bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some industrial aspects of the suspension polymerisation process for making expandable polystyrene and the development of a polystyrene ‐ poly(methyl methacrylate) based system
Authors: Dequatre Claude , Duhamel Thierry , Hermant Anne , Pla Fernand 
Published: March 2011

AbstractThe main industrial concerns associated with the suspension polymerisation process for making expandable polystyrene are given and a polystyrene‐poly(methyl methacrylate) based system prepared by this process is described, characterized by transmission and scanning electron microscopy and glass transition temperature measurements.
Ring opening metathesis polymerization catalysts
Authors: Grubbs R. H. , Hillmyer M. , Li R. , Diaz E. , Nguyen S. T. 
Published: March 2011

AbstractOver the past eight years, early transition metal catalysts for the ring opening metathesis polymerization of cyclic olefins have been developed. These catalysts are simple organometallic complexes containing metal carbon multiple bonds that in most cases polymerize olefins by a living process. These catalysts have been used to prepare a family of near monodispersed and structurally homogeneous polymers. A series of group VIII ROMP catalysts that allow a wide range of functionality to be incorporated into the polymer side chains have recently been prepared. This most important members of this family of complexes are the bisphosphinedihaloruthenium carbene complexes. These catalysts show excellent functional group stability and can be used to prepare well defined telechelic polymers, polyolefins with ordered functionality, and highly functionalized block copolymers.
Synthesis of ultrathin polymer films by self assembly
Authors: Kunitake Toyoki 
Published: March 2011

AbstractRecent progresses in the self assembly of ultrathin polymer films are described. Bilayer membranes of polymeric hydrogen‐bond networks are formed in water. Two‐dimensional networks of organic and inorganic polymers are formed in cast films of synthetic bilayer membranes to give stable multilayer films upon removal of the matrices. The monolayer at the air‐water interface constitutes suitable templates for 2D polymer networks, and it may be either removed or part of the 2D film. Successive adsorption of polycations and polyanions under carefully controlled conditions produces layered polyion complexes in the stepwise manner. Various polymer chains are epitaxially adsorbed onto graphite. All these results indicate that molecularly defined 2D polymer structures are readily available.
Detailed mechanism of radical high polymerization of sterically hindered dialkyl fumarates
Authors: Matsumoto Akikazu , Otsu Takayuki 
Published: March 2011

AbstractThe radical polymerization kinetics and mechanism of sterically hindered dialkyl fumarates (DRF) bearing various ester alkyl groups are described comprehensively. The overall polymerization reactivity of DRF, the initiation mechanism and the reactivity of the primary radicals in the polymerizations with azo initiators, the determination of the propagation and termination rate constants by means of electron spin resonance spectroscopy, the propagation mechanism and the microstructure of the polymers, and the chain rigidity of poly(DRF) and bimolecular termination process are discussed.
Titanium‐based lewis acids for living cationic polymerizations of vinyl ethers and styrene: Control of lewis acidity in design of initiating systems
Authors: Sawamoto Mitsuo , Kamigaito Masami 
Published: March 2011

AbstractThis brief account discusses the development of HCl/TiCl4‐n(OR)n (n = 1–4), the titanium‐based new initiating systems for living cationic polymerizations of vinyl ethers and styrene. The focus of this development is controlling the Lewis acidity of the metal halide components [TiCl4‐n(OR)n] or “activators” in relation to the structure of the monomers. Thus, for vinyl ethers, relatively mild Lewis acids such as TiCl(OiPr)3 and TiCl2(OiPr)2 are effective, whereas for styrene, a stronger Lewis acid such as TiCl3(OiPr) is employed along with an added salt (nBu4N+Cl−). In both cases, living polymers of controlled molecular weights can be obtained in methylene chloride solvent at −15°C.
Polymerizations with contribution of covalent and ionic species
Authors: Penczek Stanislaw , Szymanski Ryszard , Duda Andrzej 
Published: March 2011

