bluuebunny/crossref_metadata_2025_split huggingface dataset:
A multicenter nationwide reference intervals study for common biochemical analytes in Turkey using Abbott analyzers
Authors: Ozarda Yesim , Ichihara Kiyoshi , Aslan Diler , Aybek Hulya , Ari Zeki , Taneli Fatma , Coker Canan , Akan Pinar , Sisman Ali Riza , Bahceci Onur , Sezgin Nurzen , Demir Meltem , Yucel Gultekin , Akbas Halide , Ozdem Sebahat , Polat Gurbuz , Erbagci Ayse Binnur , Orkmez Mustafa , Mete Nuriye , Evliyaoglu Osman , Kiyici Aysel , Vatansev Husamettin , Ozturk Bahadir , Yucel Dogan , Kayaalp Damla , Dogan Kubra , Pinar Asli , Gurbilek Mehmet , Cetinkaya Cigdem Damla , Akin Okhan , Serdar Muhittin , Kurt Ismail , Erdinc Selda , Kadicesme Ozgur , Ilhan Necip , Atali Dilek Sadak , Bakan Ebubekir , Polat Harun , Noyan Tevfik , Can Murat , Bedir Abdulkerim , Okuyucu Ali , Deger Orhan , Agac Suret , Ademoglu Evin , Kaya Ayşem , Nogay Turkan , Eren Nezaket , Dirican Melahat , Tuncer GulOzlem , Aykus Mehmet , Gunes Yeliz , Ozmen Sevda Unalli , Kawano Reo , Tezcan Sehavet , Demirpence Ozlem , Degirmen Elif 
Published: August 2014

AbstractA nationwide multicenter study was organized to establish reference intervals (RIs) in the Turkish population for 25 commonly tested biochemical analytes and to explore sources of variation in reference values, including regionality.Blood samples were collected nationwide in 28 laboratories from the seven regions (≥400 samples/region, 3066 in all). The sera were collectively analyzed in Uludag University in Bursa using Abbott reagents and analyzer. Reference materials were used for standardization of test results. After secondary exclusion using the latent abnormal values exclusion method, RIs were derived by a parametric method employing the modified Box-Cox formula and compared with the RIs by the non-parametric method. Three-level nested ANOVA was used to evaluate variations among sexes, ages and regions. Associations between test results and age, body mass index (BMI) and region were determined by multiple regression analysis (MRA).By ANOVA, differences of reference values among seven regions were significant in none of the 25 analytes. Significant sex-related and age-related differences were observed for 10 and seven analytes, respectively. MRA revealed BMI-related changes in results for uric acid, glucose, triglycerides, high-density lipoprotein (HDL)-cholesterol, alanine aminotransferase, and γ-glutamyltransferase. Their RIs were thus derived by applying stricter criteria excluding individuals with BMI >28 kg/mWith the lack of regional differences and the well-standardized status of test results, the RIs derived from this nationwide study can be used for the entire Turkish population.
Liquid crystalline elastomers as artificial muscles
Authors: Wermter Hendrik , Finkelmann Heino 
Published: August 2014

AbstractNew nematic co-elastomers were synthesized which consist of a combination of nematic side- and main-chain polymers and where the liquid crystalline main-chain polymer can be considered as a macromolecular crosslinking component. By applying a mechanical field during the crosslinking process, the director of the nematic phase becomes macroscopically uniformly aligned and liquid-single-crystal elastomers were obtained. Within a narrow temperature regime, these networks can change their shape in one dimension by a factor > 3 and considerably improve the ability of being used as artificial muscles or mechanical actuators compared to the well known nematic side-chain elastomers. Networks having a non-ordered polydomain structure exhibit “soft (or semi-soft) elasticity” which is not only determined by a director reorientation process. Obviously, hairpin conformations within the main-chain segments contribute to this effect.
Superlattices in block copolymer blends with attractive interactions
Authors: Markgraf Kirsten , Abetz Volker 
Published: August 2014

