bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polypropylene–clay nanocomposites: Influence of low molecular weight polar additives on intercalation and exfoliation behavior
Authors: Ratnayake U.N. , Haworth B. 
Published: June 2006

AbstractThe influence of low molecular weight additives containing polar groups and modified polyolefin‐based compatibilizers on polypropylene (PP)‐clay nanocomposites (PPCN) has been studied, in terms of intercalation and degree of exfoliation achievable by melt‐state mixing processes. PPCN were prepared by melt mixing two PP homopolymers with organically‐modified montmorillonite type clay, in the presence of maleic anhydride‐grafted polypropylene (PP‐MA) compatibilizer. XRD analysis shows that interlayer spacing of clay has been increased dramatically, while TEM results show a significant improvement of clay dispersion in the PP matrix, when nanocomposites are prepared with commercial PP containing short‐chain organic additives with polar end groups. Subsequent studies based upon customized PP formulations, with amide‐type slip additive, confirm the intercalation of this additive into the clay galleries and its positive and significant impact on clay dispersion. Contact angle measurements suggest that these additives diffuse into the clay gallery space rather than migrating away from the bulk of the PPCN matrix. The interaction between polar group (NH2) of this additive and the polar sites on the filler surface appears to be the driving force for the intercalation. POLYM. ENG. SCI. 46:1008–1015, 2006. © 2006 Society of Plastics Engineers
Characterization and mechanical properties of poly(lactic acid)/poly(ϵ‐caprolactone)/organoclay nanocomposites prepared by melt compounding
Authors: Hasook Aniwat , Tanoue Shuichi , Iemoto Yoshiyuki , Unryu Tsunemune 
Published: June 2006

AbstractThis study investigates the preparation, characterization, and mechanical properties of nanocomposites prepared from poly(lactic acid) (PLA), an organoclay, hereafter referred to as Clay, and poly(ε‐caprolactone) (PCL) by melt compounding in a co‐rotating type, twin screw extruder. The molecular weight of the PCL used was 10K, 40K, or 70–100K. Tensile test data show that the Young's modulus of the PLA/Clay nanocomposite was about 19% higher than that of neat PLA. The tensile strength of the PLA/PCL(10K and 40K)/Clay nanocomposites was about 17% higher than that of neat PLA. On the other hand, the tensile strength of the PLA/PCL(70–100K)/Clay sample was about 7% lower than that of neat PLA. The elongation of the PLA/PCL/Clay composite also improved. The effect of d‐spacing, resulting from adding PCL to the PLA/Clay nanocomposite, depends on the molecular weight of the PCL. The size of the clay agglomerates in the PLA/PCL/Clay nanocomposites is larger than those found in the PLA/Clay. Furthermore, the thermal stability of the PLA/Clay nanocomposite increases with the addition of PCL. On the whole, PCL(10K) was found to be the best additive for PLA/Clay nanocomposites. POLYM. ENG. SCI. 46:1001–1007, 2006. © 2006 Society of Plastics Engineers
Nanocrystalline dye‐sensitized solar cells having maximum performance
Authors: Kroon J. M. , Bakker N. J. , Smit H. J. P. , Liska P. , Thampi K. R. , Wang P. , Zakeeruddin S. M. , Grätzel M. , Hinsch A. , Hore S. , Würfel U. , Sastrawan R. , Durrant J. R. , Palomares E. , Pettersson H. , Gruszecki T. , Walter J. , Skupien K. , Tulloch G. E. 
Published: June 2006

AbstractThis paper presents an overview of the research carried out by a European consortium with the aim to develop and test new and improved ways to realise dye‐sensitized solar cells (DSC) with enhanced efficiencies and stabilities. Several new areas have been explored in the field of new concepts and materials, fabrication protocols for TiO2 and scatterlayers, metal oxide blocking layers, strategies for co‐sensitization and low temperature processes of platinum deposition. Fundamental understanding of the working principles has been gained by means of electrical and optical modelling and advanced characterization techniques. Cost analyses have been made to demonstrate the potential of DSC as a low cost thin film PV technology. The combined efforts have led to maximum non‐certified power conversion efficiencies under full sunlight of 11% for areas <0ċ2 cm2 and 10ċ1% for a cell with an active area of 1ċ3 cm2. Lifetime studies revealed negligible device degradation after 1000 hrs of accelerated tests under thermal stress at 80°C in the dark and visible light soaking at 60°C. An outlook summarizing future directions in the research and large‐scale production of DSC is presented. Copyright © 2006 John Wiley & Sons, Ltd.
Proteome analysis ofSchizosaccharomyces pombeby two‐dimensional gel electrophoresis and mass spectrometry
Authors: Hwang Kyung‐Hoon , Carapito Christine , Böhmer Susanne , Leize Emmanuelle , Van Dorsselaer Alain , Bernhardt Rita 
Published: June 2006