AbstractThe similarities and dissimilarities between the ring‐opening and vinyl cationic polymerizations are discussed for systems with simultaneous presence of covalent and ionic species. The common denominator in comparing kinetics of polymerization of these systems is the comparison of the total times of polymerization with the time elapsing when a given macromolecule is active (i.e. ionic) and inactive (e.g. covalent in cationic vinyl and ring‐opening polymerization). In the cationic ring‐opening polymerization the reactivation of covalent species proceeds mostly by intramolecular nucleophilic dipole‐dipole reaction (conformationally assisted) involving the chain unit adjacent to growing ester chain end. This reaction is fast (e.g. in THF polymerization) and is responsible for covalent ion‐pair interconversion. In the cationic vinyl polymerization this path does not exist but covalent species (esters) can be faster ionized by using of the nucleophile, increasing thus the rate of exchange between esters and ions. This process provides one of the possible ways for converting the non‐living polymerization into the living‐dormant process. The cationic polymerizations are then compared with covalent (pseudoanionic) polymerization of cyclic esters, initiated with covalent metal alkoxides like R2AlOR' or Al(OR)3.
Hydrogen bonding and the self‐assembly of supramolecular liquid‐crystalline materials
Authors: Kato Takashi , Fréchet Jean M. J. 
Published: March 2011

AbstractNovel supramolecular liquid‐crystalline materials have been obtained by the hydrogen bond formation between different and independent molecules. The self‐assembly of carboxylic acid and pyridine moieties that function as H‐bond donors and acceptors, respectively, results in the formation of mesogenic complex structures. A wide variety of liquid‐crystalline low molecular weight complexes have been prepared using this approach. This concept has been extended to the polymeric systems. Hydrogen‐bonded liquid‐crystalline polymers that exhibit mesophases over wide temperature ranges, ferroelectricity or photo‐responsibility have been prepared by the molecular association. Moreover, liquid‐crystalline polymer networks that show reversible smectic‐isotropic phase transitions have been formed by the hydrogen bonds. The dynamics of the hydrogen bonding may contribute to the induction of the mesomorphism of the networks.
Design and synthesis of macromolecular structures from self‐assembling building blocks
Authors: van Nunen J. L. M. , Schenning A. P. H. J. , Hafkamp R. J. H. , van Nostrum C. F. , Feiters M. C. , Nolte R. J. M. 
Published: March 2011

AbstractThe self‐assembling properties of a variety of building‐blocks are used to generate different types of nanostructures, e.g. molecular golfballs, molecular tubes, and molecular braids.
Design, synthesis and properties of molecular composites of rod‐like polymers
Authors: Wegner Gerhard 
Published: March 2011

AbstractProcessing and performance of fiber reinforced polymers suffer from problems related to the heterogeneous nature of the composites. The strong impact of the nature of the interface between fibers and matrix adds to the complication of the field. Consequently many attempts have been made to reduce the cross‐section of the reinforcing fibers to molecular dimensions and to increase the compatibility between the rod‐like molecules or bundles of molecules and the isotropic matrix of ordinary flexible polymers. All such attempts have failed, mainly for reasons of thermodynamics which predict immiscibility of rods and coils on the molecular level. A possibility to create structures in which molecular rods are embedded in a continuous matrix of flexible chain segments exists nevertheless.1 Rod‐like backbone structures decorated with a skin of flexible side chains of moderate length in terms of the number of carbon atoms (typically C6 ‐ C18‐side chains) have been synthesized and tested for the spontaneous formation of molecular composites. Some of the materials built along this principle can be processed by solution casting or even melt extrusion. The academically more interesting materials can be built up layerwise by a modified Langmuir‐Blodgett technique. The latter process gives rise to monodomain textures which allow for straight‐forward testing of the mechanical properties by optical means (Brillouin‐spectroscopy) and by piezoquartz‐techniques.Hairy‐rod macromolecules can also be synthesized which contain crosslinkable side chains. Thus, after formation of layered, oriented structures, these can be crosslinked photochemically or by curing. The result is a network, which is unidirectionally reinforced by the rod‐like macromolecules. These novel types of networks can serve as membranes by which size exclusion is achieved via control of the distance between adjacent backbone molecules in the matrix. Recent synthetic advances in the field have concentrated on hairy‐rod macromolecules based on cellulose alkyl ethers and on derivatives of poly‐(p‐phenylene). The latter materials serve as examples of systems which can be processed by casting and extrusion processes. Due to their excellent thermal stability relevant data on the rheological and mechanical‐dynamical data have become available. These data serve to document the unique behavior of the hairy‐rod macromolecules as bulk materials.
Supramolecular devices for targeting dna into cells: Fundamentals and perspectives
Authors: Kabanov V. A. , Kabanov A. V. 
Published: March 2011