AbstractBlends of microphase separated polystyrene-block-polybutadiene-blockpoly( methacrylic acid) triblock copolymers (SBA) with polystyrene-block-poly(2- vinylpyridine) (SV) or poly(2-vinylpyridine)-block-poly(cyclohexyl methacrylate) (VC) diblock copolymers were prepared and characterized. Attractive segmental interactions through hydrogen bonds between A and V could be monitored by infrared spectroscopy and dynamic mechanical analysis. Common superlattices were obtained by casting from a mixed solution of these block copolymers in tetrahydrofuran and were investigated by transmission electron microscopy. Varying the amount of hydrogen bonding donors via controlled saponification of an SBT triblock copolymer (T: poly(tert-butyl methacrylate)) lead to different superlattices in blends with a VC diblock copolymer.
Hydrolysis of the Nafion® precursor studied by X-ray scattering and in-situ atomic force microscopy
Authors: Elliott James A. , James Paul J. , McMaster Terence J. , Newton John M. , Elliott Alice M. S. , Hanna Simon , Miles Mervyn J. 
Published: August 2014

AbstractThe hydrolysis of Nafion® † precursor material to a perfluorosulfonate ion exchange membrane has been studied in situ at the surface of a sample using atomic force microscopy (AFM), and in the bulk using a combination of small and wide-angle X-ray scattering. The AFM results show that there is a rapid and significant change in the surface morphology of the sample during the first 12 min after the introduction of aqueous hydroxyl ions, provided that an appropriate swelling agent is used. After this point there is little change in surface morphology, although bulk swelling of the sample continues. The wide-angle X-ray scattering results indicate a significant drop in the degree of crystallinity of fluorocarbon matrix from 14±1% to 7±1% on hydrolysis, as a result of the bulk structural reordering necessary to accommodate the formation of ionic clusters. Ionic clustering is confirmed by the appearance of a characteristic small-angle X-ray peak. However, the peak forms towards the end of the hydrolysis process, and subsequently coarsens, suggesting that the formation of ionic clusters is a slow process compared to the rate of hydrolysis. It is confirmed that an appropriate water/solvent mixture is necessary to achieve an efficient conversion of precursor to membrane. AFM images of the precursor surface, when water alone is used, show no signs of structural change.
Review: Progress in liquid crystal displays by new developments in functional polymers
Authors: Broer Dirk J. , Haaren Jos A. M. M. van , Bastiaansen Cees W. M. 
Published: August 2014

AbstractFunctional polymers have become essential in the functioning and performance of many products for information and communication technologies. Special polymers have been constructed with an accurate control over their morphology to a size down to the wavelength of light. These polymers improve liquid crystal displays on eye-catching properties like brightness and viewing angle. The improved energy efficiency is crucial for the mobile communication equipment in today’s information society.
Photoinitiated cationic polymerization using allylsulfonium salts. Substituent effect on the initiator activity
Authors: Bayramoglu Fatma , Onen Aysen , Yagci Yusuf 
Published: August 2014

AbstractAllylthiophenium salts with various substituents at the allylic moiety were synthesized, characterized and shown to be efficient coinitiators in radicallly promoted cationic photopolymerization of cyclohexene oxide. The relative efficiencies of these salts in combination with benzoin and benzophenone as free radical sources in the photopolymerizations are compared. Both additionfragmentation and electron transfer mechanisms are proposed and their relative merits discussed.
Effect of the dispersion of the chromophore on the optical performances of polarizers from polyethylene and 5”-thio- (3-butyl)nonyl-2,2’:5’,2”-terthiophene
Authors: Pucci Andrea , Moretto Letizia , Ruggeri Giacomo , Ciardelli Francesco 
Published: August 2014

AbstractA new polyethylene-compatible terthiophene chromophore, 5”-thio-(3- butyl)nonyl-2,2’:5’,2”-terthiophene, with melting point lower than 0°C was prepared and used for linear polarizers based on ultra-high-molecular-weight polyethylene (UHMWPE). Differential scanning calorimetry and scanning electron microscopy indicate that the new chromophore is dispersed uniformly in films of UHMWPE obtained by casting from solution. The films show excellent dichroic properties (dichroic ratio 30) at rather low drawing ratio (≈ 20) . Moreover, qualitative agreement is observed with the Ward pseudo-affine deformation scheme.
Deprotective activity of nanosized globular partially quaternized poly(tertiary amine)s in peptide synthesis
Authors: Chapon Pascal , Coudane Jean , Garreau Henri , Vert Michel , Ferhentz Jean Alain , Martinez Jean 
Published: August 2014