AbstractThe fission yeastSchizosaccharomyces pombe(S. pombe) is a unicellular eukaryote and contains many genes and regulatory mechanisms that are close to those of mammals. In this study, we performed a global proteomic analysis of the fission yeastS. pombewild type h−SL 972 proteome. More than 1500 protein spots were visualized on silver stained 2‐D gels in the 3–10 pIrange with a high resolution and high reproducibility. Protein identification was carried out by MALDI‐TOF‐MS and/or nanoLC‐MS/MS. Advantage of the complementarity of these two MS approaches was used to enhance the identification quality. So far, 364 proteins (representing 157 different proteins) have been identified. We report here the identification of 117 new proteins on our 2‐D reference map of this yeast compared to the first reference map. Of these identified proteins, 40.1% were involved in metabolism. The present work provides a very useful tool for all studies relying onS. pombeas a model organism and is a considerable complement to the first reference map ofS. pombepublished recently by Sun and coworkers (Sun, N., Jang, J., Lee, S., Kim, S. et al..,Proteomics2005,5, 1574–1579).
Recent progresses in the application of machine learning approach for predicting protein functional class independent of sequence similarity
Authors: Han Lianyi , Cui Juan , Lin Honghuang , Ji Zhiliang , Cao Zhiwei , Li Yixue , Chen Yuzong 
Published: June 2006

AbstractProtein sequence contains clues to its function. Functional prediction from sequence presents a challenge particularly for proteins that have low or no sequence similarity to proteins of known function. Recently, machine learning methods have been explored for predicting functional class of proteins from sequence‐derived properties independent of sequence similarity, which showed promising potential for low‐ and non‐homologous proteins. These methods can thus be explored as potential tools to complement alignment‐ and clustering‐based methods for predicting protein function. This article reviews the strategies, current progresses, and underlying difficulties in using machine learning methods for predicting the functional class of proteins. The relevant software and web‐servers are described. The reported prediction performances in the application of these methods are also presented, which need to be interpreted with caution as they are dependent on such factors as datasets used and choice of parameters.
Comparative proteome analysis of changes in the 26S proteasome during oocyte maturation in goldfish
Authors: Horiguchi Ryo , Dohra Hideo , Tokumoto Toshinobu 
Published: June 2006

AbstractProteasomes are large, multi‐subunit particles that act as the proteolytic machinery for most of the regulated intracellular protein degradation in eukaryotic cells. An alteration of proteasome function may be important for the regulation of the meiotic cell cycle. To study the change at the subunit level of the 26S proteasome during meiotic maturation, we purified 26S proteasomes from immature and mature oocytes of goldfish. Two‐dimensional polyacrylamide gel electrophoresis was used to separate proteins. For differential analysis, whole spots of the 26S proteasome from goldfish oocytes were identified by matrix‐assisted laser desorption/ionization‐time of flight mass spectrometry and database analysis. Four spots that were different (only detected in mature oocyte 265 proteasomes and not in immature ones) and four protein spots that were up‐ or down‐regulated were identified unambiguously. The mature‐specific spots were not 26S proteasome components but rather their interacting proteins, and were identified as chaperonin‐containing TCP‐1 subunits and myosin light chain. Minor spots of three subunits of the 20S core particle and one of the 19S regulatory particle showed meiotic cell cycle‐dependent changes. These results demonstrate that modifications of proteasomal subunits and cell cycle phase‐dependent interactions of proteins with proteasomes occur during oocyte maturation in goldfish.
Proteomic analysis of antigens from Leishmania infantum promastigotes
Authors: Dea‐Ayuela María Auxiliadora , Rama‐Iñiguez Sara , Bolás‐Fernández Francisco 
Published: June 2006

