuation model on a d‐dimensional cubic lattice which was combined with a two‐level hamiltonian favouring long bonds in order to generate a competition between the energetic and topological constraints in the system. This competition prevents crystallization and makes the melt freeze in an amorphous structure as soon as the internal relaxation times match the observation time of the simulation set by the cooling rate. The freezing point of the melt, i.e the glass transition temperature Tg, thus depends upon the cooling rate and additionally upon the chain length of the polymers. The dependence of the glass transition temperature on the cooling rate was closely analysed in three and that on the chain length in both two and three dimensions, resulting in a non‐linear relationship between Tg and the logarithm of the cooling rate and a linear relationship between Tg and the inverse chain length, respectively. In addition to this behaviour of the melt during the cooling process an example for the relaxational properties of the three‐dimensional model is provided by a quantitative analysis of the incoherent intermediate scattering function in the framework of the idealized mode coupling theory.
Flow‐alignment and rheology of polymer melts: Computation of the single‐link orientational distribution function
Authors: Kröger Martin 
Published: March 2011

AbstractThe single‐link orientational distribution function and the space‐averaged stresses in the fluid are computed for the case of steady shear flow of polymer melts. The computation is achieved with Galerkin's method with spherical harmonics and Euler polynomials as trial functions. The stress components become power functions of shear rate when the latter is large. The single‐link orientational distribution function f solves the Fokker‐Planck equation subject to a boundary condition for f at the chain ends. A solution is obtained for every shear rate and ratio of the orientational and one‐dimensional diffusion coefficient. It is demonstrated that the Fokker‐Planck equation with appropriate boundary condition is useful in order to predict the flow‐alignment and stresses in good agreement with experimental data as well as with recent results of a nonequilibrium molecular dynamics computer simulation on polymer melts.
Structural properties and swelling behavior of randomly crosslinked polymer networks: A monte carlo study
Authors: Sommer Jens‐Uwe 
Published: March 2011

AbstractThe structural properties as well as some aspects of the swelling behavior of randomly crosslinked polymer networks obtained by lattice Monte Carlo simulations are investigated.For a crosslink density of about 10 crosslink points per precursor chain, unusual structural properties are observable on scales well beyond the mesh size. For scales of order of the averaged mesh size an inner dimension of di ≅ 1.15 and for scales up to the lattice size di ⋍ 2.2 can be obtained. For the autocorrelation function of a random walker placed on the network topology, these properties can be reproduced.In the case of athermal swelling of the network structure inhomogeneous deformation of the individual network chains can be observed. Additionally the average network chain deformation is considerably less than the macroscopic swelling ratio.The swelling pressure of the network shows a scaling behavior different from the corresponding uncrosslinked system. This can be related to the fractal properties of the network within the correlation length by applying the well known scaling theory for the osmotic pressure for semidiluted polymers to fractal objects. This explains the swelling anomalies for polymer network even in the case of athermal swelling.
Polymer adsorption on heterogeneous surfaces
Authors: van Der Linden Catharina C. , Leermakers Frans A. M. 
Published: March 2011

AbstractThe adsorption of polymers on an energetically heterogeneous surface can be modelled using a self‐consistent field lattice theory. The surface consists of sites having different adsorption energies. It turns out that the distribution of the sites over the surface is one of the main parameters determining the adsorption behaviour.
New copolymers of vinylidene fluoride
Authors: Tournut Claude 
Published: March 2011

AbstractAfter a brief presentation of the standard non‐functionalized copolymers of vinylidene fluoride, the preparation of new functionalized copolymers is described, by copolymerization of vinylidene fluoride, with other fluoromonomers and non‐fluorinated monomers including at least one hydroxy or other functional group. The copolymers are analysed by the conventional methods. Examples of formulation show that these new copolymers are able to give coatings applicable outdoors and offering the same excellent durability as PVDF.
Surface active fluorosilicone polymers
Authors: Owen Michael J. , Kobayashi Hideki 
Published: March 2011