AbstractInteraction of DNA polyanions with polycations results in spontaneous electrostatic coupling of opposite charged macromolecules and formation of interpolyelectrolyte complexes (IPECs). If the appropriate conditions are met such complexes can be obtained in the form of equilibrated and well defined water‐soluble supramolecular (actually supramacromolecular) species. Soluble IPECs formed by coupling of cyclic DNA (plasmid DNA) with various polycations are found to be efficient devices enhencing plasmid penetration into intact cells, probably, due to increase of a membrane activity of the complexed DNA. The strategy based on certain fundamental properties of IPECs seems to be a general approach for effective targeting of a genetic material to cells not only in vitro but also in vivo. These properties including those of DNA containing IPECs as well as the representative examples of gene delivery using IPEC supramacromolecular devices are reviewed and discussed.
Self‐assembled networks of conducting polyaniline in bulk polymers: A new class of conducting polymer blends
Authors: Heeger Alan J. , Smith Paul , Cao Yong 
Published: March 2011

AbstractThis review of the current status of conducting polymers will focus on recent progress which demonstrates that the initial promise of the late 1970's has become reality. Conducting polymers are now available as materials with truly unique properties: They combine the important electronic and optical properties of semiconductors and metals with the attractive mechanical properties and processing advantages of polymers. Conducting polymer blends based upon polyaniline (PANI) are a new class of materials in which the threshold for the onset of electrical conductivity (σ) can be reduced to volume fractions below 1%, well below that required for classical percolation (16% by volume for globular conducting objects dispersed in an insulating matrix in three dimensions). The origin of this remarkably low threshold for the onset of electrical conductivity is the self‐assembled network morphology of the PANI polyblends which forms during the course of liquid‐liquid separation. Since the average density of the conducting network near threshold is small, the conductivity increases smoothly and continuously over many orders of magnitude as the concentration of conducting polymer increases above threshold. The low percolation threshold and the continuous increase of σ(f) above threshold are particularly important; as a result of this combination, conducting polyblends can be reproducibly fabricated with controlled levels of electrical conductivity while retaining the desired mechanical properties of the matrix polymer.1‐3)
High performance nonlinear optical chromophores
Authors: Shi R. F. , Yamada S. , Wu M. H. , Cai Y. M. , Zamani‐Khamiri O. , Garito A. F. 
Published: March 2011

AbstractBoth the linear and nonlinear optical properties of our newly designed high temperature electrooptic chromophores are discussed. In addition to the charge separated mechanism for the new chromophores, isomer effects are equally important in determining the optical properties of the new class.
Electrical field induced phase‐matched second harmonic generation in low Tg polymer waveguides
Authors: Watanabe T. , Zou D. , Mohamed B. , Usui H. , Miyata S. , Claude C. , Okamoto Y. 
Published: March 2011

AbstractSecond‐harmonic generation in the guided waveguide configuration is very attractive because a high fundamental power density can be coupled over long propagation length therefore remarkably high conversion efficiencies can be expected compared to bulk materials.1 Organic SHG devices in optical waveguides have not been developed extensively because of the difficulty encountered in phase‐matching. To avoid this problem, the use of an artificial periodic structure, Cerenkov radiation, and non‐colinear light path geometry have already been demonstrated. Recently, we reported an electric field‐induced dynamic phase‐matching in a guided wave configuration using a main‐chain polymer in which the effective phase‐matching thickness can be controlled by an applied electric field.2 This technique is able to increase the waveguide dimension tolerances of phase‐matching condition. In the case of a main‐chain polymer, the thermal optic effects due to the heating prevent to satisfy the optimum phase‐matching conditions, which causes a reduction in the conversion efficiency of devices. In order to overcome this problem, we have synthesized novel low glass transition temperature (Tg) nonlinear optical (NLO) polymers.In this presentation, we will discuss an electric field‐induced dynamic phase‐matching of a multilayer waveguide at room temperature using a low Tg NLO polymer which can increase both the waveguide dimension tolerances and overlap integral. Using this technique, efficient phase‐matched SHG was generated from p‐nitroaniline grafted NLO materials. The dimension tolerance of waveguides under an electric field will be described.
Large‐amplitude motion in polymer crystals and mesophases
Authors: Wunderlich Bernhard 
Published: March 2011