AbstractBifunctional polybases of the partially quaternized poly[thio-1-(N,Ndiethylaminomethyl) ethylene] type (Q(PTDAE),X, with X = percentage of N-quaternization) are able to catalyze various reactions including lipophilic reagents temporarily entrapped in the hydrophobic core of the globules. In this contribution it is shown that benzyloxycarbonyl (Z) and fluoromethyloxycarbonyl (Fmoc) protecting groups of peptides are cleaved at room temperature in a few minutes in an aqueous medium at pH 7,4. Deprotection was also effective when peptides were attached to solid supports of the Merrifield type provided a hydrophilic spacer arm of the poly(ethylene glycol)-type was inserted between beads and the built up peptide moieties. However, unhooking was observed when the hydrophilic spacerpeptide bond was an ester but not when it was of the amide type. The work shows that Q(PTDAE),X globules exhibit enzyme-like activity in a homogeneous aqueous medium and in heterogeneous systems as well.
Sodium nitrite and ascorbic acid: a metal-free combination that controls the free-radical polymerization of tert-butyl methacrylate in water
Authors: Detrembleur Christophe , Mouithys-Mickalad Ange , Teyssié Philippe , Jérôme Robert 
Published: August 2014

AbstractA mixture of sodium nitrite and ascorbic acid is able to control the radical polymerization of tert-butyl methacrylate (tBMA) in water at 80°C. Indeed, sodium nitrite is reduced by the ascorbic acid, and the nitric oxide (NO) which is formed insitu is nothing but a promoter of nitroxyl radicals. The radical polymerization of tBMA is thus basically controlled by a nitroxide-mediated process.
Cyclodextrins in polymer synthesis: Dimethyl-β-cyclodextrin as thermosensitive retardant for the radical polymerization of N-methacryloyl-L-tyrosine derivatives in water
Authors: Tabatabai Monir , Ritter Helmut , Schmelzer Monika 
Published: August 2014

AbstractThe synthesis and characterization of N-methacryloyl-L-tyrosine methyl ester (3a) and ethyl ester (3b), and their acetyl derivatives O-acetyl-N-methacryloyl- L-tyrosine methyl ester (4a) and ethyl ester (4b) are described. Monomers 3 and 4 were complexed with RAMEB (randomly methylated ß-cyclodextrin) yielding water soluble host-guest complexes 5a-d. The radical polymerization of monomers 3 and 4 was investigated in the presence as well as in the absence of RAMEB in aqueous medium at room temperature and also at 60°C. It is shown that the polymerization tendency of complexes 5a-d at room temperature is lower, leading to polymers of higher molecular weight, compared to the free monomers 3 and 4. Furthermore, the polymerization of monomers 3 and 4 was carried out in homogenous organic solution using 2,2’-azoisobutyronitrile as initiator, and the results are discussed.
Covalent immobilization of urease on polypyrrole microspheres for application as a urea biosensor
Authors: Gambhir Anamika , Kumar Arun , Malhotra Bansi D. , Miksa Beata , Slomkowski Stanislaw 
Published: August 2014

AbstractUrease has been covalently immobilized on polypyrrole microspheres chemically linked to conducting polypyrrole-polyvinyl sulfonate (PPY-PVS) films. These films were electrochemically prepared during 5 - 7 min at a constant current of 2 mA using indium - tin oxide (ITO) glass plates as the working electrode, and a standard calomel electrode as the reference electrode. Urease covalently linked to polypyrrole microspheres (by reaction of protein amino groups with aldehyde groups on the surface of the microspheres) was entrapped/adsorbed onto electrochemically prepared conducting PPY-PVS films deposited on ITO. Potentiometric measurements undertaken on these conducting polymer electrodes using an ammonium ion analyzer reveal that they can be used for estimating the urea concentration in solutions from 5·10-3 mol/l to 6·10-2 mol/l.
Biomedical applications of polymers 2001 - 2002
Authors: Jagur-Grodzinski Joseph 
Published: August 2014

Abstract Papers published during 2001 - 2002 on the synthesis and preparation of polymers and polymer-based devices and their applications are reviewed. Polymers for drug and gene delivery, gene therapy, controlled drug release, conjugation with peptides, proteins, and nucleotides, tissue engineering, bone repair and regeneration, coatings, wound dressing, artificial skin and other artificial organs are discussed.
The AA* + B*B2 approach A simple and convenient synthetic strategy towards hyperbranched polyurea-urethanes
Authors: Bruchmann Bernd , Schrepp Wolfgang 
Published: August 2014