AbstractThe introduction of low‐intermolecular‐force, aliphatic fluorocarbon groups into siloxane polymers has produced a variety of useful, low surface tension materials including Rf(CH2)2SiO3/2 self‐assembled polymer monolayers and silsesquioxane polymers, and [Rf(CH2)2MeSiO]n siloxanes. The surface tensions of such materials measured by the contact angle approaches of Owens‐Wendt and Girifalco‐Good‐Fowkes‐Young are reviewed and compared with the direct determination from work of adhesion studies based on the Johnson, Kendall and Roberts theory. The lowest surface tension fluorosilicones available are as oleophobic and hydrophobic as any known fluoropolymer. The most efficient, effective incorporation of fluorine in these fluorosilicones is generally achieved with the CF3(CF2)3(CH2)2 group, making these nonafluorohexyl‐containing species the most commercially attractive.
A biodegradable material for ACL reconstruction
Authors: Gisselfält Katrin , Flodin Per 
Published: March 2011

AbstractBiodegradable polyurethane urea fibers for ACL reconstruction have been produced by wet spinning. By using a short‐chain polyester diol as the soft segment in the polyurethane urea the elongation‐to‐break of the fibers have been reduced to be below 100% instead of 400–800% for spandex fibers, the modulus is increased from 5 MPa to 1 GPa and the tensile strength is increased from 0.1 N/tex to 0.4 N/tex. The composition of the polyester determines at which rate the fiber degrade. Different polyesters have been investigated to find the most suitable degradation rate for ACL application.
Biological basis of enzyme‐catalyzed polyester degradation: 59 C‐terminal amino acids of poly(3‐hydroxybutyrate) (PHB) depolymerase a from pseudomonas lemoignei are sufficient for PHB binding
Authors: Briese Bernd Holger , Jendrossek Dieter 
Published: March 2011

AbstractBiodegradable polyesters such as biologically produced poly[(R)‐3‐hydroxybutyric acid], (PHB) other polyhydroxyalkanoic acids and related chemosynthetic polyesters have attracted industrial interest, and bacterial produced PHB is commercially available since 1990. A large variety of polyester degrading microorganisms have been found to be present in environment. The microorganisms decompose the polymers by secretion of extracellular polyester depolymerases and utilize low molecular weight degradation products for growth. Microbial polyester depolymerases have the unique property to be water soluble and to be able to bind specifically to polyester surfaces. The objective of this contribution is a functional analysis of a bacterial PHB depolymerase polyester binding domain. In addition, a detailed summary of the present knowledge on the biochemistry of enzymatic polyester hydrolysis is provided.
Biodegradable liquid‐crystalline aromatic polyesters
Authors: Kricheldorf Hans R. , Wahlen Lars , Stukenbrook Thomas 
Published: March 2011

AbstractTwo strategies designed for the mechanical reinforcement of biodegradable polyesters, such as poly‐(ε‐caprolactone), poly (L‐lactide) and their copolyesters, are described. Both strategies utilize more or less biodegradable thermotropic aromatic polyesters as reinforcing component. However, the structures of the aromatic polyesters differ largely. For strategy I polyesters composed of substituted hydroquinones and substituted terephthalic acids are used (which may contain anhydride groups), whereas the polyesters of strategy II are made up of natural nontoxic monomers such as β‐(4‐hydroxyphenyl) propionic acid and 4‐hydroxybenzoic acid.
Local dynamics and glass transition
Authors: Erman Burak , Bahar Ivet 
Published: March 2011

AbstractThe dynamics of polymer chains in the bulk state are discussed at three different temperature scales: (i) Well above the glass transition temperature where the basic step of motion is the rotameric transition of bonds. In this regime, the dynamics may conveniently be analyzed by the rotational isomeric state model, (ii) In the vicinity of glass transition where friction forces from the environment dominate. In this regime, the dynamics may be modeled according to the cooperative kinematics model, (iii) Well below glass transition. Here, an analogy with a native protein is made, and the mean‐squared fluctuations are analyzed by adopting the Gaussian Network Model, which recently proved successful in describing fluctuations in native proteins.
Combined assimilation of screen‐level observations and radar‐derived precipitation for soil moisture analysis
Authors: Mahfouf Jean‐François , Bližňák Vojtěch 
Published: March 2011