AbstractLarge‐amplitude motion of macromolecules involves mainly rotation about bonds (conformational motion). In the liquid phases, the large‐amplitude motion is coupled with disorder and accounts for the flow and viscoelastic behavior. Perfectly ordered crystals, in contrast, permit only little large‐amplitude motion. The mesophases are intermediate in order and mobility. In crystals, large‐amplitude motion leads initially to gauche defects and kinks (conformational defects), and ultimately may produce conformationally disordered crystals (condis crystals). Molecular dynamics simulations of crystals with up to 30 000 atoms have been carried out. They show the mechanism of defect formation, permit the study of the distribution of defects, and lead to a visualization of the hexagonal crystal phase. The main‐chain liquid‐crystalline macromolecules and condis crystals, the two mesophases of polymers, can be distinguished on the basis of an analysis of the phase separation (partial crystallinity), present in condis crystals and not in liquid crystals. Solid state NMR is the tool of choice for the detection of mobile and rigid phases. In highly drawn fibers one can find four different states of order and mobility. Besides the (defect) crystalline phase and the isotropic amorphous phase, an intermediate oriented phase and a rigid amorphous phase exist.
Anxiety rating scales in Parkinson's disease: A validation study of the Hamilton anxiety rating scale, the Beck anxiety inventory, and the hospital anxiety and depression scale
Authors: Leentjens Albert F.G. , Dujardin Kathy , Marsh Laura , Richard Irene H. , Starkstein Sergio E. , Martinez‐Martin Pablo 
Published: March 2011

AbstractBackground:Anxiety is a prevalent and disabling condition in Parkinson's disease (PD). The lack of anxiety rating scales validated for this population hampers research into anxiety in PD. The aim of this study is to assess the clinimetric properties of the Hamilton anxiety rating scale (HARS), the Beck anxiety inventory (BAI), and the hospital anxiety and depression scale (HADS) in PD patients.Design:Three hundred forty‐two PD patients underwent a standardized assessment including a structured interview for diagnostic and statistical manual diagnoses of anxiety disorders and completion of the HARS, BAI, and HADS. Inter‐rater reliability of the HARS was assessed in 60 patients; test‐retest reliability of the BAI and HADS in 213 and 217 patients, respectively.Results:Thirty‐four percent of patients suffered from an anxiety disorder, whereas an additional 11.4% had clinically significant anxiety symptoms in the absence of a diagnosis of anxiety disorder. Acceptability, score distribution, and known groups validity over different levels of anxiety were adequate. Inter‐rater reliability for the HARS and test‐retest reliability for the BAI and HADS were good. The HARS, but not the BAI and HADS, had a satisfactory inter‐item correlation, convergent validity and factorial structure. For all scales, the positive predictive value was poor, and the negative predictive value was moderate.Conclusions:Given the adequate known groups validity of all three rating scales, each of these scales is likely to be useful in clinical practice or research for evaluation of symptom severity. Limitations in the construct validity of the anxiety scales in this study raise questions regarding suitability for their use in PD. © 2011 Movement Disorder Society
Anorganische Chemie 2010
Authors: Fischer Roland C. , Weigand Jan J. , Wolf Robert , Rau Sven , Schatzschneider Ulrich 
Published: March 2011

AbstractMolekülchemie der Hauptgruppenelemente: Trends wie die Stabilisierung ungewöhnlicher Bindungsumgebungen durch Carbene, die Darstellung persistenter Radikale, neuartige komplexchemische Wirtsysteme und Cluster als Liganden setzen sich fort. Koordinationschemie: Neuartige Metall‐Metall‐Bindungen erregten große Aufmerksamkeit; der Trend, metallorganische Gerüstverbindungen als Reaktionsraum oder Modellsystem zu nutzen, setzt sich fort. Bioanorganik: Die Aktivierung kleiner Moleküle wie H2 und CH4 durch Metalloenzyme hielt letztes Jahr einige Überraschungen parat.
Organische Chemie 2010
Authors: Bräse Stefan 
Published: March 2011

AbstractStefan Bräse (Koordinator) et al.Die Highlights des Jahres: Funktionswerkstoffe für Solarzellen — Funktionalisierte Graphenbausteine — Kupfer in Kreuzkupplungen — Nobelpreis für Palladium‐Chemie — Palau'amin — AAT‐Bausteine für die Zuckerchemie.
Theoretische Chemie 2010
Authors: Auer Alexander , Kästner Johannes , Burghardt Irene 
Published: March 2011