Abstract Synthesizing hyperbranched polyurethanes in a one step process using commercially available raw materials: these were the primary conditions for this work. By taking advantage of intramolecular reactivity differences of isocyanate groups in diisocyanates in combination with reactivity differences of OH and NH groups in alkanolamines, it is possible to generate in situ AB2 molecules by controlling reactions of specific functional groups towards each other. This AA* + B*B2 approach works without protecting groups and opens up a simple and versatile strategy towards hyperbranched aromatic as well as aliphatic polyureaurethanes. Preferential diisocyanates for this synthesis were 2,4-toluylene diisocyanate and isophorone diisocyanate, whereas diethanolamine and diisopropanolamine were used as isocyanate-reactive counterparts.
Novel soluble blue emitting PPV-like polymers: synthesis and characterization
Authors: Gruber Jonas , Li Rosamaria W. C. , Ponce Patricia , Benvenho Adriano R. V. , Mello Regina M. Q. , Hümmelgen Ivo A. 
Published: August 2014

Abstract We report on the electrochemical synthesis of two novel soluble PPV-like polymers, poly(2-decyloxy-4,4'-biphenylenevinylene), DOPBV, and poly(2-decylsulfonyl- 4,4'-biphenylenevinylene), DSPBV, their spectroscopic and thermal characterization as well as their electrical properties. We also report on the use of sandwich devices Au/DOPBV/Al and Ni/DSPBV/Al to investigate the charge injection and transport characteristics, besides other important parameters such as the optical energy gap and the HOMO energy level, leading to an estimate of the ionization potential and electron affinity of these polymers.
On the entanglement density of differently N-substituted alternating styrene-maleimide copolymers
Authors: Teerenstra Marcel N. , Steeman Paul A. M. , Iwens Werner , Vandervelden Alexander , Suwier Davy R. , Van Mele Bruno , Koning Cor E. 
Published: August 2014

Abstract Differently N-substituted maleimides were copolymerized with styrene to yield alternating styrene-maleimide copolymers (SMI-R) with different chain diameters. The polymers were obtained by free radical polymerization and characterized by NMR and size exclusion chromatography / differential viscometry. Glass transition temperatures were measured by differential scanning calorimetry. An increase in chain diameter and chain stiffness is accompanied by a decrease in the entanglement density, reflected in lower values of the plateau modulus, which were corrected for the low molecular weight portion using the Wasserman/Graessley model. Increasing the chain diameter by a factor of two results in a decrease of the entanglement density to one third. SMI-Me showed a much lower entanglement density than polystyrene (PS) although they have the same chain diameter. SMIMe however is more rigid than PS because of the maleimide five-membered ring structure in the main chain. SMI-Me and SMI-PhOPh show the same glass transition temperature. However, because of the larger chain diameter of SMIPhOPh, it has a much lower entanglement density. Thus, both the chain flexibility and the chain diameter, two parameters that are strongly related, affect the entanglement density.
Determination of acid and hydroxyl end-groups in endfunctionalized polystyrenes using 19F NMR
Authors: Rajan Merina , Cotiuga Irina , Ma Yunqian , Picchioni Francesco , Agarwal Uday S. 
Published: August 2014

Abstract Carboxyl-terminated polystyrene was esterified with 2,2,2-trifluoroethanol using a carbodiimide-mediated room temperature reaction, and hydroxyl-terminated polystyrene was fluoro-derivatized with trifluoroacetic anhydride. The soformed fluorine-containing esters were then quantitatively determined with 19F NMR, using α,α,α-trifluorotoluene as secondary standard. This provides a technique for the reliable determination of carboxylic acid and hydroxyl groups in small samples of polymers.
In situ compatibilization of a polyetherimide and a thermotropic polyester using an epoxy resin
Authors: Turturro Antonio , Castellano Maila , Panzardi Gianluca , Valenti Barbara , Russo Saverio , Costa Giovanna , Falqui Luciano 
Published: August 2014

Abstract This study examines the compatibilization of the polyetherimide Ultem 1000 with the thermotropic liquid crystalline polymer Vectra A 950 by using an epoxy resin (PKFE) as compatibilizer. IR spectroscopy and electron-microscopic morphological analysis indicate the grafting of PKFE molecules on fibrillar domains of Vectra during melt mixing. Moreover, morphological analysis shows that the addition of PKFE improves the dispersion and decreases the size of Vectra fibrils. Both Vectra and PKFE significantly reduce the glass transition temperature of Ultem in ternary blends. The tensile modulus and the ultimate strength of the blends are improved with respect to those of neat Ultem. However, the final materials are very fragile. The roles of Vectra and PKFE are discussed.
Memory effect in melting behaviour, crystallization kinetics and morphology of poly(propylene terephthalate)
Authors: Sisti Laura , Finelli Lara , Lotti Nadia , Berti Corrado , Munari Andrea 
Published: August 2014