AbstractA methodology is proposed in order to combine information from radar precipitation with other observations (e.g. screen‐level temperature and relative humidity) in a soil analysis scheme based on an extended Kalman filter. A preliminary study is performed over the Czech Republic for one month in July 2008 using three‐hour rainfall accumulations derived from two C‐band radars and a land‐surface scheme forced by short‐range forecasts from a limited‐area model. The Jacobian matrix of the observation operator is examined to make optimal choices for the estimation of the Kalman gain matrix. It is shown that the size of the perturbation for computing Jacobian matrix elements with finite differences has to be carefully chosen, since too small values lead to unphysical negative elements whereas too large values reduce the spatial variability considerably. After a log‐transform of the precipitation field, the corresponding errors are more compatible with the Gaussian hypothesis of the Kalman filter. However, at locations where model rainfall is underestimated, positive soil moisture increments are much too low. Finally, two methods for combining the assimilation of screen‐level observations with radar precipitation are compared. A first evaluation shows more accurate soil analyses (leading to reduced screen‐level parameter forecast errors) when both sources of information are considered to correct soil moisture contents. Avenues for improving the specification of observation and model errors of the precipitation field are also discussed. Copyright © 2011 Royal Meteorological Society
Exohedral functionalization of fullerenes and supramolecular chemistry
Authors: Nakamura Yosuke , Kato Shin‐Ichiro 
Published: March 2011

AbstractWe have investigated the exohedral functionalization of [60]fullerene, especially bisaddition; we have revealed the regioselectivity of bisaddition and the properties of obtained bisadducts. The bisaddition without any restriction generally shows low regioselectivity. The electronic and photophysical properties of bisadducts mainly depend on the addition patterns and are almost independent of the nature of addends. We have also attained the regioselective synthesis of bisadducts by controlling the distance and orientation between two reactive species with suitable covalent templates and their application into some functional materials. The synthesis of fullerene‐containing interlocked molecules, such as catenanes and rotaxanes, was accomplished by using a noncovalent interaction, mainly a donor‐acceptor interaction, in addition to the covalent functionalization. The bistable rotaxanes, which can serve as a molecular shuttle or switch, were also successfully prepared. DOI 10.1002/tcr.201000036
Postgenomic technologies targeting the Wnt signaling network
Authors: Pancratov Raluca , DasGupta Ramanuj 
Published: March 2011

AbstractThe recent development of high‐throughput sequencing technologies and the availability of whole genome sequences of a variety of living organisms, including that of humans, have led to an enormous push in the quest for a comprehensive inquiry for the function of each and every gene discovered in different model organisms. A major conclusion from the sequencing projects was that while forward genetics had been extremely successful in identifying key genes/components of many biological processes, such as signal transduction cascades, the function(s) of the majority of genes in the genome remains a mystery. In this article, we discuss the use of a variety of high‐throughput postgenomic tools, including functional genomics, proteomics, and chemical genetics that are being implemented in an exhaustive molecular dissection of a key evolutionarily conserved signal transduction pathway, namely the Wnt/wingless (wg) pathway and its associated signaling network. WIREs Syst Biol Med 2011 3 649–665 DOI: 10.1002/wsbm.140This article is categorized under:

Laboratory Methods and Technologies > Genetic/Genomic Methods
Evolution and Development of Surgery for Large Paraesophageal Hiatus Hernia
Authors: Watson David I. 
Published: March 2011

AbstractLaparoscopic repair is the standard surgical approach to the problem of large paraesophageal hiatus hernia. It is associated with low risks of morbidity and mortality, although there is a small risk (less than 5%) of a clinically significant recurrent hernia. Various techniques have been proposed to minimise this risk, including esophageal lengthening procedures and mesh reinforcement of the hiatus. Both remain controversial. Radiological outcomes from randomised trials suggest that a reduction in hernia recurrence rates can be achieved with the use of mesh repair, although these trials have not demonstrated any clinically significant benefits for mesh repair. The risk of complications following mesh placement at the esophageal hiatus or an esophageal lengthening procedure needs to be balanced against potential benefits. More work is required to define the optimal approach to repair of large paraesophageal hiatus hernias.
Surface Microtextures of Quartz Grains from the Central Coast of Tamil Nadu
Authors: P. Udayaganesan , N. Angusamy , A. R. Gujar , G. V. Rajamanickam 
Published: March 2011