AbstractTensorzerlegungen haben ein enormes Potenzial für effizientere Näherungen in der Quantenchemie. Bei QM/MM‐Ansätzen liegen heute die Herausforderungen darin, die vielen Freiheitsgrade realistisch zu behandeln. In der Quantendynamik werden angesichts der wachsenden Komplexität der untersuchten Systeme universell anwendbare Verfahren seltener.
Makromolekulare Chemie 2010
Authors: Luxenhofer Robert , Groll Jürgen , Schnieders Frank , Oenbrink Georg 
Published: March 2011

AbstractMakromoleküle lassen sich mit orthogonalen chemischen Reaktionen maßschneidern. Teilweise biologisch inspirierte Konzepte kombinieren Selbstanordnung mit Funktionalität. Hauptanwendungsgebiete funktionaler Makromoleküle sind Elektronik und Biomedizin.
Chemiedidaktik 2010
Authors: Becker Hans‐Jürgen , Hildebrandt Henry 
Published: March 2011

AbstractDie Wirtschaft stellt für die Förderung chemischer Bildungsprozesse derzeit enorme Ressourcen bereit. Eine chemiedidaktische Perspektive entwickelt sich erst allmählich, sie muss und kann an vorliegende Forschungen zum Verhältnis von Chemieunterricht und Wirtschaft anknüpfen.
An automated database case definition for serious bleeding related to oral anticoagulant use
Authors: Cunningham Andrew , Stein C. Michael , Chung Cecilia P. , Daugherty James R. , Smalley Walter E. , Ray Wayne A. 
Published: March 2011

ABSTRACTPurposeBleeding complications are a serious adverse effect of medications that prevent abnormal blood clotting. To facilitate epidemiologic investigations of bleeding complications, we developed and validated an automated database case definition for bleeding‐related hospitalizations.MethodsThe case definition utilized information from an in‐progress retrospective cohort study of warfarin‐related bleeding in Tennessee Medicaid enrollees 30 years of age or older. It identified inpatient stays during the study period of January 1990 to December 2005 with diagnoses and/or procedures that indicated a current episode of bleeding. The definition was validated by medical record review for a sample of 236 hospitalizations.ResultsWe reviewed 186 hospitalizations that had medical records with sufficient information for adjudication. Of these, 165 (89%, 95%CI: 83–92%) were clinically confirmed bleeding‐related hospitalizations. An additional 19 hospitalizations (10%, 7–15%) were adjudicated as possibly bleeding‐related. Of the 165 clinically confirmed bleeding‐related hospitalizations, the automated database and clinical definitions had concordant anatomical sites (gastrointestinal, cerebral, genitourinary, other) for 163 (99%, 96–100%). For those hospitalizations with sufficient information to distinguish between upper/lower gastrointestinal bleeding, the concordance was 89% (76–96%) for upper gastrointestinal sites and 91% (77–97%) for lower gastrointestinal sites.ConclusionA case definition for bleeding‐related hospitalizations suitable for automated databases had a positive predictive value of between 89% and 99% and could distinguish specific bleeding sites. Copyright © 2011 John Wiley & Sons, Ltd.
iTRAQ‐based proteomic study of the effects of microcystin‐LR on medaka fish liver
Authors: Malécot Mélodie , Marie Arul , Puiseux‐Dao Simone , Edery Marc 
Published: March 2011

AbstractMicrocystins are cyanotoxins that occur in ground water and thus pose a potential health risk. Microcystin‐LR (microcystin‐leucine‐arginine) is a potent hepatotoxin, and is suspected of being a tumour promoter. Poisoning with this toxin causes several dysfunctions in hepatocytes by inhibiting protein phosphatases 1 and 2A, and notably produces oxidative stress, disrupts the cytoskeleton, and deregulates mitogen‐activated protein kinase pathway. Medaka fish (Oryzias latipes) was chosen as a model for studying the effects of this cyanotoxin on liver proteins using a gel‐free approach, iTRAQ. Fish were gavaged with microcystin‐LR. Two hours later, 325 proteins could be identified by Scaffold Q+ and 32 proteins revealed statistically significant variations above a ∣0.2∣ threshold of log2 ratio by comparison with control. These proteins are mostly involved in the translation and maturation of proteins, lipid metabolism and detoxification. Notably, apolipoproteins are deregulated which indicates a possible alteration of chylomicron‐mediated transport.