AbstractCrystallization kinetics and melting behaviour of poly(propylene terephthalate) (PPT) were investigated by means of differential scanning calorimetry and hot-stage optical microscopy. Isothermal crystallization kinetics was analysed according to the Avrami treatment. The effects of temperature and duration of melting on the overall rate of isothermal crystallization were studied: the rate was found to decrease with increasing melting temperature and melting time. This result was discussed on the basis of the gradual destruction of predetermined athermal nuclei. Values of the Avrami exponent close to 3 were obtained, regardless of the adopted thermal treatment and the crystallization temperature, Tc, in agreement with a crystallization process originating from predetermined nuclei and characterized by three-dimensional spherulitic growth. As a matter of fact, spacefilling spherulites were observed by optical microscopy at all Tc’s, independent of the applied thermal treatments. For each of them, the rate of crystallization became lower as Tc increased, as usual at low undercooling where the crystallization process is controlled by nucleation. The observed multiple endotherms, which are commonly displayed by polyesters, were influenced by Tc and ascribed to melting and recrystallization processes. Linear and non-linear treatments were applied in order to estimate the equilibrium melting temperature for PPT, by using the corrected melting temperatures. The non-linear estimation yielded an about 33°C higher value with respect to the one obtained by means of the linear approach. Through the analysis of secondary nucleation theory, the classical II→III transition was found to occur at a temperature of 194°C. The average work of chain folding for nucleation was determined to be c. 5.2 kcal/mol. The heat of fusion was correlated to the specific heat increment for samples with different degree of crystallinity and the results were interpreted on the basis of the existence of an interphase, whose amount was found to depend on the thermal treatment the polymer was subjected to.
Two-dimensional chromatography of complex polymers, 5 Separation of blends of styrene-butadiene rubber and butyl rubber
Authors: Heinz Lars-Christian , Siewing Anja , Pasch Harald 
Published: August 2014

Abstract Separation of blends of styrene-butadiene rubber and butyl rubber was accomplished by gradient HPLC. Using a polar stationary phase and chloroformcyclohexane as eluent, the blends were separated with regard to chemical composition, irrespective of the molar masses of the components. The exact chemical structure of the blend components was analysed by coupling the chromatographic separation to FTIR detection. FTIR spectra of the components reveal information on styrene and butadiene contents and the conformation of the butadiene units (1,2-, 1,4-cis and 1,4-trans units). Complete separation of the blends with respect to chemical composition and molar mass was achieved by two-dimensional liquid chromatography. Combining gradient HPLC and size exclusion chromatography in a fully automated 2D chromatography set-up, the complex distributions of chemical composition and molar mass were fingerprinted simultaneously.
Degradation of unstabilised polypropylene and a propene- 1-pentene copolymer
Authors: de Goede Stefan , Brüll Robert , Pasch Harald , Marshall Niall 
Published: August 2014

Abstract The degradation of polypropylene (PP) and a propene-1-pentene copolymer (P2) have been monitored with regard to chemical composition, molar mass distribution and chemical composition distribution. The increase in the carbonyl index can be monitored by IR and a decrease in molar mass can be observed from size-exclusion chromatography (SEC). CRYSTAF shows that the chemical heterogeneity of the samples broadens with continuing degradation. SEC-FTIR reveals that the degraded species are mainly found in the low-molecular-weight end of the molar mass distribution. Spatial heterogeneity of the degradation process has been proven by the analysis of abrased layers. It was found that the P2 copolymer degrades at a higher rate compared to PP.
Solvation of poly(methyl acrylate) and poly(vinyl acetate) by CO2 studied via atomistic Monte Carlo simulation techniques
Authors: Beuermann Sabine , Buback Michael , Drache Marco , Nelke Dorit , Schmidt-Naake Gudrun 
Published: August 2014

Abstract The differences in solubility of poly(vinyl acetate) (PVAc) and poly(methyl acrylate) (PMA) were addressed by applying atomistic Monte Carlo simulation techniques. Polymer segments consisting of nine monomer units serve as model compounds for polymer chains. As a measure of intermolecular interactions with the solvent environment, cohesion energies of the polymer segments embedded in either the corresponding monomer or in CO2 were calculated. Only in case of PMA segments in CO2 environment, specific interactions between polymer segments were identified. This finding is in agreement with experimental results on phase behaviour and propagation kinetics.