AbstractLeishmaniasis is a zoonotic disease caused by the species of the genus Leishmania, flagellated protozoa that multiply inside mammalian macrophages and are transmitted by the bite of the sandfly. The disease is widespread and due to the lack of fully effective treatment and vaccination the search for new drugs and immune targets is needed. Proteomics seems to be a suitable strategy because the annotated sequenced genome of L. major is available. Here, we present a high‐resolution proteome for L. infantum promastigotes comprising of around 700 spots. Western blot with rabbit hyperimmune serum raised against L. infantum promastiogote extracts and further analysis by MALDI‐TOF and MALDI‐TOF/TOF MS allowed the identification of various relevant functional antigenic proteins. Major antigenic proteins were identified as propionil carboxilasa, ATPase beta subunit, transketolase, proteasome subunit, succinyl‐diaminopimelate desuccinylase, a probable tubulin alpha chain, the full‐size heat shock protein 70, and several proteins of unknown function. In addition, one enzyme from the ergosterol biosynthesis pathway (adrenodoxin reductase) and the structural paraflagellar rod protein 3 (PAR3) were found among non‐antigenic proteins. This study corroborates the usefulness of proteomics in identifying new proteins with crucial biological functions in Leishmania parasites.
Reactivity trends and stereospecificity in nucleophilic substitution reactions
Authors: Uggerud Einar 
Published: June 2006

AbstractTo obtain the full overview of the mechanistic landscape of nucleophilic substitution reactions is a demanding pursuit. There are still many unexplored regions, and humility and carefulness should be exercised before drawing the final map. This review commentary emphasizes some recent findings of relevance to these questions. A critical account is given about commonly used concepts and practices for interpretation of reactivity trends. It is questioned whether the SN2/SN1 paradigm is fully appropriate for understanding the factors which govern the outcome of substitution reactions. Copyright © 2006 John Wiley & Sons, Ltd.
Synthesis and study of novel polyol‐bound photosensitizers for cationic UV‐curable systems
Authors: Chen Zhigang , Webster Dean C. 
Published: June 2006

AbstractNovel cationic intramolecular hydrogen abstraction photosensitizers (IHA‐PSs) based on a proposed intramolecular hydrogen abstraction photosensitization (IHAP) mechanism were synthesized and found to have a pronounced photosensitization effect in cycloaliphatic epoxide based cationic UV‐curable systems using sulfonium salt photoinitiators. A series of polyol‐based photosensitizers were synthesized with naphthalene attached. One photosensitizer, P‐Na, was found to have a more pronounced photosensitization effect in three different formulation systems, as revealed by real‐time Fourier transform infrared and differential photocalorimetry experiments. Such a phenomenon can be explained by a proposed facile IHAP mechanism, which is possible only with the unique molecular structure of P‐Na. The effect of P‐Na was further confirmed by comparison with two non‐polyol‐type photosensitizers. A designed IHA‐PS molecule was synthesized with the proposed principles ofthe IHAP mechanism, and it achieved a photosensitization effect similar to that of P‐Na with a much lower molecular weight and fewer hydroxyl groups per molecule. This further validated the proposed IHAP mechanism. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4435–4449, 2006
Influence of hexadecane on the formation of droplets and growth of particles for methyl methacrylate miniemulsion polymerization
Authors: Jeng Jauder , Dai Chi‐An , Chiu Wen‐Yen , Chern Chorng‐Shyan , Lin King‐Fu , Young Pin‐Yen 
Published: June 2006

AbstractThe evolution of monomer droplets and latex particles of methyl methacrylate miniemulsions, initiated by an oil‐phase initiator, stabilized by a cationic surfactant mixture, and costabilized by different amounts of hexadecane, was investigated. With an increasing hexadecane concentration, the ultrasonication time required for the miniemulsions to reach a critically stabilized state was reduced, and a unimodal size distribution of the droplets with a decreasing average diameter was obtained. For lower hexadecane concentrations, a bimodal size distribution of the latex particles, with a significant increase in the volume fraction of the smaller latex particles, was achieved after the polymerization. The enhanced growth of the volume fraction of the smaller latex particles came from both nucleation of the shrinking droplets due to Ostwald ripening and homogeneous and/or micellar nucleation, if micelles existed, triggered by radicals in the aqueous phase. For high hexadecane concentrations, Ostwald ripening was effectively retarded, and the miniemulsions were sufficiently stabilized against the degradation of molecular diffusion. The size distributions of the droplets and latex particles were almost identical. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4603–4610, 2006
Novel organosoluble polynorbornene bearing a polar, pendant, ester‐bridged epoxy group via living ring‐opening metathesis polymerization
Authors: Liaw Der‐Jang , Huang Ching‐Cheng , Fu Chun‐Wei 
Published: June 2006