Abstract
Quartz grain surface micro textures of 12 samples collected from the beach were examined under scanning electron microscopy to understand the role of coastal processes on their transportation and deposition. The study area has been divided into three sectors on the basis of drainage, geomorphology and nature of the beach and shelf topography. Surface textures of the northern sector display an array of mechanical features like conchoidal fracture, V marks and impact pits, indicating the dominance of mechanical processes. However, silica precipitation in the form of globules indicates an added influence of chemical processes in the Northern sector. The presence of chemical features in northern sector, where energy level is high, corroborates the addition of quartz grains from paleo-sediments, from the nearby Tertiary and Cretaceous formations. Central sector quartz grains display the signatures of chemical and mechanical processes. The presence of step like furrows in southern sector is an indicator of fluvial low energy conditions, and supplements the role of littoral currents in depositing the quartz grains along the coastal region.
Embrayages narratifs en philosophie cartésienne
Authors: Méthot Jean-François 
Published: March 2011

RÉSUMÉNous examinons la narrativité du discours cartésien pour entamer un exercice herméneutique qui met en évidence quelques aspects des récits cartésiens, et qui montre que loin d’être un procédé littéraire, ou un simple agrément, le récit cartésien joue un rôle d’embrayeur au plan de la conceptualisation et de l’argumentation. La narrativité cartésienne met en jeu une double mimêsis qui est rétrospective dans les textes métaphysiques, et prospective dans les textes scientifiques. Ces deux directions remplissent des fonctions épistémologiques différentes.
Matérialisme et unité de l’être humain : le défi du dualisme cartésien chez La Mettrie et d’Holbach
Authors: Dumouchel Daniel 
Published: March 2011

RÉSUMÉLe présent article se propose de réfléchir sur le rôle que joue la pensée philosophique de Descartes chez deux des principaux philosophes matérialistes du xviiie siècle, Julien Offray de La Mettrie et le baron d’Holbach. Alors que les deux philosophes s’entendent sur le caractère aberrant et inintelligible de la spiritualité de l’âme, l’interprétation qu’ils font de la signification des conséquences du cartésianisme diffère. Tandis que l’auteur de L’homme-machine feint de voir dans le dualisme cartésien une ruse destinée aux théologiens, qui cache un matérialisme souterrain qui ne révélerait sa véritable portée que dans l’analogie de la machine appliquée à l’être humain, l’auteur du Système de la nature élève l’erreur cartésienne au rang d’emblème de l’ignorance philosophique causée par l’autonomisation de l’imagination théorique.
Lighting the route to success
Authors: Shetach Ana 
Published: March 2011

PurposeThis paper aims to provide team‐leaders and project managers with a practical and easily‐applicable managerial tool for coping with the large number of obstacles that may stand in the way to obtaining effective, efficient and altogether successful results, in overall management processes of projects and decisions within teams.Design/methodology/approachRelying on two previously published managerial tools, the “revised decision square model” and the “capi” model, this paper proceeds to present an integrated model, the team managerial coping flowchart, for the successful handling of team assignments and projects, towards the management of effective and efficient team decision making and implementation processes over time.FindingsThe paper relies on testimonies of managers who have adopted the proposed strategy for their every‐day use.Practical implicationsThe model offers a practical step‐by‐step set of guidelines, to lead managers towards a relatively high level of control in the management of effective and efficient team decision making and implementation processes, ensuring their route toward successful achievements.Originality/valueLimited attention has been given in the literature to the studying of practical and applicable managerial techniques to successful decision‐implementation in teams. The paper focuses on this neglected domain, proposing a solution in the form of an integrative strategy.