AbstractA novel organosoluble polynorbornene bearing a polar, pendant, ester‐bridged epoxy group [poly(oxiran‐2‐ylmethyl 2‐methylbicyclo[2.2.1]hept‐5‐ene‐2‐carboxylate) (polyOMMC)] was prepared via the living ring‐opening metathesis polymerization (ROMP) of active norbornenes with a Ru catalyst. PolyOMMC exhibited excellent solubility in a variety of solvents. The number‐average molecular weight of polyOMMC linearly increased with the [M]/[I] ratio (where [M] is the monomer concentration and [I] is the initiator concentration), and a narrow polydispersity of 1.09–1.19 was observed; this was considered a living polymerization. When ROMP of oxiran‐2‐ylmethyl 2‐methylbicyclo[2.2.1]hept‐5‐ene‐2‐carboxylate with [M]/[I] = 350 was carried out at 30 °C in CH2Cl2, the number‐average molecular weight (7.01 × 104; polydispersity index = 1.07) was close to the calculated molecular weight (7.28 × 104), and a diblock copolymer was observed after the addition of another monomer ([M]/[I] = 350) with an increase in the number‐average molecular weight (1.60 × 105; polydispersity index = 1.11), which was close to the calculated molecular weight (1.61 × 105). The modified polynorbornenes retained good solubility in methylene chloride, tetrahydrofuran, dimethyl sulfoxide, dimethylformamide, N,N‐dimethylacetamide, and N‐methyl‐2‐pyrrdione. High‐performance polynorbornenes with active epoxy groups could be designed with great potential for applications in photoresists, UV curing, and elastomers. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4428–4434, 2006
Poly(p‐phenylene vinylene) derivatives containing triazole or oxadiazole segments: Connector effect in optical, electrochemical, and electroluminescent properties
Authors: Chen Shinn‐Horng , Chen Yun 
Published: June 2006

AbstractTo study the effect of connector structure between hole‐ and electron‐transporting segments, we synthesized and characterized new electroluminescent polymers P1–P7 consisting of hole‐transporting 1,4‐bis(hexyloxy)‐2,5‐distyrylbenzene (DSB: P1 and P2) and electron‐transporting 4‐(4‐(hexyloxy)phenyl)‐3,5‐diphenyl‐4H‐1,2,4‐triazole (TAZ: P3 and P4) or 2‐(2,5‐bis(hexyloxy)‐4‐(5‐phenyl‐1,3,4‐oxadiazol)phenyl)‐5‐phenyl‐1,3,4‐oxadiazole (DIOXD: P5–P7) segments linked by different connectors. The connectors between hole‐ and electron‐transporting segments are (1) 1,4‐phenylene in P3 and P5, (2) 1,4‐divinylbenzene in P4 and P6, and (3) 4,4′‐biphenyl in P7. Three corresponding end‐capped model polymers P1‐M, P2‐M, and P3‐M were also synthesized to evaluate the effect of end groups. From optimized semiempirical MNDO calculations, the adjacent benzene rings between DSB and TAZ or DIOXD chromophores in P3, P5, and P7 twist about 81°–89°. The effect of twisted architectures and connectors in optical and electrochemical properties for P1–P7 have been discussed by comparing with copolymers P1 and P2, which possess single bond or ether spacer as connectors. From cyclic voltammograms, the torsion in P3, P5, and P7 confines electron delocalization and leads to simultaneously enhanced hole and electron affinity as compared to those of P1 and P2. Furthermore, double‐layer light‐emitting diodes with a configuration of ITO/PEDOT:PSS/P1–P7/Al all reveal green–yellow electroluminescence with maximum luminance at 8–320 cd/m2 and their performances are greatly influenced by the connector's structure. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4514–4531, 2006
Poly(fluorenevinylene) derivatives by Heck coupling: Synthesis, photophysics, and electroluminescence
Authors: Mikroyannidis John A. , Yu Young‐jun , Lee Seung‐hun , Jin Jung‐il 
Published: June 2006

AbstractThree new poly(fluorenevinylene) derivatives were synthesized, characterized, and used as emissive materials in light‐emitting diodes (LEDs). They were synthesized by Heck coupling of 9,9‐dihexyl‐2,7‐divinylfluorene with 2,7‐dibromo‐9,9‐dihexylfluorene, 2,3‐bis(4‐bromophenyl)quinoxaline, or 2,5‐bis(4‐bromophenyl)‐3,4‐diphenylthiophene to afford the polymers F, Q, and T, respectively. Polymers F and Q had medium number–average molecular weights (Mn ˜ 14,000) with relatively narrow polydispersity (1.3–1.6), while T was obtained as an oligomer (Mn ˜ 4000). All polymers were soluble in common organic solvents, such as tetrahydrofuran (THF), chloroform, dichloromethane, and toluene. They emitted blue‐greenish fluorescence light in dilute THF solution (444–491 nm), with photoluminescence (PL) quantum yields of 0.32–0.54, and in thin film (453–488 nm). LEDs with the configuration of ITO/PEDOT‐PSS/Polymer/Li:Al were fabricated and evaluated. The electroluminescence (EL) spectra of the Q and F polymers were very broad covering the blue–green–red region, whereas the spectrum of the polymer T was almost purely blue. The threshold electrical field for light emission of the devices was almost the same (˜1.75 MV/cm). The external quantum efficiency of the devices of polymers Q and F was about 1.0 × 10−3%, whereas that of polymer T was ˜3.0 × 10−5%. The fluorescence lifetime of polymers F and Q was significantly longer than that of the polymer T. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4494–4507, 2006
Polyampholyte terpolymers of amphoteric, amino acid‐based monomers with acrylamide and (3‐acrylamidopropyl)trimethyl ammonium chloride
Authors: Ezell Ryan G. , Gorman Irene , Lokitz Brad , Treat Neil , Mcconaughy Shawn D. , Mccormick Charles L. 
Published: June 2006

AbstractLow‐charge‐density amphoteric copolymers and terpolymers composed of acrylamide, (3‐acrylamidopropyl)trimethyl ammonium chloride, and the amino acid derived monomers (e.g., N‐acryloyl valine, N‐acryloyl alanine, and N‐acryloyl aspartate) were prepared via free‐radical polymerization in aqueous media to yield terpolymers with random charge distributions and homogeneous compositions. Sodium formate (NaOOCH) was employed as a chain transfer agent during the polymerization to suppress gel effects and broadening of the molecular weight distribution. Terpolymer compositions were determined by 13C and 1H NMR spectroscopy. Terpolymer molecular weights and polydispersity indices were obtained via size exclusion chromatography/multi‐angle laser light scattering, and hydrodynamic diameter values were obtained via dynamic light scattering. The solution properties of low‐charge‐density amphoteric copolymers and terpolymers have been studied as a function of solution pH, ionic strength, and polymer concentration. The low‐charge‐density terpolymers display excellent solubility in deionized (DI) water with no phase separation. The charge‐balanced terpolymers exhibit antipolyelectrolyte behavior at pH values ≥(6.5 ± 0.2). As solution pH is decreased, these charge‐balanced terpolymers become increasingly cationic because of the protonation of the anionic repeat units. Charge‐imbalanced terpolymers generally demonstrate polyelectrolyte behavior, although the effects of intramolecular electrostatic interactions (e.g., polyampholyte effects) on the hydrodynamic volume are evident at certain values of solution pH and salt concentration. The aqueous solution behavior (i.e., globule‐to‐coil transition at the isoelectric point in the presence of salt and globule elongation with increasing charge asymmetry) of the terpolymers in the dilute regime correlates well with that predicted by the polyampholyte solution theories of Dobrynin and Rubinstein as well as Kantor and Kardar. Examination of comonomer charge density, hydrogen‐bonding ability, and spacer group (e.g., the moiety separating the ionic group from the polymer chain) indicates that conformational restrictions of the amino acid comonomers result in increased chain stiffness and higher solution viscosities in DI water and brine solutions. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4479–4493, 2006
Homopolymerization of cyclic esters initiated by lanthanide isopropoxides supported by 2,2′‐ethylene‐bis(4,6‐di‐tert‐butylphenolate) ligands
Authors: Xu Xiaoping , Yao Yingming , Hu Mingyu , Zhang Yong , Shen Qi 
Published: June 2006

AbstractLanthanide isopropoxides supported by carbon‐bridged bisphenolate ligands of 2,2′‐ethylene‐bis(4,6‐di‐tert‐butylphenoxo) {[(EDBP)Ln(μ‐OPri)(THF)2]2, where Ln is Nd (1), Sm (2), or Yb (3) and THF is tetrahydrofuran} were synthesized by protic exchange reactions in high yields with Cp3Ln compounds as raw materials, and complex 1 was structurally characterized. Complexes 1–3 were shown to be efficient initiators for the ring‐opening polymerization of ε‐caprolactone (ε‐CL) and 2,2‐dimethyltrimethylene carbonate (DTC). Complexes 1–3 could initiate the controlled polymerization of ε‐CL, and the polymerization rate was first‐order with respect to the monomer. The influence of the reaction conditions on the monomer conversion, molecular weight, and molecular weight distribution of the resultant polymers was investigated. End‐group analyses of the oligomers of ε‐CL and DTC showed that the polymerization underwent a coordination–insertion mechanism. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4409–4419, 2006